Solanki, Sami K.

[["dc.bibliographiccitation.firstpage","66"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","The Astrophysical Journal"],["dc.bibliographiccitation.volume","852"],["dc.contributor.author","Siu-Tapia, A. L."],["dc.contributor.author","Rempel, M."],["dc.contributor.author","Lagg, A."],["dc.contributor.author","Solanki, S. K."],["dc.date.accessioned","2020-12-10T18:47:34Z"],["dc.date.available","2020-12-10T18:47:34Z"],["dc.date.issued","2018"],["dc.identifier.doi","10.3847/1538-4357/aaa007"],["dc.identifier.eissn","1538-4357"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/78808"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Evershed and Counter-Evershed Flows in Sunspot MHD Simulations"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","A4"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","596"],["dc.contributor.author","Franz, M."],["dc.contributor.author","Collados, M."],["dc.contributor.author","Bethge, C."],["dc.contributor.author","Schlichenmaier, R."],["dc.contributor.author","Borrero, J. M."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Lagg, A."],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","Berkefeld, T."],["dc.contributor.author","Kiess, C."],["dc.contributor.author","Rezaei, R."],["dc.contributor.author","Schmidt, Christian D."],["dc.contributor.author","Sigwarth, M."],["dc.contributor.author","Soltau, D."],["dc.contributor.author","Volkmer, R."],["dc.contributor.author","Luhe, O. von der"],["dc.contributor.author","Waldmann, T."],["dc.contributor.author","Orozco, D."],["dc.contributor.author","Pastor Yabar, A."],["dc.contributor.author","Denker, C."],["dc.contributor.author","Balthasar, H."],["dc.contributor.author","Staude, J."],["dc.contributor.author","Hofmann, A."],["dc.contributor.author","Strassmeier, K."],["dc.contributor.author","Feller, A."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Sobotka, M."],["dc.date.accessioned","2020-07-01T07:16:29Z"],["dc.date.available","2020-07-01T07:16:29Z"],["dc.date.issued","2016"],["dc.description.abstract","Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and three-lobed Stokes V profiles. Infrared lines probe a narrow layer in the very deep photosphere, providing the possibility of directly measuring the orientation of magnetic fields close to the solar surface. Aims. We study the topology of the penumbral magnetic field in the lower photosphere, focusing on regions where it returns below the surface. Methods. We analyzed 71 spectropolarimetric datasets from Hinode and from the GREGOR infrared spectrograph. We inferred the quality and polarimetric accuracy of the infrared data after applying several reduction steps. Techniques of spectral inversion and forward synthesis were used to test the detection algorithm. We compared the morphology and the fractional penumbral area covered by reversed-polarity and three-lobed Stokes V profiles for sunspots at disk center. We determined the amount of reversed-polarity and three-lobed Stokes V profiles in visible and infrared data of sunspots at various heliocentric angles. From the results, we computed center-to-limb variation curves, which were interpreted in the context of existing penumbral models. Results. Observations in visible and near-infrared spectral lines yield a significant difference in the penumbral area covered by magnetic fields of opposite polarity. In the infrared, the number of reversed-polarity Stokes V profiles is smaller by a factor of two than in the visible. For three-lobed Stokes V profiles the numbers differ by up to an order of magnitude."],["dc.identifier.arxiv","1608.00513v2"],["dc.identifier.doi","10.1051/0004-6361/201628407"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/66810"],["dc.language.iso","en"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.title","Magnetic fields of opposite polarity in sunspot penumbrae"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","A17"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","653"],["dc.contributor.author","Saranathan, S."],["dc.contributor.author","van Noort, M."],["dc.contributor.author","Solanki, S. K."],["dc.date.accessioned","2021-10-01T09:57:47Z"],["dc.date.available","2021-10-01T09:57:47Z"],["dc.date.issued","2021"],["dc.description.abstract","Context. A long-standing issue in solar ground-based observations has been the contamination of data due to stray light, which is particularly relevant in inversions of spectropolarimetric data. Aims. We aim to build on a statistical method of correcting stray-light contamination due to residual high-order aberrations and apply it to ground-based slit spectra. Methods. The observations were obtained at the Swedish Solar Telescope, and restored using the multi-frame blind deconvolution restoration procedure. Using the statistical properties of seeing, we created artificially degraded synthetic images generated from magneto-hydrodynamic simulations. We then compared the synthetic data with the observations to derive estimates of the amount of the residual stray light in the observations. In the final step, the slit spectra were deconvolved with a stray-light point spread function to remove the residual stray light from the observations. Results. The RMS granulation contrasts of the deconvolved spectra were found to increase to approximately 12.5%, from 9%. Spectral lines, on average, were found to become deeper in the granules and shallower in the inter-granular lanes, indicating systematic changes to gradients in temperature. The deconvolution was also found to increase the redshifts and blueshifts of spectral lines, suggesting that the velocities of granulation in the solar photosphere are higher than had previously been observed."],["dc.identifier.doi","10.1051/0004-6361/201937100"],["dc.identifier.pii","aa37100-19"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/89913"],["dc.notes.intern","DOI Import GROB-469"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.title","Correction of atmospheric stray light in restored slit spectra"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","A11"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","642"],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","del Toro Iniesta, J. C."],["dc.contributor.author","Woch, J."],["dc.contributor.author","Gandorfer, A."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Alvarez-Herrero, A."],["dc.contributor.author","Appourchaux, T."],["dc.contributor.author","Martínez Pillet, V."],["dc.contributor.author","Pérez-Grande, I."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Lange, T."],["dc.contributor.author","Müller, D."],["dc.contributor.author","Gizon, Laurent"],["dc.contributor.author","Müller, R."],["dc.contributor.author","Albert, K."],["dc.contributor.author","Löptien, Björn"],["dc.contributor.author","Meyer, S."],["dc.contributor.author","Soltau, D."],["dc.contributor.author","Schou, Jesper"],["dc.date.accessioned","2021-03-05T08:58:36Z"],["dc.date.available","2021-03-05T08:58:36Z"],["dc.date.issued","2020"],["dc.identifier.doi","10.1051/0004-6361/201935325"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/80195"],["dc.notes.intern","DOI Import GROB-393"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.title","The Polarimetric and Helioseismic Imager on Solar Orbiter"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","A69"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","636"],["dc.contributor.author","Amazo-Gómez, E. M."],["dc.contributor.author","Shapiro, A. I."],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","Krivova, N. A."],["dc.contributor.author","Kopp, G."],["dc.contributor.author","Reinhold, T."],["dc.contributor.author","Oshagh, M."],["dc.contributor.author","Reiners, A."],["dc.date.accessioned","2021-04-14T08:26:43Z"],["dc.date.available","2021-04-14T08:26:43Z"],["dc.date.issued","2020"],["dc.identifier.doi","10.1051/0004-6361/201936925"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/82050"],["dc.notes.intern","DOI Import GROB-399"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.title","Inflection point in the power spectrum of stellar brightness variations"],["dc.title.alternative","II. The Sun"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","5"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","The Astrophysical Journal. Supplement Series"],["dc.bibliographiccitation.volume","233"],["dc.contributor.author","Gorobets, A. Y."],["dc.contributor.author","Berdyugina, S. V."],["dc.contributor.author","Riethmüller, T. L."],["dc.contributor.author","Rodríguez, J. Blanco"],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","Barthol, P."],["dc.contributor.author","Gandorfer, A."],["dc.contributor.author","Gizon, Laurent"],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Noort, M. van"],["dc.contributor.author","Del Toro Iniesta, J. C."],["dc.contributor.author","Suárez, D. Orozco"],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Pillet, V. Martínez"],["dc.contributor.author","Knölker, M."],["dc.date.accessioned","2020-12-10T18:47:36Z"],["dc.date.available","2020-12-10T18:47:36Z"],["dc.date.issued","2017"],["dc.identifier.doi","10.3847/1538-4365/aa8ef8"],["dc.identifier.eissn","1538-4365"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/78820"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","The Maximum Entropy Limit of Small-scale Magnetic Field Fluctuations in the Quiet Sun"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","28"],["dc.bibliographiccitation.issue","S327"],["dc.bibliographiccitation.journal","Proceedings of the International Astronomical Union"],["dc.bibliographiccitation.lastpage","33"],["dc.bibliographiccitation.volume","12"],["dc.contributor.author","Manrique, S. J. González"],["dc.contributor.author","Denker, C."],["dc.contributor.author","Kuckein, C."],["dc.contributor.author","Yabar, A. Pastor"],["dc.contributor.author","Collados, M."],["dc.contributor.author","Verma, M."],["dc.contributor.author","Balthasar, H."],["dc.contributor.author","Diercke, A."],["dc.contributor.author","Fischer, C. E."],["dc.contributor.author","Gömöry, P."],["dc.contributor.author","González, N. Bello"],["dc.contributor.author","Schlichenmaier, R."],["dc.contributor.author","Armas, M. Cubas"],["dc.contributor.author","Berkefeld, T."],["dc.contributor.author","Feller, A."],["dc.contributor.author","Hoch, S."],["dc.contributor.author","Hofmann, A."],["dc.contributor.author","Lagg, A."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Suárez, D. Orozco"],["dc.contributor.author","Schmidt, D."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Sigwarth, M."],["dc.contributor.author","Sobotka, M."],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","Soltau, D."],["dc.contributor.author","Staude, J."],["dc.contributor.author","Strassmeier, K. G."],["dc.contributor.author","Volkmer, R."],["dc.contributor.author","von der Lühe, O."],["dc.contributor.author","Waldmann, T."],["dc.date.accessioned","2020-12-10T15:22:25Z"],["dc.date.available","2020-12-10T15:22:25Z"],["dc.date.issued","2017"],["dc.identifier.doi","10.1017/S1743921317000278"],["dc.identifier.eissn","1743-9221"],["dc.identifier.issn","1743-9213"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/73394"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Flows along arch filaments observed in the GRIS ‘very fast spectroscopic mode’"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","L13"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","The Astrophysical Journal"],["dc.bibliographiccitation.volume","776"],["dc.contributor.author","Riethmüller, T. L."],["dc.contributor.author","Solanki, Sami K."],["dc.contributor.author","Hirzberger, Johann"],["dc.contributor.author","Danilovic, S."],["dc.contributor.author","Barthol, P."],["dc.contributor.author","Berkefeld, T."],["dc.contributor.author","Gandorfer, Achim"],["dc.contributor.author","Gizon, Laurent"],["dc.contributor.author","Knölker, M."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Toro Iniesta, J. C. del"],["dc.date.accessioned","2017-09-07T11:48:42Z"],["dc.date.available","2017-09-07T11:48:42Z"],["dc.date.issued","2013"],["dc.identifier.doi","10.1088/2041-8205/776/1/l13"],["dc.identifier.gro","3147034"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/4768"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","chake"],["dc.publisher","IOP Publishing"],["dc.relation.issn","2041-8205"],["dc.title","FIRST HIGH-RESOLUTION IMAGES OF THE SUN IN THE 2796 Å Mg II k LINE"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1009"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","The Astrophysical Journal"],["dc.bibliographiccitation.lastpage","1019"],["dc.bibliographiccitation.volume","589"],["dc.contributor.author","Gizon, L."],["dc.contributor.author","Solanki, S. K."],["dc.date.accessioned","2017-09-07T11:49:45Z"],["dc.date.available","2017-09-07T11:49:45Z"],["dc.date.issued","2003"],["dc.description.abstract","Asteroseismology provides us with the possibility of determining the angle, i, between the direction of the rotation axis of a pulsating Sun-like star and the line of sight. A knowledge of i is important not just for obtaining improved stellar parameters, but also in order to determine the true masses of extrasolar planets detected from the radial velocity shifts of their central stars. By means of Monte Carlo simulations, we estimate the precision of the measurement of i and other stellar parameters. We find that the inclination angle can be retrieved accurately when i gsim 30° for stars that rotate at least twice as fast as the Sun."],["dc.identifier.doi","10.1086/374715"],["dc.identifier.gro","3147431"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5008"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","0004-637X"],["dc.title","Determining the Inclination of the Rotation Axis of a Sun‐like Star"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A157"],["dc.bibliographiccitation.journal","Astronomy & Astrophysics"],["dc.bibliographiccitation.volume","627"],["dc.contributor.author","Cernetic, M."],["dc.contributor.author","Shapiro, A. I."],["dc.contributor.author","Witzke, V."],["dc.contributor.author","Krivova, N. A."],["dc.contributor.author","Solanki, S. K."],["dc.contributor.author","Tagirov, R. V."],["dc.date.accessioned","2019-08-01T08:39:30Z"],["dc.date.available","2019-08-01T08:39:30Z"],["dc.date.issued","2019"],["dc.description.abstract","Contex. Stellar spectra synthesis is essential for the characterization of potential planetary hosts. In addition, comprehensive stellar variability calculations with fast radiative transfer are needed to disentangle planetary transits from stellar magnetically-driven variability. The planet-hunting space telescopes, such as CoRoT, Kepler, and TESS will bring vast quantities of data, rekindling the interest in fast calculations of the radiative transfer. Aims. We revisit the Opacity Distribution Functions (ODF) approach routinely applied to speedup stellar spectral synthesis. To achieve a considerable speedup relative to the current state-of-the-art, we further optimize the approach and search for the best ODF configuration. Furthermore, we generalize the ODF approach for fast calculations of flux in various filters often used in stellar observations. Methods. In a parameter-sweep-fashion, we generated ODF in the spectral range from UV to IR with different setups. The most accurate ODF configuration for each spectral interval was determined. For calculations of the radiative fluxes through filters we adapted the wavelength grid based on the transmission curve, whereafter the normal ODF procedure was performed. Results. Our optimum ODF configuration allows for a three fold speedup, compared to the previously used ODF configurations. The ODF generalization to calculate fluxes through filters results in a speedup of more than two orders of magnitude."],["dc.identifier.arxiv","1906.03112v2"],["dc.identifier.doi","10.1051/0004-6361/201935723"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/62252"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.issn","0004-6361"],["dc.relation.issn","1432-0746"],["dc.title","Opacity distribution functions for stellar spectra synthesis"],["dc.type","journal_article"],["dc.type.internalPublication","no"],["dspace.entity.type","Publication"]]