# The curious case of PDS 11: a nearby, >10 Myr old, classical T Tauri binary system

## TL;DR

This study characterizes the PDS 11 binary system, a rare, isolated, high-latitude T Tauri pair aged 10-15 million years, both actively accreting, with one component showing lithium indicative of youth.

## Contribution

We provide detailed spectroscopic analysis and age estimation of PDS 11, identifying it as a rare old, dusty, wide binary classical T Tauri system with both components actively accreting.

## Key findings

- PDS 11 is a M2-M2 binary with similar H-alpha emission.
- PDS 11A shows lithium, indicating youth, while PDS 11B does not.
- Estimated age of PDS 11A is 10-15 Myr.

## Abstract

We present results of our study of PDS 11 binary system, which belongs to a rare class of isolated, high galactic latitude T Tauri stars. Our spectroscopic analysis reveals that PDS 11 is a M2-M2 binary system with both components showing similar H-alpha emission strength. Both the components appear to be accreting, and are classical T Tauri stars. The lithium doublet Li I 6708 Angstrom, a signature of youth, is present in the spectrum of PDS 11A, but not in PDS 11B. From the application of lithium depletion boundary age-dating method and a comparison with the Li I 6708 equivalent width distribution of moving groups, we estimated an age of 10-15 Myr for PDS 11A. Comparison with pre-main sequence evolutionary models indicates that PDS 11A is a 0.4 solar mass T Tauri star at a distance of 114-131 pc. PDS 11 system does not appear to be associated with any known star forming regions or moving groups. PDS 11 is a new addition, after TWA 30 and LDS 5606, to the interesting class of old, dusty, wide binary classical T Tauri systems in which both components are actively accreting.