| Name: Parvathy Menon |
| Affiliation: Indian Institute of Astrophysics, Bengaluru |
| Conference ID: ASI2026_786 |
| Title: Characterisation of Magnetic Activity on the Sun Using Disc-integrated Spectra |
| Abstract Type: Poster |
| Abstract Category: Sun, Solar System, Exoplanets, and Astrobiology |
| Author(s) and Co-Author(s) with Affiliation: Parvathy Menon(Indian Institute of Astrophysics, Bengaluru - 560034, India), S P Rajaguru(Indian Institute of Astrophysics, Bengaluru - 560034, India), Anisha Sen(Indian Institute of Astrophysics, Bengaluru - 560034, India), T Sivarani(Indian Institute of Astrophysics, Bengaluru - 560034, India) |
| Abstract: Stellar surface inhomogeneities due to magnetic structures such as spots, plages, and faculae are well recognized as sources of “noise” affecting accurate retrieval of exoplanet properties in stellar radial-velocity measurements. High-energy events, such as solar flares and coronal mass ejections, also leave characteristic signatures in the activity indices derivable from various spectral lines. In this work, we investigate activity-related features seen in the disk-integrated spectra of the Sun using time series of Sun-as-a-star spectral observations by HARPS-N. We trace the temporal evolution of various chromospheric and photospheric lines and the trend of these line indices with sunspot and plage fill factors to identify signatures of high-energy solar events and solar cycle variations in the spectral indices, which in turn help us understand such variations in sun-like exoplanet host stars. We have also calculated the correlation of the S-index with the indices of Balmer lines of varying core width. We examined this behavior to understand the contributions of differences in Hα formation height variations, which affect the Hα and the S-index correlations that have been reported in studies of solar-like stars. To aid the interpretation of the observed behavior, we have also attempted to compare the Sun-as-a-star measurements with synthetic Hα and Ca II 8542 line profiles obtained from realistic 3D radiative magnetohydrodynamic (rMHD) simulations of enhanced network regions. |
