True Masses using RV data with Hipparcos and Gaia Astrometry

TL;DR

This paper presents a combined model using Hipparcos, Gaia, and radial velocity data to accurately determine the true masses and orbital inclinations of long-period companions, revealing some are planets rather than brown dwarfs or stars.

Contribution

The work introduces a novel combined approach integrating astrometry and radial velocities to better constrain companion masses and inclinations, re-analyzing previously unstudied targets.

Findings

Some candidates are confirmed as planets.

HD 16760 b is a brown dwarf with a possible second companion.

HD 141937 b is likely a planet, but with uncertain mass.

Abstract

Long-period companions are detected and characterized thanks to long-baseline radial velocity surveys. Combining Doppler time-series with astrometry, and in particular with proper motion anomalies technique, it is possible to put strong constraints on their orbital inclination and true mass. This work aims to present a model that combines Hipparcos and Gaia astrometric data with radial velocity measurements to constrain the orbital inclinations and true masses of long-period companions. Additionally, we re-analyse a small sample of targets that have not yet been studied using this combined approach. This research leverages the simultaneous modelling of proper motion anomalies and radial velocities, in conjunction with an analysis of the sensitivity curve. This approach serves not only as a verification of the parameters but also as a means to acquire valuable insights into planetary systems. The new analyses reveal that some of the targets classified as brown dwarfs or small-mass stars have a planetary nature. HD 5388 b and HD 6718 b are likely planets. HD 141937 b is likely a planet, but the current dataset does not allow us to firmly constrain its true mass. HD 16760 b belongs to the brown dwarf regime and it has a probable second companion. 30 Ari B b falls within the stellar regime, but the presence of an additional stellar companion could compromise the reliability of the final results. For HD 148427 b, HD 96127 b and HIP 65891 b we determined a range for the orbital inclinations.