2021 |
Keys, P H; Steiner, O; Vigeesh, G On the effect of oscillatory phenomena on Stokes inversion results Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200182, 2021. @article{2021RSPTA.37900182K, title = {On the effect of oscillatory phenomena on Stokes inversion results}, author = {P H {Keys} and O {Steiner} and G {Vigeesh}}, url = {https://arxiv.org/abs/2008.05539}, doi = {10.1098/rsta.2020.0182}, year = {2021}, date = {2021-02-01}, journal = {Philosophical Transactions of the Royal Society of London Series A}, volume = {379}, number = {2190}, pages = {20200182}, abstract = {Stokes inversion codes are crucial in returning properties of the solar atmosphere, such as temperature and magnetic field strength. However, the success of such algorithms to return reliable values can be hindered by the presence of oscillatory phenomena within magnetic wave guides. Returning accurate parameters is crucial to both magnetohydrodynamics (MHD) studies and solar physics in general. Here, we employ a simulation featuring propagating MHD waves within a flux tube with a known driver and atmospheric parameters. We invert the Stokes profiles for the 6301 Å and 6302 Å line pair emergent from the simulations using the well-known Stokes Inversions from Response functions code to see if the atmospheric parameters can be returned for typical spatial resolutions at ground-based observatories. The inversions return synthetic spectra comparable to the original input spectra, even with asymmetries introduced in the spectra from wave propagation in the atmosphere. The output models from the inversions match closely to the simulations in temperature, line-of-sight magnetic field and line-of-sight velocity within typical formation heights of the inverted lines. Deviations from the simulations are seen away from these height regions. The inversions results are less accurate during passage of the waves within the line formation region. The original wave period could be recovered from the atmosphere output by the inversions, with empirical mode decomposition performing better than the wavelet approach in this task. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Stokes inversion codes are crucial in returning properties of the solar atmosphere, such as temperature and magnetic field strength. However, the success of such algorithms to return reliable values can be hindered by the presence of oscillatory phenomena within magnetic wave guides. Returning accurate parameters is crucial to both magnetohydrodynamics (MHD) studies and solar physics in general. Here, we employ a simulation featuring propagating MHD waves within a flux tube with a known driver and atmospheric parameters. We invert the Stokes profiles for the 6301 Å and 6302 Å line pair emergent from the simulations using the well-known Stokes Inversions from Response functions code to see if the atmospheric parameters can be returned for typical spatial resolutions at ground-based observatories. The inversions return synthetic spectra comparable to the original input spectra, even with asymmetries introduced in the spectra from wave propagation in the atmosphere. The output models from the inversions match closely to the simulations in temperature, line-of-sight magnetic field and line-of-sight velocity within typical formation heights of the inverted lines. Deviations from the simulations are seen away from these height regions. The inversions results are less accurate during passage of the waves within the line formation region. The original wave period could be recovered from the atmosphere output by the inversions, with empirical mode decomposition performing better than the wavelet approach in this task. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'. |
Fleck, B; Carlsson, M; Khomenko, E; Rempel, M; Steiner, O; Vigeesh, G Acoustic-gravity wave propagation characteristics in three-dimensional radiation hydrodynamic simulations of the solar atmosphere Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200170, 2021. @article{2021RSPTA.37900170F, title = {Acoustic-gravity wave propagation characteristics in three-dimensional radiation hydrodynamic simulations of the solar atmosphere}, author = {B {Fleck} and M {Carlsson} and E {Khomenko} and M {Rempel} and O {Steiner} and G {Vigeesh}}, url = {https://arxiv.org/abs/2007.05847}, doi = {10.1098/rsta.2020.0170}, year = {2021}, date = {2021-02-01}, journal = {Philosophical Transactions of the Royal Society of London Series A}, volume = {379}, number = {2190}, pages = {20200170}, abstract = {There has been tremendous progress in the degree of realism of three- dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two orders of magnitude between the models, and the phase difference spectra of several models show unexpected features, including ensuremathpm180textdegree phase jumps. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There has been tremendous progress in the degree of realism of three- dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two orders of magnitude between the models, and the phase difference spectra of several models show unexpected features, including ensuremathpm180textdegree phase jumps. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'. |
Vigeesh, G; Roth, M; Steiner, O; Fleck, B On the influence of magnetic topology on the propagation of internal gravity waves in the solar atmosphere Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200177, 2021. @article{2021RSPTA.37900177V, title = {On the influence of magnetic topology on the propagation of internal gravity waves in the solar atmosphere}, author = {G {Vigeesh} and M {Roth} and O {Steiner} and B {Fleck}}, url = {https://arxiv.org/abs/2010.06926}, doi = {10.1098/rsta.2020.0177}, year = {2021}, date = {2021-02-01}, journal = {Philosophical Transactions of the Royal Society of London Series A}, volume = {379}, number = {2190}, pages = {20200177}, abstract = {The solar surface is a continuous source of internal gravity waves (IGWs). IGWs are believed to supply the bulk of the wave energy for the lower solar atmosphere, but their existence and role for the energy balance of the upper layers is still unclear, largely due to the lack of knowledge about the influence of the Sun's magnetic fields on their propagation. In this work, we look at naturally excited IGWs in realistic models of the solar atmosphere and study the effect of different magnetic field topographies on their propagation. We carry out radiation- magnetohydrodynamic simulations of a magnetic field free and two magnetic models-one with an initial, homogeneous, vertical field of 100 G magnetic flux density and one with an initial horizontal field of 100 G flux density. The propagation properties of IGWs are studied by examining the phase-difference and coherence spectra in the k$_ħ$ - ensuremathømega diagnostic diagram. We find that IGWs in the upper solar atmosphere show upward propagation in the model with predominantly horizontal field similar to the model without magnetic field. In contrast to that the model with predominantly vertical fields show downward propagation. This crucial difference in the propagation direction is also revealed in the difference in energy transported by waves for heights below 0.8 Mm. Higher up, the propagation properties show a peculiar behaviour, which require further study. Our analysis suggests that IGWs may play a significant role in the heating of the chromospheric layers of the internetwork region where horizontal fields are thought to be prevalent. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The solar surface is a continuous source of internal gravity waves (IGWs). IGWs are believed to supply the bulk of the wave energy for the lower solar atmosphere, but their existence and role for the energy balance of the upper layers is still unclear, largely due to the lack of knowledge about the influence of the Sun's magnetic fields on their propagation. In this work, we look at naturally excited IGWs in realistic models of the solar atmosphere and study the effect of different magnetic field topographies on their propagation. We carry out radiation- magnetohydrodynamic simulations of a magnetic field free and two magnetic models-one with an initial, homogeneous, vertical field of 100 G magnetic flux density and one with an initial horizontal field of 100 G flux density. The propagation properties of IGWs are studied by examining the phase-difference and coherence spectra in the k$_ħ$ - ensuremathømega diagnostic diagram. We find that IGWs in the upper solar atmosphere show upward propagation in the model with predominantly horizontal field similar to the model without magnetic field. In contrast to that the model with predominantly vertical fields show downward propagation. This crucial difference in the propagation direction is also revealed in the difference in energy transported by waves for heights below 0.8 Mm. Higher up, the propagation properties show a peculiar behaviour, which require further study. Our analysis suggests that IGWs may play a significant role in the heating of the chromospheric layers of the internetwork region where horizontal fields are thought to be prevalent. textbackslashtextbackslashThis article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'. |
2019 |
K. Upadhyay B. Joshi, Mitra Bhattacharyya Oberoi P K R D; Monstein, C Solar Radio Observation Using CALLISTO at the USO/PRL, Udaipur Inproceedings In: 2019 IEEE MTT-S International Microwave and RF Conference (IMARC), pp. 1-6, 2019. @inproceedings{9118669, title = {Solar Radio Observation Using CALLISTO at the USO/PRL, Udaipur}, author = {K. Upadhyay, B. Joshi, P. K. Mitra, R. Bhattacharyya, D. Oberoi and C. Monstein}, url = {http://arxiv.org/abs/2007.01655}, doi = {10.1109/IMaRC45935.2019.9118669}, year = {2019}, date = {2019-12-01}, booktitle = {2019 IEEE MTT-S International Microwave and RF Conference (IMARC)}, pages = {1-6}, abstract = {This paper presents a detailed description of various subsystems of CALLISTO solar radio spectrograph installed at the USO/PRL. In the front-end system, a log periodic dipole antenna (LPDA) is designed for the frequency range of 40-900 MHz. In this paper LPDA design, its modifications, and simulation results are presented. We also present some initial observations taken by CALLISTO at Udaipur.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } This paper presents a detailed description of various subsystems of CALLISTO solar radio spectrograph installed at the USO/PRL. In the front-end system, a log periodic dipole antenna (LPDA) is designed for the frequency range of 40-900 MHz. In this paper LPDA design, its modifications, and simulation results are presented. We also present some initial observations taken by CALLISTO at Udaipur. |
Sampoorna, M; Nagendra, K N; Sowmya, K; Stenflo, J O; Anusha, L S Polarized Line Formation with Incomplete Paschen-Back Effect and Partial Frequency Redistribution Inproceedings In: Werner, K; Stehle, C; Rauch, T; Lanz, T (Ed.): Astronomical Society of the Pacific Conference Series, pp. 113, 2019. @inproceedings{2019ASPC..519..113S, title = {Polarized Line Formation with Incomplete Paschen-Back Effect and Partial Frequency Redistribution}, author = {M. {Sampoorna} and K.N. {Nagendra} and K. {Sowmya} and J.O. {Stenflo} and L.S. {Anusha}}, editor = {K {Werner} and C {Stehle} and T {Rauch} and T {Lanz}}, year = {2019}, date = {2019-07-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {519}, pages = {113}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {Quantum interference between the hyperfine structure states is known to depolarize the cores of some of the lines in the linearly polarized spectrum of the Sun (the Second Solar Spectrum). The presence of external magnetic fields in the line forming regions modify these signatures through the Hanle, Zeeman, and incomplete/ complete Paschen-Back effects (PBE), depending on the strength of the magnetic field. In an earlier paper, Sowmya et al. (2014) derived the relevant collisionless partial frequency redistribution (PFR) matrix for scattering on a two- level atom with hyperfine structure splitting (HFS) and in the presence of arbitrary strength magnetic fields (including the PBE regime). In the present paper we solve the problem of polarized line transfer in a magnetized atmosphere, including this PFR matrix. For this purpose, we apply a scattering expansion method which is based on orders of scattering approach. We present the results on the combined effects of PBE and PFR on the polarized line profiles using the atomic parameters relevant to the Na I D$_2$ line.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Quantum interference between the hyperfine structure states is known to depolarize the cores of some of the lines in the linearly polarized spectrum of the Sun (the Second Solar Spectrum). The presence of external magnetic fields in the line forming regions modify these signatures through the Hanle, Zeeman, and incomplete/ complete Paschen-Back effects (PBE), depending on the strength of the magnetic field. In an earlier paper, Sowmya et al. (2014) derived the relevant collisionless partial frequency redistribution (PFR) matrix for scattering on a two- level atom with hyperfine structure splitting (HFS) and in the presence of arbitrary strength magnetic fields (including the PBE regime). In the present paper we solve the problem of polarized line transfer in a magnetized atmosphere, including this PFR matrix. For this purpose, we apply a scattering expansion method which is based on orders of scattering approach. We present the results on the combined effects of PBE and PFR on the polarized line profiles using the atomic parameters relevant to the Na I D$_2$ line. |
Sampoorna, M; Nagendra, K N; Frisch, H; Stenflo, J O Effects of Angle-Dependent Partial Frequency Redistribution on Polarized Line Profiles Inproceedings In: Werner, K; Stehle, C; Rauch, T; Lanz, T (Ed.): Astronomical Society of the Pacific Conference Series, pp. 109, 2019. @inproceedings{2019ASPC..519..109S, title = {Effects of Angle-Dependent Partial Frequency Redistribution on Polarized Line Profiles}, author = {M. {Sampoorna} and K.N. {Nagendra} and H. {Frisch} and J.O. {Stenflo}}, editor = {K {Werner} and C {Stehle} and T {Rauch} and T {Lanz}}, year = {2019}, date = {2019-07-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {519}, pages = {109}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {Scattering of the solar limb-darkened radiation field on atoms and molecules produces linearly polarized spectrum of the Sun (Second Solar Spectrum). Partial frequency redistribution (PFR) plays a fundamental role in shaping the wings of linearly polarized profiles of strong resonance lines. Here we present the effects of the angle-dependent (AD) PFR on resonance polarization both in the presence and absence of magnetic fields. We consider scattering on a two-level atom with unpolarized lower level, and a one-dimensional isothermal atmosphere.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Scattering of the solar limb-darkened radiation field on atoms and molecules produces linearly polarized spectrum of the Sun (Second Solar Spectrum). Partial frequency redistribution (PFR) plays a fundamental role in shaping the wings of linearly polarized profiles of strong resonance lines. Here we present the effects of the angle-dependent (AD) PFR on resonance polarization both in the presence and absence of magnetic fields. We consider scattering on a two-level atom with unpolarized lower level, and a one-dimensional isothermal atmosphere. |
Ramelli, R; Bianda, M; Berdyugina, S; Belluzzi, L; Kleint, L Measurement of the Evolution of the Magnetic Field of the Quiet Photosphere over a Solar Cycle Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 283, 2019. @inproceedings{2019ASPC..526..283R, title = {Measurement of the Evolution of the Magnetic Field of the Quiet Photosphere over a Solar Cycle}, author = {R {Ramelli} and M {Bianda} and S {Berdyugina} and L {Belluzzi} and L {Kleint}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0283.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {283}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The solar photosphere is filled by magnetic fields tangled at scales much smaller than the resolution capability of solar telescopes. These hidden magnetic fields can be investigated via the Hanle effect. In 2007, we started a synoptic program to explore whether the magnetic flux of the quiet photosphere varies with the solar cycle. For this purpose we applied a differential Hanle effect technique based on observations of scattering polarization in C2 molecular lines around 514.0 nm, taken with a cadence of approximately one month. Our results now span almost one complete solar cycle.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The solar photosphere is filled by magnetic fields tangled at scales much smaller than the resolution capability of solar telescopes. These hidden magnetic fields can be investigated via the Hanle effect. In 2007, we started a synoptic program to explore whether the magnetic flux of the quiet photosphere varies with the solar cycle. For this purpose we applied a differential Hanle effect technique based on observations of scattering polarization in C2 molecular lines around 514.0 nm, taken with a cadence of approximately one month. Our results now span almost one complete solar cycle. |
Bianda, M; Ramelli, R; Gisler, D; Belluzzi, L; Carlin, E ~S Second Solar Spectrum Observations with ZIMPOL Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 223, 2019. @inproceedings{2019ASPC..526..223B, title = {Second Solar Spectrum Observations with ZIMPOL}, author = {M {Bianda} and R {Ramelli} and D {Gisler} and L {Belluzzi} and E ~S {Carlin}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0223.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {223}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The observational activity of IRSOL takes advantage of the high-precision instrumentation available, and of the possibility to carry out programs requiring observing time spread over weeks or months. Particular attention is paid to scattering polarization signals modified by the Hanle effect in spectral lines. Several programs at IRSOL are also aimed at getting the technical know-how necessary to exploit the potentialities of the new generation of large-aperture solar telescopes, which will provide observations with unprecedented spatial and temporal resolution without sacrificing spectropolarimetric sensitivity. In this contribution, we provide a brief description of some projects that are presently carried out at IRSOL. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The observational activity of IRSOL takes advantage of the high-precision instrumentation available, and of the possibility to carry out programs requiring observing time spread over weeks or months. Particular attention is paid to scattering polarization signals modified by the Hanle effect in spectral lines. Several programs at IRSOL are also aimed at getting the technical know-how necessary to exploit the potentialities of the new generation of large-aperture solar telescopes, which will provide observations with unprecedented spatial and temporal resolution without sacrificing spectropolarimetric sensitivity. In this contribution, we provide a brief description of some projects that are presently carried out at IRSOL. |
Ramelli, R; Bianda, M; Setzer, M; Enegelhard, M; Paglia, F; Stenflo, J O; Küveler, G; Plewe, R Atlas of the Solar Intensity Spectrum and its Center-to-Limb Variation Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 287, 2019. @inproceedings{2019ASPC..526..287R, title = {Atlas of the Solar Intensity Spectrum and its Center-to-Limb Variation}, author = {R {Ramelli} and M {Bianda} and M {Setzer} and M {Enegelhard} and F {Paglia} and J O {Stenflo} and G {Küveler} and R {Plewe}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0287.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {287}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The solar limb darkening function is well known and is widely employed in models of the solar atmosphere. However, there has been a lack of systematic spectrally resolved measurements. Therefore we recently decided to start an observing campaign with the Gregory-Coudé Telescope at IRSOL in Locarno in order to produce a spectral atlas obtained at 10 different heliocentric angles θ, chosen so that μ = cos θ covers the interval from 0.1 to 1.0 in step of 0.1. The measurements carried out till now include the spectral range from 439 nm to 666 nm. The collected data provide information about the anisotropy of the emergent radiation field on the solar surface, allowing a better modeling of the Second Solar Spectrum. In addition the data give observational constraints that should be taken into account when modeling the solar atmosphere.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The solar limb darkening function is well known and is widely employed in models of the solar atmosphere. However, there has been a lack of systematic spectrally resolved measurements. Therefore we recently decided to start an observing campaign with the Gregory-Coudé Telescope at IRSOL in Locarno in order to produce a spectral atlas obtained at 10 different heliocentric angles θ, chosen so that μ = cos θ covers the interval from 0.1 to 1.0 in step of 0.1. The measurements carried out till now include the spectral range from 439 nm to 666 nm. The collected data provide information about the anisotropy of the emergent radiation field on the solar surface, allowing a better modeling of the Second Solar Spectrum. In addition the data give observational constraints that should be taken into account when modeling the solar atmosphere. |
Ishikawa, R; Trujillo Bueno, J; Uitenbroek, H; Kubo, M; Tsuneta, S; Goto, M; Kano, R; Narukage, N; Bando, T; Katsukawa, Y; Ishikawa, S; Giono, G; Suematsu, Y; Hara, H; Shimizu, T; Sakao, T; Winebarger, A; Kobayashi, K; Cirtain, J; Champey, P; `e}re, {Auch F; ě}pán, J {{Š}t; Belluzzi, L; Asensio Ramos, A; Manso Sainz, R; De Pomtieu, B; Ichimoto, K; Carlsson, M; Casini, R Comparison of Scattering Polarization Signals Observed by CLASP: Possible Indication of the Hanle Effect Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 305, 2019. @inproceedings{2019ASPC..526..305I, title = {Comparison of Scattering Polarization Signals Observed by CLASP: Possible Indication of the Hanle Effect}, author = {R {Ishikawa} and J {Trujillo Bueno} and H {Uitenbroek} and M {Kubo} and S {Tsuneta} and M {Goto} and R {Kano} and N {Narukage} and T {Bando} and Y {Katsukawa} and S {Ishikawa} and G {Giono} and Y {Suematsu} and H {Hara} and T {Shimizu} and T {Sakao} and A {Winebarger} and K {Kobayashi} and J {Cirtain} and P {Champey} and F {Auch{`e}re} and J {{Š}t{ě}pán} and L {Belluzzi} and A {Asensio Ramos} and R {Manso Sainz} and B {De Pomtieu} and K {Ichimoto} and M {Carlsson} and R {Casini}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0305.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {305}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the first time, the linear polarization produced by scattering processes in the hydrogen Lyman-ensuremathalpha (121.57 nm) and Si III (120.56 nm) lines of the solar disk radiation. The complexity of the observed scattering polarization (i.e., conspicuous spatial variations in Q/I and U/I at spatial scales of 10″–20″ and the absence of center-to- limb variation at the Lyman-ensuremathalpha center; see Kano et al. 2017) motivated us to search for possible hints of the operation of the Hanle effect by comparing: (a) the Lyman-ensuremathalpha line center signal, for which the critical field strength (B$_Ħ$) for the onset of the Hanle effect is 53 G, (b) the Lyman-ensuremathalpha wing, which is insensitive to the Hanle effect, and (c) the Si III line, whose B$_Ħ$ = 290 G. We focus on four regions with different total unsigned photospheric magnetic fluxes (estimated from SDO/HMI observations), and compare the corresponding U/I spatial variations in the Lyman-ensuremathalpha wing, Lyman-ensuremathalpha center, and Si III line. The U/I signal in the Lyman-ensuremathalpha wing shows an antisymmetric spatial distribution, which is caused by the presence of a bright structure in all the selected regions, regardless of the total unsigned photospheric magnetic flux. In an internetwork region, the Lyman-ensuremathalpha center shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si III line, the spatial variation of U/I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. We argue that a plausible explanation of this differential behavior is the operation of the Hanle effect. textbackslashtextbackslashThis work, presented in an oral contribution at this Workshop, has been published on The Astrophysical Journal (Ishikawa et al. 2017).}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the first time, the linear polarization produced by scattering processes in the hydrogen Lyman-ensuremathalpha (121.57 nm) and Si III (120.56 nm) lines of the solar disk radiation. The complexity of the observed scattering polarization (i.e., conspicuous spatial variations in Q/I and U/I at spatial scales of 10″–20″ and the absence of center-to- limb variation at the Lyman-ensuremathalpha center; see Kano et al. 2017) motivated us to search for possible hints of the operation of the Hanle effect by comparing: (a) the Lyman-ensuremathalpha line center signal, for which the critical field strength (B$_Ħ$) for the onset of the Hanle effect is 53 G, (b) the Lyman-ensuremathalpha wing, which is insensitive to the Hanle effect, and (c) the Si III line, whose B$_Ħ$ = 290 G. We focus on four regions with different total unsigned photospheric magnetic fluxes (estimated from SDO/HMI observations), and compare the corresponding U/I spatial variations in the Lyman-ensuremathalpha wing, Lyman-ensuremathalpha center, and Si III line. The U/I signal in the Lyman-ensuremathalpha wing shows an antisymmetric spatial distribution, which is caused by the presence of a bright structure in all the selected regions, regardless of the total unsigned photospheric magnetic flux. In an internetwork region, the Lyman-ensuremathalpha center shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si III line, the spatial variation of U/I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. We argue that a plausible explanation of this differential behavior is the operation of the Hanle effect. textbackslashtextbackslashThis work, presented in an oral contribution at this Workshop, has been published on The Astrophysical Journal (Ishikawa et al. 2017). |
Janett, G; Steiner, O; Belluzzi, L Numerical Methods for the Radiative Transfer Equation of Polarized Light Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 133, 2019. @inproceedings{2019ASPC..526..133J, title = {Numerical Methods for the Radiative Transfer Equation of Polarized Light}, author = {G {Janett} and O {Steiner} and L {Belluzzi}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0133.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {133}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The quest of the ``best formal solver'' available is still open and the lack of a clear comparison between the different numerical methods proposed by the community does not facilitate a conclusion. This work presents a reference paradigm for the characterization of formal solvers, based on the concepts of order of accuracy, stability and computational cost. This overview aims to facilitate the comprehension of the advantages and weaknesses of the already existing formal solvers and of those yet to come.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The quest of the ``best formal solver'' available is still open and the lack of a clear comparison between the different numerical methods proposed by the community does not facilitate a conclusion. This work presents a reference paradigm for the characterization of formal solvers, based on the concepts of order of accuracy, stability and computational cost. This overview aims to facilitate the comprehension of the advantages and weaknesses of the already existing formal solvers and of those yet to come. |
Alsina Ballester, E; Belluzzi, L; Trujillo Bueno, J The Transfer of Resonance Line Polarization with PRD in the General Hanle-Zeeman Regime Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 119, 2019. @inproceedings{2019ASPC..526..119A, title = {The Transfer of Resonance Line Polarization with PRD in the General Hanle-Zeeman Regime}, author = {E {Alsina Ballester} and L {Belluzzi} and J {Trujillo Bueno}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0119.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {119}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {We present numerical radiative transfer calculations of the four Stokes parameters of the radiation emerging from one-dimensional model atmospheres. In this investigation we account for the impact of partial frequency redistribution (PRD) in scattering and the joint action of the Hanle and Zeeman effects. Strong resonance lines of interest for chromospheric magnetic field diagnostics have been considered, namely the Ca I line at 4227 Å and the Mg II k line at 2795 Å. The Stokes profiles of these lines have been obtained by considering two-level atomic models, both in the absence and in the presence of magnetic fields. We draw attention to the fact that the magneto-optical terms of the transfer equations for Stokes Q and U are responsible for an interesting and previously unnoticed magnetic sensitivity of their scattering polarization profiles beyond the Doppler core. This important discovery contributes to paint a more detailed picture of the influence of relatively weak magnetic fields on the observable linear polarization signals of strong chromospheric lines, highlighting the importance of a PRD treatment for such lines.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } We present numerical radiative transfer calculations of the four Stokes parameters of the radiation emerging from one-dimensional model atmospheres. In this investigation we account for the impact of partial frequency redistribution (PRD) in scattering and the joint action of the Hanle and Zeeman effects. Strong resonance lines of interest for chromospheric magnetic field diagnostics have been considered, namely the Ca I line at 4227 Å and the Mg II k line at 2795 Å. The Stokes profiles of these lines have been obtained by considering two-level atomic models, both in the absence and in the presence of magnetic fields. We draw attention to the fact that the magneto-optical terms of the transfer equations for Stokes Q and U are responsible for an interesting and previously unnoticed magnetic sensitivity of their scattering polarization profiles beyond the Doppler core. This important discovery contributes to paint a more detailed picture of the influence of relatively weak magnetic fields on the observable linear polarization signals of strong chromospheric lines, highlighting the importance of a PRD treatment for such lines. |
Landi Degl'Innocenti, E; Belluzzi, L Relaxation Phenomena Due to Collisions with Neutral Perturbers in Hyperfine Structure Multiplets Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 29, 2019. @inproceedings{2019ASPC..526...29L, title = {Relaxation Phenomena Due to Collisions with Neutral Perturbers in Hyperfine Structure Multiplets}, author = {E {Landi Degl'Innocenti} and L {Belluzzi}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0029.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {29}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {A connection is established between the depolarizing rates, due to collisions with neutral perturbers, of the statistical tensors of a hyperfine structure multiplet and those of the statistical tensors of the parent fine structure level. This connection is described by a simple equation involving a 12-j symbol of the second kind. An application is performed to derive an analytical expression for the scattering matrix of a hyperfine structured two-level atom in the presence of collisions and a magnetic field. Numerical results are presented.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } A connection is established between the depolarizing rates, due to collisions with neutral perturbers, of the statistical tensors of a hyperfine structure multiplet and those of the statistical tensors of the parent fine structure level. This connection is described by a simple equation involving a 12-j symbol of the second kind. An application is performed to derive an analytical expression for the scattering matrix of a hyperfine structured two-level atom in the presence of collisions and a magnetic field. Numerical results are presented. |
McKenzie, D ~E; Ishikawa, R; Trujillo Bueno, J; Auchére, F; Rachmeler, L ~A; Kubo, M; Kobayashi, K; Winebarger, A ~R; Bethge, C ~W; Narukage, N; Kano, R; Ishikawa, S; de Pontieu, B; Carlsson, M; Yoshida, M; Belluzzi, L; ě}pán, J {{Š}t; del Pino Alemán, T; Alsina Ballester, E; Asensio Ramos, A CLASP2: The Chromospheric LAyer Spectro-Polarimeter Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 361, 2019. @inproceedings{2019ASPC..526..361M, title = {CLASP2: The Chromospheric LAyer Spectro-Polarimeter}, author = {D ~E {McKenzie} and R {Ishikawa} and J {Trujillo Bueno} and F {Auchére} and L ~A {Rachmeler} and M {Kubo} and K {Kobayashi} and A ~R {Winebarger} and C ~W {Bethge} and N {Narukage} and R {Kano} and S {Ishikawa} and B {de Pontieu} and M {Carlsson} and M {Yoshida} and L {Belluzzi} and J {{Š}t{ě}pán} and T {del Pino Alemán} and E {Alsina Ballester} and A {Asensio Ramos}}, editor = {L {Belluzzi} and R {Casini} and M {Romoli} and J {Trujillo Bueno}}, url = {http://aspbooks.org/custom/publications/paper/526-0361.html}, year = {2019}, date = {2019-05-01}, booktitle = {Astronomical Society of the Pacific Conference Series}, volume = {526}, pages = {361}, series = {Astronomical Society of the Pacific Conference Series}, abstract = {The hydrogen Lyman-ensuremathalpha line at 121.6 nm and the Mg k line at 279.5 nm are especially relevant for deciphering the magnetic structure of the chromosphere since their line-center signals are formed in the chromosphere and transition region, with unique sensitivities to magnetic fields. We propose the Chromospheric LAyer Spectro-Polarimeter (CLASP2), to build upon the success of the first CLASP flight, which measured the linear polarization in H I Lyman-ensuremathalpha. The existing CLASP instrument will be refitted to measure all four Stokes parameters in the 280 nm range, including variations due to the anisotropic radiation pumping, the Hanle effect, and the Zeeman effect.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The hydrogen Lyman-ensuremathalpha line at 121.6 nm and the Mg k line at 279.5 nm are especially relevant for deciphering the magnetic structure of the chromosphere since their line-center signals are formed in the chromosphere and transition region, with unique sensitivities to magnetic fields. We propose the Chromospheric LAyer Spectro-Polarimeter (CLASP2), to build upon the success of the first CLASP flight, which measured the linear polarization in H I Lyman-ensuremathalpha. The existing CLASP instrument will be refitted to measure all four Stokes parameters in the 280 nm range, including variations due to the anisotropic radiation pumping, the Hanle effect, and the Zeeman effect. |
Kumar Dhara, Sajal ; Capozzi, Emilia ; Gisler, Daniel ; Bianda, Michele ; Ramelli, Renzo ; Berdyugina, Svetlana ; Alsina, Ernest ; Belluzzi, Luca Spatial variations of the Sr I 4607 Åscattering polarization signals at subgranular scale observed with ZIMPOL at the GREGOR telescope Journal Article In: Nuovo Cimento C Geophysics Space Physics C, 42 (1), pp. 6, 2019. @article{2019NCimC..42....6K, title = {Spatial variations of the Sr I 4607 Åscattering polarization signals at subgranular scale observed with ZIMPOL at the GREGOR telescope}, author = {Sajal {Kumar Dhara} and Emilia {Capozzi} and Daniel {Gisler} and Michele {Bianda} and Renzo {Ramelli} and Svetlana {Berdyugina} and Ernest {Alsina} and Luca {Belluzzi}}, url = {https://arxiv.org/abs/1904.03986}, doi = {10.1393/ncc/i2019-19006-1}, year = {2019}, date = {2019-01-01}, journal = {Nuovo Cimento C Geophysics Space Physics C}, volume = {42}, number = {1}, pages = {6}, abstract = {Sr I 4607 Åspectral line shows one of the strongest scattering polarization signals in the visible solar spectrum. The amplitudes of these signals are expected to vary at granular spatial scales. This variation can be due to changes in the magnetic field intensity and orientation (Hanle effect) as well as due to spatial and temporal variations in the plasma properties. Measuring the spatial variation of such polarization signal are challenging since both high spatial resolution and high spectropolarimetric sensitivity are required at the same time. To the aim of measuring these spatial variations at granular scale, we carried out a spectro-polarimetric measurement with the Zurich IMaging POLarimeter (ZIMPOL), at the GREGOR solar telescope at different limb distances on solar disk. Our results show a spatial variation of scattering linear polarization signals in Sr I 4607 Åline at the granular scale at every ensuremathmu, starting from 0.2 to 0.8. The correlation between the scattering linear polarization signal amplitude and the continuum intensity imply statistically that the scattering polarization is higher at the granular regions than in the intergranular lanes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sr I 4607 Åspectral line shows one of the strongest scattering polarization signals in the visible solar spectrum. The amplitudes of these signals are expected to vary at granular spatial scales. This variation can be due to changes in the magnetic field intensity and orientation (Hanle effect) as well as due to spatial and temporal variations in the plasma properties. Measuring the spatial variation of such polarization signal are challenging since both high spatial resolution and high spectropolarimetric sensitivity are required at the same time. To the aim of measuring these spatial variations at granular scale, we carried out a spectro-polarimetric measurement with the Zurich IMaging POLarimeter (ZIMPOL), at the GREGOR solar telescope at different limb distances on solar disk. Our results show a spatial variation of scattering linear polarization signals in Sr I 4607 Åline at the granular scale at every ensuremathmu, starting from 0.2 to 0.8. The correlation between the scattering linear polarization signal amplitude and the continuum intensity imply statistically that the scattering polarization is higher at the granular regions than in the intergranular lanes. |
2018 |
Ramelli, Renzo; Cagnotti, Marco; Cortesi, Sergio; Bianda, Michele; Manna, Andrea Sunspot data collection of Specola Solare Ticinese in Locarno Conference Forthcoming Proceedings IAU Symposium , (340), IAU Proceedings Series IAU Publisher, Cambridge University Press , Forthcoming. @conference{ramelli_iaus340, title = {Sunspot data collection of Specola Solare Ticinese in Locarno}, author = {Renzo Ramelli and Marco Cagnotti and Sergio Cortesi and Michele Bianda and Andrea Manna}, url = {http://www.irsol.usi.ch/wp-content/uploads/2018/05/ramelli_iaus340.pdf http://arxiv.org/abs/1805.09202}, year = {2018}, date = {2018-05-23}, booktitle = {Proceedings IAU Symposium }, number = {340}, publisher = {IAU Publisher, Cambridge University Press }, series = {IAU Proceedings Series}, abstract = {Sunspot observations and counting are carried out at the Specola Solare Ticinese in Locarno since 1957 when it was built as an external observing station of the Zurich observatory. When in 1980 the data center responsibility was transferred from ETH Zurich to the Royal Observatory of Belgium in Brussels, the observations in Locarno continued and Specola Solare Ticinese got the role of pilot station. The data collected at Specola cover now the last 6 solar cycles. The aim of this presentation is to discuss and give an overview about the Specola data collection, the applied counting method and the future archiving projects. The latter includes the publication of all data and drawings in digital form in collaboration with the ETH Zurich University Archives, where a parallel digitization project is ongoing for the document of the former Swiss Federal Observatory in Zurich collected since the time of Rudolph Wolf. }, keywords = {}, pubstate = {forthcoming}, tppubtype = {conference} } Sunspot observations and counting are carried out at the Specola Solare Ticinese in Locarno since 1957 when it was built as an external observing station of the Zurich observatory. When in 1980 the data center responsibility was transferred from ETH Zurich to the Royal Observatory of Belgium in Brussels, the observations in Locarno continued and Specola Solare Ticinese got the role of pilot station. The data collected at Specola cover now the last 6 solar cycles. The aim of this presentation is to discuss and give an overview about the Specola data collection, the applied counting method and the future archiving projects. The latter includes the publication of all data and drawings in digital form in collaboration with the ETH Zurich University Archives, where a parallel digitization project is ongoing for the document of the former Swiss Federal Observatory in Zurich collected since the time of Rudolph Wolf. |
2017 |
Rachmeler, L; E McKenzie, D; Ishikawa, R; Trujillo Bueno, J; Auchère, F; Kobayashi, K; Winebarger, A; Bethge, C; Kano, R; Kubo, M; Song, D; Narukage, N; Ishikawa, S; De Pontieu, B; Carlsson, M; Yoshida, M; Belluzzi, L; Stepan, J; del Pino Alemná, T; Ballester, E A; Asensio Ramos, A CLASP2: The Chromospheric LAyer Spectro-Polarimeter Inproceedings In: AAS/Solar Physics Division Meeting, pp. 110.10, 2017. @inproceedings{2017SPD....4811010R, title = {CLASP2: The Chromospheric LAyer Spectro-Polarimeter}, author = {L {Rachmeler} and D {E McKenzie} and R {Ishikawa} and J {Trujillo Bueno} and F {Auchère} and K {Kobayashi} and A {Winebarger} and C {Bethge} and R {Kano} and M {Kubo} and D {Song} and N {Narukage} and S {Ishikawa} and B {De Pontieu} and M {Carlsson} and M {Yoshida} and L {Belluzzi} and J {Stepan} and T {del Pino Alemná} and E A {Ballester} and A {Asensio Ramos}}, url = {http://adsabs.harvard.edu/abs/2017SPD....4811010R}, year = {2017}, date = {2017-08-01}, booktitle = {AAS/Solar Physics Division Meeting}, volume = {48}, pages = {110.10}, series = {AAS/Solar Physics Division Meeting}, abstract = {We present the instrument, science case, and timeline of the CLASP2 sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha Spectro-Polarimeter) sounding rocket flight in 2015 resulted in the first-ever linear polarization measurements of solar hydrogen Lyman-alpha line, which is sensitive to the Hanle effect and can be used to constrain the magnetic field and geometric complexity of the upper chromosphere. Ly-alpha is one of several upper chromospheric lines that contain magnetic information. In the spring of 2019, we will re-fly the modified CLASP telescope to measure the full Stokes profile of Mg II h amp k near 280 nm. This set of lines is sensitive to the upper chromospheric magnetic field via both the Hanle and the Zeeman effects. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } We present the instrument, science case, and timeline of the CLASP2 sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha Spectro-Polarimeter) sounding rocket flight in 2015 resulted in the first-ever linear polarization measurements of solar hydrogen Lyman-alpha line, which is sensitive to the Hanle effect and can be used to constrain the magnetic field and geometric complexity of the upper chromosphere. Ly-alpha is one of several upper chromospheric lines that contain magnetic information. In the spring of 2019, we will re-fly the modified CLASP telescope to measure the full Stokes profile of Mg II h amp k near 280 nm. This set of lines is sensitive to the upper chromospheric magnetic field via both the Hanle and the Zeeman effects. |
Vigeesh, G; Steiner, O; Calvo, F; Roth, M On the effect of vorticity on the propagation of internal gravity waves. Inproceedings In: pp. 54, 2017. @inproceedings{2017MmSAI..88...54V, title = {On the effect of vorticity on the propagation of internal gravity waves.}, author = {G {Vigeesh} and O {Steiner} and F {Calvo} and M {Roth}}, year = {2017}, date = {2017-05-01}, journal = {Mem. Societa Astronomica Italiana}, volume = {88}, pages = {54}, abstract = {We compare different models of solar surface convection to study vorticity and how it can influence the propagation of internal gravity waves. We conclude that simulations performed with higher grid resolution may have a reduced gravity wave flux in the lower part of the atmosphere due to strong vorticity. We also show that the vertical extent of the allowed region of propagation depends on the magnetic field inclination. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } We compare different models of solar surface convection to study vorticity and how it can influence the propagation of internal gravity waves. We conclude that simulations performed with higher grid resolution may have a reduced gravity wave flux in the lower part of the atmosphere due to strong vorticity. We also show that the vertical extent of the allowed region of propagation depends on the magnetic field inclination. |
Steiner, O; Calvo, F; Salhab, R; G.Vigeesh, CO5BOLD for MHD: progresses and deficiencies . Inproceedings In: pp. 37, 2017. @inproceedings{2017MmSAI..88...37S, title = {CO5BOLD for MHD: progresses and deficiencies .}, author = {O. Steiner and F. Calvo and R. Salhab and G.Vigeesh}, year = {2017}, date = {2017-01-01}, journal = {Mem. Societa Astronomica Italiana}, volume = {88}, pages = {37}, abstract = {The magnetohydrodynamics module of CO5BOLD has been steadily improved over the past decade and has been used for various solar and stellar physical applications. We give an overview of current work with it and of remaining and newly emerged shortcomings. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The magnetohydrodynamics module of CO5BOLD has been steadily improved over the past decade and has been used for various solar and stellar physical applications. We give an overview of current work with it and of remaining and newly emerged shortcomings. |
2016 |
Wiehr E. Stellmacher, G; Bianda, M The Electron Density in a Quiescent Prominence Inproceedings In: pp. 79-85, 2016. @inproceedings{2016CEAB...40...79W, title = {The Electron Density in a Quiescent Prominence}, author = {Wiehr, E. Stellmacher, G. and Bianda, M.}, year = {2016}, date = {2016-02-01}, journal = {Central European Astrophysical Bulletin}, volume = {40}, pages = {79-85}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Stenflo, J O The Sun's spectrally resolved center-to-limb variation Inproceedings In: AAS/Solar Physics Division Meeting, pp. 12.08, 2016. @inproceedings{2016SPD....47.1208S, title = {The Sun's spectrally resolved center-to-limb variation}, author = {Stenflo, J.O.}, year = {2016}, date = {2016-01-01}, booktitle = {AAS/Solar Physics Division Meeting}, volume = {47}, pages = {12.08}, series = {AAS/Solar Physics Division Meeting}, abstract = {The center-to-limb variation (CLV) of the Sun's continuous spectrum is well known and has served as a major observational constraint on models of the solar atmosphere. The CLV however also varies dramatically with wavelength inside each spectral line. Here we report on two new atlases that show the properties of the CLV with high spectral resolution. One is a fully resolved spectral atlas from 4084 to 9950 AA of the ratio between the near limb spectrum, at 10 arcsec inside the limb, and the disk center spectrum, both recorded with the FTS at NSO/Kitt Peak. The other atlas gives the same kind of information but covers the whole range of limb distances by giving the ratio spectra for the nine $mu$ positions 0.1, 0.2, łdots, 0.9. This set of nine atlases for different $mu$ have been recorded over the last couple of years with the solar facility at IRSOL (Istituto Ricerche Solari Locarno) in Switzerland. We find that the CLV is spectrally as richly structured as the ordinary intensity spectrum, but the structuring is different and contains diagnostic information that is not contained in the intensity spectrum. Here we illustrate the properties of the new spectral structures and discuss what they mean. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The center-to-limb variation (CLV) of the Sun's continuous spectrum is well known and has served as a major observational constraint on models of the solar atmosphere. The CLV however also varies dramatically with wavelength inside each spectral line. Here we report on two new atlases that show the properties of the CLV with high spectral resolution. One is a fully resolved spectral atlas from 4084 to 9950 AA of the ratio between the near limb spectrum, at 10 arcsec inside the limb, and the disk center spectrum, both recorded with the FTS at NSO/Kitt Peak. The other atlas gives the same kind of information but covers the whole range of limb distances by giving the ratio spectra for the nine $mu$ positions 0.1, 0.2, łdots, 0.9. This set of nine atlases for different $mu$ have been recorded over the last couple of years with the solar facility at IRSOL (Istituto Ricerche Solari Locarno) in Switzerland. We find that the CLV is spectrally as richly structured as the ordinary intensity spectrum, but the structuring is different and contains diagnostic information that is not contained in the intensity spectrum. Here we illustrate the properties of the new spectral structures and discuss what they mean. |
2015 |
Smitha, H N; Nagendra, K N; Stenflo, J O; Bianda, M; Sampoorna, M; Ramelli, R A revisit to model the Cr i triplet at 5204-5208 Å and the Ba ii D2 line at 4554 Å in the Second Solar Spectrum Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 372-376, 2015. @inproceedings{2015IAUS..305..372S, title = {A revisit to model the Cr i triplet at 5204-5208 Å and the Ba ii D2 line at 4554 Å in the Second Solar Spectrum}, author = {Smitha, H.N. and Nagendra, K.N. and Stenflo, J.O. and Bianda, M. and Sampoorna, M. and Ramelli, R.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..372S}, doi = {10.1017/S1743921315005074}, year = {2015}, date = {2015-10-01}, booktitle = {Polarimetry}, volume = {305}, pages = {372-376}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Sowmya, K; Nagendra, K N; Sampoorna, M; Stenflo, J O Paschen-Back effect involving atomic fine and hyperfine structure states Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 154-158, 2015. @inproceedings{2015IAUS..305..154S, title = {Paschen-Back effect involving atomic fine and hyperfine structure states}, author = {Sowmya, K. and Nagendra, K.N. and Sampoorna, M. and Stenflo, J.O.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..154S}, doi = {10.1017/S1743921315004688}, year = {2015}, date = {2015-10-01}, booktitle = {Polarimetry}, volume = {305}, pages = {154-158}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Carlin, E S Chromospheric diagnosis with forward scattering polarization Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 146-153, 2015. @inproceedings{2015IAUS..305..146C, title = {Chromospheric diagnosis with forward scattering polarization}, author = {Carlin, E.S.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..146C}, doi = {10.1017/S1743921315004676}, year = {2015}, date = {2015-10-01}, booktitle = {Polarimetry}, volume = {305}, pages = {146-153}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Stenflo, J O Coherence structure of D1 scattering Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 136-145, 2015. @inproceedings{2015IAUS..305..136S, title = {Coherence structure of D1 scattering}, author = {Stenflo, J.O.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..136S}, doi = {10.1017/S1743921315004664}, year = {2015}, date = {2015-10-01}, booktitle = {Polarimetry}, volume = {305}, pages = {136-145}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Trujillo Bueno, J; Del Pino Alemán, T; Belluzzi, L Atomic Scattering Polarization. Observations, Modeling, Predictions Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 127-135, 2015. @inproceedings{2015IAUS..305..127T, title = {Atomic Scattering Polarization. Observations, Modeling, Predictions}, author = {Trujillo Bueno, J. and Del Pino Alemán, T. and Belluzzi, L.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..127B}, doi = {10.1017/S1743921315004652}, year = {2015}, date = {2015-10-01}, booktitle = {Polarimetry}, volume = {305}, pages = {127-135}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Supriya, H D; Smitha, H N; Nagendra, K N; Stenflo, J O; Bianda, M; Ravindra, B; Ramelli, R; Anusha, L S Modeling the center-to-limb variation of the Ca i 4227 Å line using FCHHT models Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 381-386, 2015. @inproceedings{2015IAUS..305..381S, title = {Modeling the center-to-limb variation of the Ca i 4227 Å line using FCHHT models}, author = {Supriya, H.D. and Smitha, H.N. and Nagendra, K.N. and Stenflo, J.O. and Bianda, M. and Ravindra, B. and Ramelli, R. and Anusha, L.S.}, editor = {Nagendra, K.N. and Bagnulo, S. and Centeno, R. and Martínez González, M.J.}, url = {http://adsabs.harvard.edu/abs/2015IAUS..305..381S}, doi = {10.1017/S1743921315005098}, year = {2015}, date = {2015-01-01}, booktitle = {Polarimetry}, volume = {305}, pages = {381-386}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2014 |
Smitha, H N; Nagendra, K N; Stenflo, J O; Sampoorna, M The Role of Quantum Interference and Partial Redistribution in the Solar Ba II D2 4554 Å Line Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 213, 2014. @inproceedings{2014ASPC..489..213S, title = {The Role of Quantum Interference and Partial Redistribution in the Solar Ba II D2 4554 Å Line}, author = {Smitha, H.N. and Nagendra, K.N. and Stenflo, J.O. and Sampoorna, M.}, editor = {Nagendra, K.N. and Stenflo, J.O. and Qu, Q. and Sampoorna, M.}, url = {http://adsabs.harvard.edu/abs/2014ASPC..489..213S}, year = {2014}, date = {2014-10-01}, booktitle = {Solar Polarization 7}, volume = {489}, pages = {213}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Bianda, M; Ramelli, R; Gisler, D; Stenflo, J O Solar Cycle Variations of the Second Solar Spectrum Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 167, 2014. @inproceedings{2014ASPC..489..167B, title = {Solar Cycle Variations of the Second Solar Spectrum}, author = {Bianda, M. and Ramelli, R. and Gisler, D. and Stenflo, J.O.}, editor = {Nagendra, K.N. and Stenflo, J.O. and Qu, Q. and Sampoorna, M.}, url = {https://www.irsol.usi.ch/data/Papers/SPW7-bianda_4.pdf}, year = {2014}, date = {2014-10-01}, booktitle = {Solar Polarization 7}, volume = {489}, pages = {167}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Landi Degl'Innocenti, E; Belluzzi, L Theoretical Schemes for the Interpretation of Solar Polarimetric Observations: An Overview and Some New Ideas Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 99, 2014. @inproceedings{2014ASPC..489...99L, title = {Theoretical Schemes for the Interpretation of Solar Polarimetric Observations: An Overview and Some New Ideas}, author = {Landi Degl'Innocenti, E. and Belluzzi, L.}, editor = {Nagendra, K.N. and Stenflo, J.O. and Qu, Q. and Sampoorna, M.}, url = {https://www.irsol.usi.ch/data/Papers/landi_belluzzi_spw7.pdf}, year = {2014}, date = {2014-10-01}, booktitle = {Solar Polarization 7}, volume = {489}, pages = {99}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Demidov, M L; Stenflo, J O; Bianda, M; Ramelli, R Conversion of the 6302 / 6301 Stokes V Line Ratio to the 5250 / 5247 Ratio for the Diagnostics of Quiet-Sun Magnetic Fields Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 21, 2014. @inproceedings{2014ASPC..489...21D, title = {Conversion of the 6302 / 6301 Stokes V Line Ratio to the 5250 / 5247 Ratio for the Diagnostics of Quiet-Sun Magnetic Fields}, author = {Demidov, M.L. and Stenflo, J.O. and Bianda, M. and Ramelli, R.}, editor = {Nagendra, K.N. and Stenflo, J.O. and Qu, Q. and Sampoorna, M.}, url = {http://adsabs.harvard.edu/abs/2014ASPC..489...21D}, year = {2014}, date = {2014-10-01}, booktitle = {Solar Polarization 7}, volume = {489}, pages = {21}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Stenflo, J O Nature of Quiet-Sun Magnetic Fields Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 3, 2014. @inproceedings{2014ASPC..489....3S, title = {Nature of Quiet-Sun Magnetic Fields}, author = {Stenflo, J.O.}, editor = {Nagendra, K.N. and Stenflo, J.O. and Qu, Q. and Sampoorna, M.}, url = {http://adsabs.harvard.edu/abs/2014ASPC..489....3S}, year = {2014}, date = {2014-10-01}, booktitle = {Solar Polarization 7}, volume = {489}, pages = {3}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Ramelli, R; Gisler, D; Bianda, M; Bello González, N; Berdyugina, S; Soltau, D First successful deployment of the ZIMPOL-3 system at the GREGOR telescope Inproceedings In: Ground-based and Airborne Instrumentation for Astronomy V, pp. 91473G, 2014. @inproceedings{2014SPIE.9147E..3GR, title = {First successful deployment of the ZIMPOL-3 system at the GREGOR telescope}, author = {Ramelli, R. and Gisler, D. and Bianda, M. and Bello González, N. and Berdyugina, S. and Soltau, D.}, url = {https://www.irsol.usi.ch/data/Papers/ramelli-spie14.pdf}, doi = {10.1117/12.2056934}, year = {2014}, date = {2014-01-01}, booktitle = {Ground-based and Airborne Instrumentation for Astronomy V}, volume = {9147}, pages = {91473G}, series = {procspie}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2013 |
Stenflo, J O Nature of the solar dynamo at small scales Inproceedings In: Kosovichev, A G; de Gouveia Dal Pino, E; Yan, Y (Ed.): Solar and Astrophysical Dynamos and Magnetic Activity, pp. 119-130, 2013. @inproceedings{2013IAUS..294..119S, title = {Nature of the solar dynamo at small scales}, author = {Stenflo, J.O.}, editor = {Kosovichev, A.G. and de Gouveia Dal Pino, E. and Yan, Y.}, url = {http://adsabs.harvard.edu/abs/2013IAUS..294..119S}, doi = {10.1017/S1743921313002342}, year = {2013}, date = {2013-07-01}, booktitle = {Solar and Astrophysical Dynamos and Magnetic Activity}, volume = {294}, pages = {119-130}, series = {IAU Symposium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Bianda, M; Ramelli, R; Stenflo, J; Berdyugina, S; Gisler, D; Defilippis, I; Bello González, N The project of installing a ZIMPOL 3 polarimeter at GREGOR in Tenerife Inproceedings In: pp. 413, 2013. @inproceedings{2013MmSAI..84..413B, title = {The project of installing a ZIMPOL 3 polarimeter at GREGOR in Tenerife}, author = {Bianda, M. and Ramelli, R. and Stenflo, J. and Berdyugina, S. and Gisler, D. and Defilippis, I. and Bello González, N.}, year = {2013}, date = {2013-01-01}, journal = {Mem. Societa Astronomica Italiana}, volume = {84}, pages = {413}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Wiehr, E; Stellmacher, G; Ramelli, R; Bianda, M The Hot Skin of Prominence Structures Inproceedings In: pp. 487-494, 2013. @inproceedings{2013CEAB...37..487W, title = {The Hot Skin of Prominence Structures}, author = {Wiehr, E. and Stellmacher, G. and Ramelli, R. and Bianda, M.}, url = {https://www.irsol.usi.ch/data/Papers/HvarVortrag12.pdf}, year = {2013}, date = {2013-01-01}, journal = {Central European Astrophysical Bulletin}, volume = {37}, pages = {487-494}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Setzer, M; Lübke, S; Küveler, G; Zuber, A; Bianda, M; Ramelli, R Computersteuerung für einen Sonnenspektrografen Inproceedings In: München DIV Deutscher Industrieverlag 2013, pp. 359, 2013. @inproceedings{Setzer2013, title = {Computersteuerung für einen Sonnenspektrografen}, author = {Setzer, M. and Lübke, S. and Küveler, G. and Zuber, A. and Bianda, M. and Ramelli, R.}, year = {2013}, date = {2013-01-01}, booktitle = {München DIV Deutscher Industrieverlag 2013}, pages = {359}, series = {Tagungsband AALE 2013}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2012 |
Frisch, H; Anusha, L S; Bianda, M; Holzreuter, R; Nagendra, K N; Ramelli, R; Sampoorna, M; Smitha, H N; Stenflo, J O Forward-scattering Hanle effect in the solar Ca i 4227 Å line Inproceedings In: Faurobert, M; Fang, C; Corbard, T (Ed.): EAS Publications Series, pp. 59-63, 2012. @inproceedings{2012EAS....55...59F, title = {Forward-scattering Hanle effect in the solar Ca i 4227 Å line}, author = {Frisch, H. and Anusha, L.S. and Bianda, M. and Holzreuter, R. and Nagendra, K.N. and Ramelli, R. and Sampoorna, M. and Smitha, H.N. and Stenflo, J.O.}, editor = {Faurobert, M. and Fang, C. and Corbard, T.}, url = {http://www.eas-journal.org/action/displayAbstract?fromPage=online&aid=8626040}, doi = {10.1051/eas/1255007}, year = {2012}, date = {2012-06-01}, booktitle = {EAS Publications Series}, volume = {55}, pages = {59-63}, series = {EAS Publications Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Sigismondi, C; Raponi, A; De Rosi, G; Bianda, M; Ramelli, R; Caccia, M; Maspero, M; Negrini, L; Wang, X Atmospheric fluctuations below 0.1 Hz during drift-scan solar diameter measurements Inproceedings In: Faurobert, M; Fang, C; Corbard, T (Ed.): EAS Publications Series, pp. 381-383, 2012. @inproceedings{2012EAS....55..381S, title = {Atmospheric fluctuations below 0.1 Hz during drift-scan solar diameter measurements}, author = {Sigismondi, C. and Raponi, A. and De Rosi, G. and Bianda, M. and Ramelli, R. and Caccia, M. and Maspero, M. and Negrini, L. and Wang, X.}, editor = {Faurobert, M. and Fang, C. and Corbard, T.}, url = {http://arxiv.org/abs/1112.6187}, doi = {10.1051/eas/1255054}, year = {2012}, date = {2012-01-01}, booktitle = {EAS Publications Series}, volume = {55}, pages = {381-383}, series = {EAS Publications Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Einarsen, L J; Rodenhuis, M; Snik, F; Keller, C U; Stam, D M; de Kok, R J; Bianda, M; Ramelli, R Multiwavelength imaging polarimetry of Venus at various phase angles Inproceedings In: Abbasi, A; Giesen, N (Ed.): EGU General Assembly Conference Abstracts, pp. 8670, 2012. @inproceedings{2012EGUGA..14.8670E, title = {Multiwavelength imaging polarimetry of Venus at various phase angles}, author = {Einarsen, L.J. and Rodenhuis, M. and Snik, F. and Keller, C.U. and Stam, D.M. and de Kok, R.J. and Bianda, M. and Ramelli, R.}, editor = {Abbasi, A. and Giesen, N.}, url = {http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012EGUGA..14.8670E&link_type=ARTICLE&db_key=AST&high=}, year = {2012}, date = {2012-01-01}, booktitle = {EGU General Assembly Conference Abstracts}, volume = {14}, pages = {8670}, series = {EGU General Assembly Conference Abstracts}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Setzer, M; Küveler, G; Zuber, A; Bianda, M; Ramelli, R Automatisierung eines Sonnenspektrografen Inproceedings In: VIP 2012, 2012. @inproceedings{Setzer2012, title = {Automatisierung eines Sonnenspektrografen}, author = {Setzer, M. and Küveler, G. and Zuber, A. and Bianda, M. and Ramelli, R.}, url = {https://www.irsol.usi.ch/data/Papers/setzer2012.pdf}, year = {2012}, date = {2012-01-01}, booktitle = {VIP 2012}, series = {Viruelle Instrumente in der Praxis}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2011 |
Stepan, J; Trujillo Bueno, J; Ramelli, R; Bianda, M Scattering polarization and the Hanle effect in Hα as a probe of chromospheric magnetism: Modeling vs. Observations Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 117, 2011. @inproceedings{2011ASPC..437..117S, title = {Scattering polarization and the Hanle effect in Hα as a probe of chromospheric magnetism: Modeling vs. Observations}, author = {Stepan, J. and Trujillo Bueno, J. and Ramelli, R. and Bianda, M.}, editor = {Kuhn, J.R. and Harrington, D.M. and Lin, H. and Berdyugina, S.V. and Trujillo-Bueno, J. and Keil, S.L. and Rimmele, T.}, url = {https://www.irsol.usi.ch/data/Papers/stepan_spw6.pdf}, year = {2011}, date = {2011-04-01}, booktitle = {Solar Polarization 6}, volume = {437}, pages = {117}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Ramelli, R; Trujillo Bueno, J; Bianda, M; Asensio Ramos, A Exploring the Magnetic Fields of Solar Prominences and Spicules via He I D3 spectropolarimetry Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 109, 2011. @inproceedings{2011ASPC..437..109R, title = {Exploring the Magnetic Fields of Solar Prominences and Spicules via He I D3 spectropolarimetry}, author = {Ramelli, R. and Trujillo Bueno, J. and Bianda, M. and Asensio Ramos, A.}, editor = {Kuhn, J.R. and Harrington, D.M. and Lin, H. and Berdyugina, S.V. and Trujillo-Bueno, J. and Keil, S.L. and Rimmele, T.}, url = {https://www.irsol.usi.ch/data/Papers/ramelli_spw6.pdf}, year = {2011}, date = {2011-04-01}, booktitle = {Solar Polarization 6}, volume = {437}, pages = {109}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Bianda, M; Ramelli, R; Stenflo, J O; Anusha, L S; Nagendra, K N; Sampoorna, M; Holzreuter, R; Frisch, H Observations of the solar Ca I 4227 Å line Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 67, 2011. @inproceedings{2011ASPC..437...67B, title = {Observations of the solar Ca I 4227 Å line}, author = {Bianda, M. and Ramelli, R. and Stenflo, J.O. and Anusha, L.S. and Nagendra, K.N. and Sampoorna, M. and Holzreuter, R. and Frisch, H.}, editor = {Kuhn, J.R. and Harrington, D.M. and Lin, H. and Berdyugina, S.V. and Trujillo-Bueno, J. and Keil, S.L. and Rimmele, T.}, url = {https://www.irsol.usi.ch/data/Papers/bianda_spw6.pdf}, year = {2011}, date = {2011-04-01}, booktitle = {Solar Polarization 6}, volume = {437}, pages = {67}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Anusha, L S; Stenflo, J O; Frisch, H; Bianda, M; Holzreuter, R; Nagendra, K N; Sampoorna, M; Ramelli, R Linear Polarization of the Solar Ca I 4227 Å Line: Modeling with Radiative Transfer and Last Scattering Approximation Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 57, 2011. @inproceedings{2011ASPC..437...57A, title = {Linear Polarization of the Solar Ca I 4227 Å Line: Modeling with Radiative Transfer and Last Scattering Approximation}, author = {Anusha, L.S. and Stenflo, J.O. and Frisch, H. and Bianda, M. and Holzreuter, R. and Nagendra, K.N. and Sampoorna, M. and Ramelli, R.}, editor = {Kuhn, J.R. and Harrington, D.M. and Lin, H. and Berdyugina, S.V. and Trujillo-Bueno, J. and Keil, S.L. and Rimmele, T.}, url = {https://www.irsol.usi.ch/data/Papers/anusha_spw6.pdf}, year = {2011}, date = {2011-04-01}, booktitle = {Solar Polarization 6}, volume = {437}, pages = {57}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Sigismondi, C; Raponi, A; Wang, X; De Rosi, G; Bianda, M; Ramelli, R The power spectrum of the seeing during solar observations Inproceedings In: 2011. @inproceedings{2011arXiv1112.0401S, title = {The power spectrum of the seeing during solar observations}, author = {Sigismondi, C. and Raponi, A. and Wang, X. and De Rosi, G. and Bianda, M. and Ramelli, R.}, url = {http://arxiv.org/abs/1112.0401}, year = {2011}, date = {2011-01-01}, journal = {ArXiv e-prints}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2010 |
Ramelli, R; Bucher, R; Rossini, L; Bianda, M; Balemi, S Adaptive optics system for the IRSOL solar observatory Inproceedings In: Adaptive Optics Systems II, pp. 77363K, 2010. @inproceedings{2010SPIE.7736E..3KR, title = {Adaptive optics system for the IRSOL solar observatory}, author = {Ramelli, R. and Bucher, R. and Rossini, L. and Bianda, M. and Balemi, S.}, url = {https://www.irsol.usi.ch/data/Papers/ao_spie10.pdf}, doi = {10.1117/12.857160}, year = {2010}, date = {2010-07-01}, booktitle = {Adaptive Optics Systems II}, volume = {7736}, pages = {77363K}, series = {procspie}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Ramelli, R; Balemi, S; Bianda, M; Defilippis, I; Gamma, L; Hagenbuch, S; Rogantini, M; Steiner, P; Stenflo, J O ZIMPOL-3: a powerful solar polarimeter Inproceedings In: Ground-based and Airborne Instrumentation for Astronomy III, pp. 77351Y, 2010. @inproceedings{2010SPIE.7735E..1YR, title = {ZIMPOL-3: a powerful solar polarimeter}, author = {Ramelli, R. and Balemi, S. and Bianda, M. and Defilippis, I. and Gamma, L. and Hagenbuch, S. and Rogantini, M. and Steiner, P. and Stenflo, J.O.}, url = {https://www.irsol.usi.ch/data/Papers/zimpol_spie10.pdf}, doi = {10.1117/12.857120}, year = {2010}, date = {2010-07-01}, booktitle = {Ground-based and Airborne Instrumentation for Astronomy III}, volume = {7735}, pages = {77351Y}, series = {procspie}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Kleint, L; Berdyugina, S V; Shapiro, A I; Bianda, M Turbulent Magnetic Fields in the Quiet Sun: A Search for Cyclic Variations Inproceedings In: Cranmer, S R; Hoeksema, J T; Kohl, J L (Ed.): SOHO-23: Understanding a Peculiar Solar Minimum, pp. 103, 2010. @inproceedings{2010ASPC..428..103K, title = {Turbulent Magnetic Fields in the Quiet Sun: A Search for Cyclic Variations}, author = {Kleint, L. and Berdyugina, S.V. and Shapiro, A.I. and Bianda, M.}, editor = {Cranmer, S.R. and Hoeksema, J.T. and Kohl, J.L.}, url = {https://www.irsol.usi.ch/data/Papers/asp428-103.pdf}, year = {2010}, date = {2010-06-01}, booktitle = {SOHO-23: Understanding a Peculiar Solar Minimum}, volume = {428}, pages = {103}, series = {Astronomical Society of the Pacific Conference Series}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Kleint, L; Berdyugina, S V; Gisler, D; Shapiro, A I; Bianda, M A synoptic program for large solar telescopes: Cyclic variation of turbulent magnetic fields Inproceedings In: pp. 644, 2010. @inproceedings{2010AN....331..644K, title = {A synoptic program for large solar telescopes: Cyclic variation of turbulent magnetic fields}, author = {Kleint, L. and Berdyugina, S.V. and Gisler, D. and Shapiro, A.I. and Bianda, M.}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/123537599/PDFSTART}, doi = {10.1002/asna.201011392}, year = {2010}, date = {2010-06-01}, journal = {Astronomische Nachrichten}, volume = {331}, pages = {644}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Conference Proceedings
2021 |
On the effect of oscillatory phenomena on Stokes inversion results Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200182, 2021. |
Acoustic-gravity wave propagation characteristics in three-dimensional radiation hydrodynamic simulations of the solar atmosphere Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200170, 2021. |
On the influence of magnetic topology on the propagation of internal gravity waves in the solar atmosphere Journal Article In: Philosophical Transactions of the Royal Society of London Series A, 379 (2190), pp. 20200177, 2021. |
2019 |
Solar Radio Observation Using CALLISTO at the USO/PRL, Udaipur Inproceedings In: 2019 IEEE MTT-S International Microwave and RF Conference (IMARC), pp. 1-6, 2019. |
Polarized Line Formation with Incomplete Paschen-Back Effect and Partial Frequency Redistribution Inproceedings In: Werner, K; Stehle, C; Rauch, T; Lanz, T (Ed.): Astronomical Society of the Pacific Conference Series, pp. 113, 2019. |
Effects of Angle-Dependent Partial Frequency Redistribution on Polarized Line Profiles Inproceedings In: Werner, K; Stehle, C; Rauch, T; Lanz, T (Ed.): Astronomical Society of the Pacific Conference Series, pp. 109, 2019. |
Measurement of the Evolution of the Magnetic Field of the Quiet Photosphere over a Solar Cycle Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 283, 2019. |
Second Solar Spectrum Observations with ZIMPOL Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 223, 2019. |
Atlas of the Solar Intensity Spectrum and its Center-to-Limb Variation Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 287, 2019. |
Comparison of Scattering Polarization Signals Observed by CLASP: Possible Indication of the Hanle Effect Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 305, 2019. |
Numerical Methods for the Radiative Transfer Equation of Polarized Light Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 133, 2019. |
The Transfer of Resonance Line Polarization with PRD in the General Hanle-Zeeman Regime Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 119, 2019. |
Relaxation Phenomena Due to Collisions with Neutral Perturbers in Hyperfine Structure Multiplets Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 29, 2019. |
CLASP2: The Chromospheric LAyer Spectro-Polarimeter Inproceedings In: Belluzzi, L; Casini, R; Romoli, M; Trujillo Bueno, J (Ed.): Astronomical Society of the Pacific Conference Series, pp. 361, 2019. |
Spatial variations of the Sr I 4607 Åscattering polarization signals at subgranular scale observed with ZIMPOL at the GREGOR telescope Journal Article In: Nuovo Cimento C Geophysics Space Physics C, 42 (1), pp. 6, 2019. |
2018 |
Sunspot data collection of Specola Solare Ticinese in Locarno Conference Forthcoming Proceedings IAU Symposium , (340), IAU Proceedings Series IAU Publisher, Cambridge University Press , Forthcoming. |
2017 |
CLASP2: The Chromospheric LAyer Spectro-Polarimeter Inproceedings In: AAS/Solar Physics Division Meeting, pp. 110.10, 2017. |
On the effect of vorticity on the propagation of internal gravity waves. Inproceedings In: pp. 54, 2017. |
CO5BOLD for MHD: progresses and deficiencies . Inproceedings In: pp. 37, 2017. |
2016 |
The Electron Density in a Quiescent Prominence Inproceedings In: pp. 79-85, 2016. |
The Sun's spectrally resolved center-to-limb variation Inproceedings In: AAS/Solar Physics Division Meeting, pp. 12.08, 2016. |
2015 |
A revisit to model the Cr i triplet at 5204-5208 Å and the Ba ii D2 line at 4554 Å in the Second Solar Spectrum Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 372-376, 2015. |
Paschen-Back effect involving atomic fine and hyperfine structure states Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 154-158, 2015. |
Chromospheric diagnosis with forward scattering polarization Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 146-153, 2015. |
Coherence structure of D1 scattering Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 136-145, 2015. |
Atomic Scattering Polarization. Observations, Modeling, Predictions Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 127-135, 2015. |
Modeling the center-to-limb variation of the Ca i 4227 Å line using FCHHT models Inproceedings In: Nagendra, K N; Bagnulo, S; Centeno, R; Martínez González, M J (Ed.): Polarimetry, pp. 381-386, 2015. |
2014 |
The Role of Quantum Interference and Partial Redistribution in the Solar Ba II D2 4554 Å Line Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 213, 2014. |
Solar Cycle Variations of the Second Solar Spectrum Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 167, 2014. |
Theoretical Schemes for the Interpretation of Solar Polarimetric Observations: An Overview and Some New Ideas Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 99, 2014. |
Conversion of the 6302 / 6301 Stokes V Line Ratio to the 5250 / 5247 Ratio for the Diagnostics of Quiet-Sun Magnetic Fields Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 21, 2014. |
Nature of Quiet-Sun Magnetic Fields Inproceedings In: Nagendra, K N; Stenflo, J O; Qu, Q; Sampoorna, M (Ed.): Solar Polarization 7, pp. 3, 2014. |
First successful deployment of the ZIMPOL-3 system at the GREGOR telescope Inproceedings In: Ground-based and Airborne Instrumentation for Astronomy V, pp. 91473G, 2014. |
2013 |
Nature of the solar dynamo at small scales Inproceedings In: Kosovichev, A G; de Gouveia Dal Pino, E; Yan, Y (Ed.): Solar and Astrophysical Dynamos and Magnetic Activity, pp. 119-130, 2013. |
The project of installing a ZIMPOL 3 polarimeter at GREGOR in Tenerife Inproceedings In: pp. 413, 2013. |
The Hot Skin of Prominence Structures Inproceedings In: pp. 487-494, 2013. |
Computersteuerung für einen Sonnenspektrografen Inproceedings In: München DIV Deutscher Industrieverlag 2013, pp. 359, 2013. |
2012 |
Forward-scattering Hanle effect in the solar Ca i 4227 Å line Inproceedings In: Faurobert, M; Fang, C; Corbard, T (Ed.): EAS Publications Series, pp. 59-63, 2012. |
Atmospheric fluctuations below 0.1 Hz during drift-scan solar diameter measurements Inproceedings In: Faurobert, M; Fang, C; Corbard, T (Ed.): EAS Publications Series, pp. 381-383, 2012. |
Multiwavelength imaging polarimetry of Venus at various phase angles Inproceedings In: Abbasi, A; Giesen, N (Ed.): EGU General Assembly Conference Abstracts, pp. 8670, 2012. |
Automatisierung eines Sonnenspektrografen Inproceedings In: VIP 2012, 2012. |
2011 |
Scattering polarization and the Hanle effect in Hα as a probe of chromospheric magnetism: Modeling vs. Observations Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 117, 2011. |
Exploring the Magnetic Fields of Solar Prominences and Spicules via He I D3 spectropolarimetry Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 109, 2011. |
Observations of the solar Ca I 4227 Å line Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 67, 2011. |
Linear Polarization of the Solar Ca I 4227 Å Line: Modeling with Radiative Transfer and Last Scattering Approximation Inproceedings In: Kuhn, J R; Harrington, D M; Lin, H; Berdyugina, S V; Trujillo-Bueno, J; Keil, S L; Rimmele, T (Ed.): Solar Polarization 6, pp. 57, 2011. |
The power spectrum of the seeing during solar observations Inproceedings In: 2011. |
2010 |
Adaptive optics system for the IRSOL solar observatory Inproceedings In: Adaptive Optics Systems II, pp. 77363K, 2010. |
ZIMPOL-3: a powerful solar polarimeter Inproceedings In: Ground-based and Airborne Instrumentation for Astronomy III, pp. 77351Y, 2010. |
Turbulent Magnetic Fields in the Quiet Sun: A Search for Cyclic Variations Inproceedings In: Cranmer, S R; Hoeksema, J T; Kohl, J L (Ed.): SOHO-23: Understanding a Peculiar Solar Minimum, pp. 103, 2010. |
A synoptic program for large solar telescopes: Cyclic variation of turbulent magnetic fields Inproceedings In: pp. 644, 2010. |