Predictions of Astrometric Jitter for Sun-like Stars. III. Fast Rotators

Abstract

A breakthrough in exoplanet detections is foreseen with the unprecedented astrometric measurement capabilities offered by instrumentation aboard Gaia space observatory. Besides, astrometric discoveries of exoplanets are expected from the planned space mission, Small-JASMINE. In this setting, the present series of papers focuses on estimating the effect of magnetic activity of G2V-type host stars on the astrometric signal. This effect interferes with the astrometric detections of Earth-mass planets. While the first two papers considered stars rotating at the solar rotation rate, this paper focuses on stars having solar effective temperature and metallicity but rotating faster than the Sun, and consequently more active. By simulating the distribution of active regions on such stars using the Flux Emergence And Transport model, we show that the contribution of magnetic activity to the astrometric measurements becomes increasingly significant with increasing rotation rates. We further show that the jitter for the most variable periodic Kepler stars is high enough to be detected by Gaia. Furthermore, due to a decrease in the facula-to-spot area ratio for more active stars, the magnetic jitter is found to be spot-dominated for rapid rotators. Our simulations of the astrometric jitter has the potential to aid the interpretation of data from Gaia and upcoming space astrometry missions.

21 pages, 20 figures, accepted for publication in ApJ

References in corpus (11)

• The Gaia mission
• Astrometric exoplanet detection with Gaia
• The Sun is less active than other solar-like stars
• The variability of Sun-like stars: reproducing observed photometric trends
• Powering Stellar Magnetism: Energy Transfers in Cyclic Dynamos of Sun-like Stars
• Modelling total solar irradiance since 1878 from simulated magnetograms
• Predictions of Astrometric Jitter for Sun-like Stars. II. Dependence on Inclination, Metallicity, and Active-Region Nesting
• A new estimation of astrometric exoplanet detection limits in the habitable zone around nearby stars
• Predictions of astrometric jitter for Sun-like stars. I. The model and its application to the Sun as seen from the ecliptic
• Multiwavelength Mitigation of Stellar Activity in Astrometric Planet Detection
• Exploring the solar paradigm to explain stellar variability

Cited by in corpus (5)

• Closeby Habitable Exoplanet Survey (CHES). I. Astrometric Noise and Planetary Detection Efficiency due to Stellar Spots and Faculae
• Forward modelling of brightness variations in Sun-like stars -- II. Light curves and variability
• Low-latitude magnetic flux emergence on rapidly rotating solar-type stars
• A Dataset for Exploring Stellar Activity in Astrometric Measurements from SDO Images of the Sun
• Astrometric exoplanet detection survives solar-like stellar contamination