Orbital Solutions for Two Young, Low-Mass Spectroscopic Binaries in Ophiuchus

TL;DR

This paper presents orbital parameters for two young, low-mass spectroscopic binaries in Ophiuchus, revealing a high eccentricity in one system and suggesting early orbital circularization within the first million years.

Contribution

It provides new orbital solutions for two pre-main sequence spectroscopic binaries, including the first detailed orbit with significant eccentricity for a short-period system.

Findings

RX J1622.7-2325Nw has an eccentricity of 0.30, higher than other similar binaries.

Orbital circularization likely occurs within the first 1 million years.

The study increases the known sample of PMS spectroscopic binaries by about 4%.

Abstract

We report the orbital parameters for ROXR1 14 and RX J1622.7-2325Nw, two young, low-mass, and double-lined spectroscopic binaries recently discovered in the Ophiuchus star forming region. Accurate orbital solutions were determined from over a dozen high-resolution spectra taken with the Keck II and Gemini South telescopes. These objects are T Tauri stars with mass ratios close to unity and periods of ~5 and ~3 days, respectively. In particular, RX J1622.7-2325Nw shows a non-circularized orbit with an eccentricity of 0.30, higher than any other short-period pre-main sequence spectroscopic binary known to date. We speculate that orbit of RX J1622.7-2325Nw has not yet circularized because of the perturbing action of a ~1" companion, itself a close visual pair. A comparison of known young spectroscopic binaries and main sequence (MS) spectroscopic binaries in the eccentricity-period plane shows an indistinguishable distribution of the two populations, implying that orbital circularization occurs in the first 1 Myr of a star's lifetime. With the results presented in this paper we are increasing by ~4% the small sample of PMS spectroscopic binary stars with known orbital elements.