Predictions of astrometric jitter for Sun-like stars. I. The model and its application to the Sun as seen from the ecliptic

Abstract

The advent of Gaia, capable of measuring stellar wobbles caused by orbiting planets, raised an interest to the astrometric detection of exoplanets. Another source of such wobbles (often also called jitter) is stellar magnetic activity. A quantitative assessment of the stellar astrometric jitter is important for a more reliable astrometric detection and characterisation of exoplanets. We calculate the displacement of the solar photocentre due to the magnetic activity for an almost 16-year period (February 2, 1999 - August 1, 2014). We also investigate how the displacement depends on the spectral passband chosen for observations, including the wavelength range to be covered by the upcoming Small-JASMINE mission of JAXA. This is done by extending the SATIRE-S model for solar irradiance variability to calculating the displacement of the solar photocentre caused by the magnetic features on the surface of the Sun. We found that the peak to peak amplitude of the solar photocentre displacement would reach 0.5 mas if the Sun were located 10 pc away from the observer and observed in the Gaia G filter. This is by far too small to be detected by the Gaia mission. However, the Sun is a relatively inactive star so that one can expect significantly larger signals for younger, and, consequently, more active stars. The model developed in this study can be combined with the simulations of emergence and surface transport of magnetic flux which have recently became available to model the astrometric jitter over the broad range of magnetic activities.

Accepted for publication in ApJ

References in corpus (19)

• The Gaia mission
• Astrometric exoplanet detection with Gaia
• The solar magnetic field
• Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI and SDO/HMI observations
• Magnitudes and Timescales of Total Solar Irradiance Variability
• The Sun is less active than other solar-like stars
• The variability of Sun-like stars: reproducing observed photometric trends
• The influence of metallicity on stellar differential rotation and magnetic activity
• UV solar irradiance in observations and the NRLSSI and SATIRE-S models
• A new SATIRE-S spectral solar irradiance reconstruction for solar cycles 21--23 and its implications for stratospheric ozone
• Limits of ultra-high-precision optical astrometry: Stellar surface structures
• Inflection point in the power spectrum of stellar brightness variations. I. The model
• Activity time series of old stars from late F to early K. I. Simulating radial velocity, astrometry, photometry, and chromospheric emission
• Power spectra of solar brightness variations at different inclinations
• Amplification of brightness variability by active-region nesting in solar-like stars
• Solar-type Stars Observed by LAMOST and Kepler
• Astrometric effects of solar-like magnetic activity in late-type stars and their relevance for the detection of extrasolar planets
• Connecting measurements of solar and stellar brightness variations
• Astrometric Detection of exo-Earths in the Presence of Stellar Noise

Cited by in corpus (7)

• Predictions of Astrometric Jitter for Sun-like Stars. II. Dependence on Inclination, Metallicity, and Active-Region Nesting
• Closeby Habitable Exoplanet Survey (CHES). I. Astrometric Noise and Planetary Detection Efficiency due to Stellar Spots and Faculae
• Predictions of Astrometric Jitter for Sun-like Stars. III. Fast Rotators
• Multiwavelength Mitigation of Stellar Activity in Astrometric Planet Detection
• Inferring hemispheric asymmetries of stellar active regions through the information content of astrometric signals
• A Dataset for Exploring Stellar Activity in Astrometric Measurements from SDO Images of the Sun
• Astrometric exoplanet detection survives solar-like stellar contamination