Dynamical Measurements of the Young Upper Scorpius Triple NTTS 155808-2219

TL;DR

This study combines infrared and visible light spectroscopy over two decades to analyze the orbital dynamics of the young triple star system NTTS 155808-2219, providing insights into its mass distribution and potential eclipsing nature.

Contribution

The paper presents the first combined infrared and visible light radial velocity analysis of NTTS 155808-2219, refining orbital parameters and mass ratio estimates for this young triple system.

Findings

Mass ratio of the spectroscopic binary is q = 0.78 +/- 0.01.

Consistent orbital parameters derived from infrared and visible data.

Long-term radial velocity monitoring reveals acceleration of the binary's center-of-mass.

Abstract

The young, low-mass, triple system NTTS 155808-2219 (ScoPMS 20) was previously identified as a ~17-day period single-lined spectroscopic binary with a tertiary component at 0.21 arcseconds. Using high-resolution infrared spectra, acquired with NIRSPEC on Keck II, both with and without adaptive optics, we measured radial velocities of all three components. Reanalysis of the single-lined visible light observations, made from 1987 to 1993, also yielded radial velocity detections of the three stars. Combining visible light and infrared data to compute the orbital solution produces orbital parameters consistent with the single-lined solution and a mass ratio of q = 0.78 +/- 0.01 for the SB. We discuss the consistency between our results and previously published data on this system, our radial-velocity analysis with both observed and synthetic templates, and the possibility that this system is eclipsing, providing a potential method for the determination of the stars' absolute masses. Over the ~20 year baseline of our observations, we have measured the acceleration of the SB's center-of-mass in its orbit with the tertiary. Long-term, adaptive optics imaging of the tertiary will eventually yield dynamical data useful for component mass estimates.