Dynamical mass of the Serpens intermediate-mass young stellar system EC\,95 with DYNAMO--VLBA

TL;DR

This study measures the dynamical masses of the EC 95 young stellar system in Serpens using VLBI over 12 years, revealing it as a hierarchical triple system with detailed mass estimates for each component.

Contribution

First dynamical mass measurements of EC 95's components using multi-epoch VLBI data, confirming its hierarchical triple structure and estimating the mass of the third, low-mass component.

Findings

Mass of EC 95A: 2.15 ± 0.10 M☉

Mass of EC 95B: 2.00 ± 0.12 M☉

Mass of EC 95C: 0.26 (+0.53, -0.46) M☉

Abstract

We present dynamical mass measurements, obtained from multi-epoch Very Long Baseline Interferometry (VLBI) observations, for the young multiple stellar system EC\,95, located in the core of the Serpens star-forming region. Our dataset includes both archival data and more recent observations obtained as part of the \textit{Dynamical Masses of Young Stellar Multiple Systems with the VLBA project} (DYNAMO--VLBA), totalling 32 epochs over 12 years of observation. The observations span more than half of the EC\,95AB orbit, which has an estimated period of $21.6\pm0.1$ years, and yield masses of $2.15\pm0.10$ M$_\odot$ for EC\,95A and $2.00\pm0.12$ M$_\odot$ for EC\,95B. Furthermore, for the first time, we have estimated the mass of the third component (EC\,95C) using four available radio detections as well as an infrared observation. We find it to be 0.26 $^{+0.53}_{-0.46}$ M$_\odot$, suggesting that E\,95C is a low-mass T Tauri star. We conclude that EC\,95 is a hierarchical triple system comprised of a tight central binary proto-Herbig\,AeBe system and a lower mass companion on a wider orbit. These results contribute to improve our understanding of the stellar dynamics in this system and provide valuable insights into its triple nature.