Indirect Detection of Extrasolar Planets via Astrometry

TL;DR

This paper explores how radio astrometry, especially with ngVLA, can detect exoplanets in wide orbits around stars by measuring stellar reflex motion, complementing other detection methods.

Contribution

It demonstrates the potential of radio astrometry with ngVLA to identify exoplanets in wide orbits around stars using existing star catalogs.

Findings

ngVLA can detect planets in wide orbits around hundreds of stars

Astrometry is sensitive to face-on systems with large planets

Potential to identify planets around solar analogs

Abstract

Radio wavelength astrometry of stars and other objects has a long and productive history. The use of that technique to determine whether stars have planets around them would cover a nearly unique part of the parameter space for detection of those systems. Namely, astrometric observations are most sensitive to systems with large planets in moderately wide orbits (a few to ~10 AU), because it is those systems that produce large reflex motion of the star, in a short enough measurement period (years to tens of years). In addition, astrometric observations are most sensitive to systems which are nearly face-on. Other techniques (radial velocity, or the photometric method of Kepler) are more sensitive to systems with planets in close orbits (less than $\sim$1 AU), which are nearly edge-on. We describe here, using the Hipparcos and Gaia star catalogs, how ngVLA could use this technique on hundreds of stars, some tens of which are solar analogs, to determine whether these stars have planets orbiting them.