Photometry as a proxy for stellar activity in radial velocity analyses

Abstract

Stellar activity remains a limiting factor in measuring precise planet parameters from radial velocity spectroscopy, not least in the search for Earth mass planets orbiting in the habitable zones of Sun-like stars. One approach to mitigate stellar activity is to use combined analyses of both radial velocity and time-series photometry. We present an analysis of simultaneous disk-integrated photometry and radial velocity data of the Sun in order to determine the useful limits of a combined analysis. We find that simple periodogram or autocorrelation analysis of solar photometry give the correct rotation period <50% of the time. We therefore use a Gaussian process to investigate the time variability of solar photometry and to directly compare simultaneous photometry with radial velocity data. We find that the hyperparameter posteriors are relatively stable over 70 years of solar photometry and the amplitude tracks the solar cycle. We observe good agreement between the hyperparameter posteriors for the simultaneous photometry and radial velocity data. Our primary conclusion is a recommendation to include an additional prior in Gaussian process fits to constrain the evolutionary timescale to be greater than the recurrence timescale (ie., the rotation period) to recover more physically plausible and useful results. Our results indicate that such simultaneous monitoring may be a useful tool in enhancing the precision of radial velocity surveys.

10 pages, accepted in AJ

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Cited by in corpus (10)

• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• Quasi-periodic Gaussian Processes for stellar activity: from physical to kernel parameters
• Revisiting WASP-47 with ESPRESSO and TESS
• Where have all the solar-like stars gone? Rotation period detectability at various inclinations and metallicities
• K2-138 g: Spitzer Spots a Sixth Planet for the Citizen Science System
• EXPRES. II. Searching for Planets Around Active Stars: A Case Study of HD 101501
• Into the Depths: a new activity metric for high-precision radial velocity measurements based on line depth variations
• The California-Kepler Survey. XI. A Survey of Chromospheric Activity Through the Lens of Precise Stellar Properties
• Revisiting the HD 21749 Planetary System with Stellar Activity Modeling
• Solar Photospheric Spectrum Microvariability I. Theoretical searches for proxies of radial-velocity jittering