The Quest for the Sun's Siblings: an Exploratory Search in the Hipparcos Catalogue

TL;DR

This study searches for the Sun's sibling stars in the Hipparcos Catalogue using orbital simulations, finding only one potential candidate and discussing future prospects with Gaia data.

Contribution

It introduces a method combining orbital simulations and stellar data to identify potential Sun siblings, and evaluates its effectiveness with current data.

Findings

Only one candidate star remains after analysis.

The search results align with previous predictions about sibling scarcity.

Future Gaia data could improve search success.

Abstract

We describe the results of a search for the remnants of the Sun's birth cluster among stars in the Hipparcos Catalogue. This search is based on the predicted phase space distribution of the Sun's siblings from simple simulations of the orbits of the cluster stars in a smooth Galactic potential. For stars within 100 pc the simulations show that it is interesting to examine those that have small space motions relative to the Sun. From amongst the candidate siblings thus selected there are six stars with ages consistent with that of the Sun. Considering their radial velocities and abundances only one potential candidate, HIP 21158, remains but essentially the result of the search is negative. This is consistent with predictions by Portegies Zwart (2009) on the number of siblings near the Sun. We discuss the steps that should be taken in anticipation of the data from the Gaia mission in order to conduct fruitful searches for the Sun's siblings in the future.