Leveraging Space-based Data from the Nearest Solar-Type Star to Better Understand Stellar Activity Signatures in Radial Velocity Data

Tamar Ervin, Samuel Halverson, Abigail Burrows, Neil Murphy, Arpita Roy, Raphaelle D. Haywood, Federica Rescigno, Chad F. Bender, Andrea S.J. Lin, Jennifer Burt, Suvrath Mahadevan

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Stellar variability is a key obstacle in reaching the sensitivity required to recover Earth-like exoplanetary signals using the radial velocity (RV) detection method. To explore activity signatures in Sun-like stars, we present SolAster, a publicly distributed analysis pipeline1010 https://tamarervin.github.io/SolAster/ that allows for comparison of space-based measurements with ground-based disk-integrated RVs. Using high-spatial-resolution Dopplergrams, magnetograms, and continuum filtergrams from the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory (SDO), we estimate "Sun-As-A-star"disk-integrated RVs due to rotationally modulated flux imbalances and convective blueshift suppression, as well as other observables such as unsigned magnetic flux. Comparing these measurements with ground-based RVs from the NEID instrument, which observes the Sun daily using an automated solar telescope, we find a strong relationship between magnetic activity indicators and RV variation, supporting efforts to examine unsigned magnetic flux as a proxy for stellar activity in slowly rotating stars. Detrending against measured unsigned magnetic flux allows us to improve the NEID RV measurements by a1/420% (a1/450 cm s-1 in a quadrature sum), yielding an rms scatter of a1/460 cm s-1 over five months. We also explore correlations between individual and averaged spectral line shapes in the NEID spectra and SDO-derived magnetic activity indicators, motivating future studies of these observables. Finally, applying SolAster to archival planetary transits of Venus and Mercury, we demonstrate the ability to recover small amplitude (<50 cm s-1) RV variations in the SDO data by directly measuring the Rossiter-McLaughlin signals.

Original languageEnglish (US)
Article number272
JournalAstronomical Journal
Volume163
Issue number6
DOIs
StatePublished - Jun 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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