A young hierarchical triple system harbouring a candidate debris disc

TL;DR

This paper reports the discovery of a young hierarchical triple star system with a candidate debris disc around the primary star, which is rare for its age and offers insights into early stellar and planetary system evolution.

Contribution

It presents the identification and characterization of a unique young triple system with a debris disc, combining multi-wavelength observations and analysis to confirm its properties.

Findings

Primary star is a late-K with youth indicators.

Detection of a 100-175 K debris disc around the primary.

System is a rare example of a debris disc around a star older than 15 Myr.

Abstract

We report the detection of a wide young hierarchical triple system where the primary has a candidate debris disc. The primary, TYC 5241-986-1 A, is a known Tycho star which we classify as a late-K star with emission in the X-ray, near and far-UV and H\alpha\ suggestive of youth. Its proper motion, photometric distance (65-105 pc) and radial velocity lead us to associate the system with the broadly defined Local Association of young stars but not specifically with any young moving group. The presence of weak lithium absorption and X-ray and calcium H and K emission support an age in the 20 to ~125 Myr range. The secondary is a pair of M4.5+-0.5 dwarfs with near and far UV and H\alpha\ emission separated by approximately 1 arcsec (~65-105 AU projected separation) which lie 145 arcsec (9200-15200 AU) from the primary. The primary has a WISE 22 micron excess and follow-up Herschel observations also detect an excess at 70 micron. The excess emissions are indicative of a 100-175 K debris disc. We also explore the possibility that this excess could be due to a coincident background galaxy and conclude that this is unlikely. Debris discs are extremely rare around stars older than 15 Myr, hence if the excess is caused by a disc this is an extremely novel system.