Astrometric Detection of exo-Earths in the Presence of Stellar Noise

TL;DR

This paper demonstrates that space astrometry can detect Earth-like exoplanets around Sun-like stars despite stellar noise, which significantly hampers radial velocity methods, highlighting astrometry's robustness for habitable planet detection.

Contribution

It shows that astrometric detection of Earth-mass planets is feasible despite starspot noise, unlike radial velocity methods which are more affected.

Findings

Astrometry can detect sub-Earth mass planets in the habitable zone.

Starspot noise severely impacts radial velocity detection.

Astrometric detectability remains robust against stellar noise.

Abstract

Space astrometry is capable of sub-microarcsecond measurements of star positions. A hundred visits over several years could yield relative astrometric precision of ~0.1 uas, below the astrometric signature (0.3 uas) of a Sun-Earth system at a distance of 10 parsecs. We investigate the impact of starspots on the detectability, via astrometric and radial velocity techniques, of Earthlike planets orbiting Sunlike stars. We find that for nearby stars, although starspot noise imposes severe restrictions on detectability by the radial velocity technique, it does not significantly affect astrometric detectability of habitable zone planets down to below an Earth mass.