20 citations · 169 across the 17 of their papers we have counts for
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Sensitivity of spectral lines to granulation: The Sun
K. Sowmya, A. I. Shapiro, V. Vasilyev +3
The intrinsic variability of stars, due to acoustic oscillations, surface granulation, and magnetic activity, introduces radial velocity (RV) jitter in spectral lines, obscuring tr…
Solar variability in the Mg II h and k lines
K. Sowmya, M. Snow, A. I. Shapiro +3
Solar irradiance and its variations in the ultraviolet (UV) control the photochemistry in Earth's atmosphere and influence Earth's climate. The variability of Mg II h and k core-to…
Modeling Stellar CaII H & K Emission Variations: Spot Contribution to the S-index
K. Sowmya, A. I. Shapiro, L. H. M. Rouppe van der Voort +2
The S-index is a measure of emission in the CaII H & K lines and is a widely used proxy of stellar magnetic activity. It has been assumed until now that the S-index is mainly affec…
Faculae cancel out on the surfaces of active Suns
N. -E. Nèmec, A. I. Shapiro, E. Işık +5
Surfaces of the Sun and other cool stars are filled with magnetic fields, which are either seen as dark compact spots or more diffuse bright structures like faculae. Both hamper de…
Predictions of Astrometric Jitter for Sun-like Stars. III. Fast Rotators
K. Sowmya, N. -E. Nèmec, A. I. Shapiro +3
A breakthrough in exoplanet detections is foreseen with the unprecedented astrometric measurement capabilities offered by instrumentation aboard Gaia space observatory. Besides, as…
Magnetized supersonic downflows in the chromosphere. A statistical study using the He I 10830 Å lines
K. Sowmya, A. Lagg, S. K. Solanki +1
The chromosphere above active regions (ARs) on the Sun hosts magnetized supersonic downflows. Studies of these supersonic downflows help to decipher the magnetic fine structure and…
Predictions of Astrometric Jitter for Sun-like Stars. II. Dependence on Inclination, Metallicity, and Active-Region Nesting
K. Sowmya, N. -E. Nèmec, A. I. Shapiro +5
Ultra-precise astrometry from the Gaia mission is expected to lead to astrometric detections of more than 20,000 exoplanets in our Galaxy. One of the factors that could hamper such…
Modeling stellar Ca II H & K emission variations. I. Effect of inclination on the S-index
K. Sowmya, A. I. Shapiro, V. Witzke +5
The emission in the near ultraviolet Ca II H & K lines is modulated by stellar magnetic activity. Although this emission, quantified via the S-index, has been serving as a prime pr…
Importance of Angle-dependent Partial Frequency Redistribution in Hyperfine Structure Transitions Under Incomplete Paschen-Back Effect Regime
K. N. Nagendra, K. Sowmya, M. Sampoorna +2
Angle-frequency coupling in scattering of polarized light on atoms is represented by the angle-dependent (AD) partial frequency redistribution (PRD) matrices. There are several lin…
Solar-type Stars Observed by LAMOST and Kepler
Jinghua Zhang, Alexander I. Shapiro, Shaolan Bi +8
Obtaining measurements of chromospheric and photometric activity of stars with near-solar fundamental parameters and rotation periods is important for a better understanding of sol…
Fast downflows in a chromospheric filament
K. Sowmya, A. Lagg, S. K. Solanki +1
An active region filament in the upper chromosphere is studied using spectropolarimetric data in He I 10830 A from the GREGOR telescope. A Milne-Eddingon based inversion of the Unn…
Polarized Line Formation in Arbitrary Strength Magnetic Fields: the case of a two-level atom with hyperfine structure splitting
M. Sampoorna, K. N. Nagendra, K. Sowmya +2
Quantum interference effects together with partial frequency redistribution (PFR) in line scattering produce subtle signatures in the so called Second Solar Spectrum (the linearly…
Polarized scattering of light for arbitrary magnetic fields with level-crossings from the combination of hyperfine and fine structure splittings
K. Sowmya, K. N. Nagendra, M. Sampoorna +1
Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the…
Polarized scattering with Paschen-Back effect, hyperfine structure, and partial frequency redistribution in magnetized stellar atmospheres
K. Sowmya, K. N. Nagendra, J. O. Stenflo +1
-state interference significantly modifies the polarization produced by scattering processes in the solar atmosphere. Its signature in the emergent Stokes spectrum in the absenc…
Blend lines in the polarized spectrum of the Sun
K. Sowmya, K. N. Nagendra, M. Sampoorna
Blend lines form an integral part of the theoretical analysis and modeling of the polarized spectrum of the Sun. Their interaction with other spectral lines needs to be explored an…
Polarized light scattering with Paschen-Back effect, level-crossing of fine structure states and partial frequency redistribution
K. Sowmya, K. N. Nagendra, M. Sampoorna +1
The quantum interference between the fine structure states of an atom modifies the shapes of the emergent Stokes profiles in the Second Solar Spectrum. This phenomenon has been stu…
Polarized line transfer with F-state interference in a non-magnetic medium: Partial frequency redistribution effects in the collisionless regime
H. N. Smitha, K. Sowmya, K. N. Nagendra +2
Quantum interference phenomena manifests itself in several ways in the polarized solar spectrum formed due to coherent scattering processes. One such effect arises due to interfere…