The nearby young visual binary HIP 115147 and its common proper motion companion LSPM J2322+7847

TL;DR

This paper reports the discovery of a young, nearby low-mass star as a wide companion to a known binary, confirming its pre-main sequence status and estimating its age at 20-50 million years.

Contribution

It identifies and characterizes a new young low-mass star companion to a nearby binary, providing parallax, photometry, and age estimates, expanding knowledge of young stellar systems.

Findings

The companion has a parallax of 51.6 mas, consistent with the primary.

It is brighter than field M dwarfs at the same color, indicating pre-main sequence status.

Estimated age of the system is 20-50 Myr.

Abstract

We report a late M-type, common proper motion companion to a nearby young visual binary HIP 115147 (V368 Cep), separated by 963 arcseconds from the primary K0 dwarf. This optically dim star has been identified as a candidate high proper motion, nearby dwarf LSPM J2322+7847 by L{\'e}pine in 2005. The wide companion is one of the latest post-T Tauri low mass stars found within 20 pc. We obtain a trigonometric parallax of $51.6\pm0.8$ mas, in good agreement with the Hipparcos parallax of the primary star ($50.7\pm0.6$ mas). Our $BVRI$ photometric data and near-infrared data from 2MASS are consistent with LSPM J2322+7847 being brighter by 1 magnitude in $K_s$ than field M dwarfs at $V-K_s=6.66$, which indicates its pre-main sequence status. We conclude that the most likely age of the primary HIP 115147 and its 11-arcsecond companion HIP 115147B is 20-50 Myr. The primary appears to be older than its close analog PZ Tel (age 12-20 Myr) and members of the TWA association (7 Myr).