Abstract
State-of-the-art radial-velocity (RV) exoplanet searches are currently
limited by RV signals arising from stellar magnetic activity. We analyze
solar observations acquired over a 3 yr period during the decline of
Carrington Cycle 24 to test models of RV variation of Sun-like stars. A
purpose-built solar telescope at the High Accuracy Radial-velocity
Planet Searcher for the Northern hemisphere (HARPS-N) provides
disk-integrated solar spectra, from which we extract RVs and
{log}{R}HK}{\prime }. The Solar Dynamics
Observatory (SDO) provides disk-resolved images of magnetic activity.
The Solar Radiation and Climate Experiment (SORCE) provides
near-continuous solar photometry, analogous to a Kepler light curve. We
verify that the SORCE photometry and HARPS-N
{log}{R}HK}{\prime } correlate strongly with the
SDO-derived magnetic filling factor, while the HARPS-N RV variations do
not. To explain this discrepancy, we test existing models of RV
variations. We estimate the contributions of the suppression of
convective blueshift and the rotational imbalance due to brightness
inhomogeneities to the observed HARPS-N RVs. We investigate the time
variation of these contributions over several rotation periods, and how
these contributions depend on the area of active regions. We find that
magnetic active regions smaller than 60 Mm2 do not
significantly suppress convective blueshift. Our area-dependent model
reduces the amplitude of activity-induced RV variations by a factor of
two. The present study highlights the need to identify a proxy that
correlates specifically with large, bright magnetic regions on the
surfaces of exoplanet-hosting stars.
Original language | English |
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Number of pages | 12 |
Journal | The Astrophysical Journal |
Volume | 874 |
Issue number | 1 |
DOIs | |
Publication status | Published - 27 Mar 2019 |
Keywords
- planets and satellites: detection
- Sun: activity
- Sun: faculae
- plages
- Sun: granulation
- sunspots
- techniques: radial velocities
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Dive into the research topics of 'HARPS-N Solar RVs Are Dominated by Large, Bright Magnetic Regions'. Together they form a unique fingerprint.Student theses
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Understand thy star, understand thy planet
Costes, J. (Author), Watson, C. (Supervisor) & de Mooij, E. (Supervisor), Dec 2021Student thesis: Doctoral Thesis › Doctor of Philosophy
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