Back to Volume
Paper: Dynamical Mass Determination of Pre-MS Binaries: A Case Study and Future Prospects of Near-Infrared Interferometry
Volume: 318, Spectroscopically and Spatially Resolving the Components of Close Binary Stars
Page: 34
Authors: Zinnecker, H.; Correia, S.
Abstract: The masses and ages of young low-mass stars are very uncertain, perhaps by a factor of ∼1.5 — 2. This is due to their pre-Main Sequence (PMS) contraction, where the stellar luminosity and color not only depend on mass (as during hydrogen burning) but also on age. In this situation, it is very difficult to derive the stellar mass distribution and the star formation history in a young cluster or association from photometry. The way to overcome the problem is to calibrate and test PMS evolutionary tracks by resolving the astrometric orbits of young double-lined spectroscopic binaries (SB2) and by placing the binary components on the HR-diagram. We illustrate the procedure to derive component masses of young binaries, describing a case study (NTTS 045251+3016, P=7 yr) where we could resolve the pair and follow the orbit for several years using HST/FGS observations. This has allowed us to derive both the dynamical masses and the orbital parallax of a PMS star for the first time. With the imminent advent of near-infrared long-baseline interferometry (particularly VLTI) the future of this research field is very bright, and we plan to survey short-period (P<1 yr) spectroscopic binaries in nearby star forming regions with the aim to resolve their close components. At a typical distance of 150 pc (Taurus, Sco- Cen) 1AU corresponds to 7 mas, easily within reach of ESO's VLTI (AMBER) at 1 — 2 microns. Such observations hold great promise to improve the mass determinations of young low-mass stars to <10% accuracy.
Back to Volume