2006/08/04 by Amanda J. Bayless, Jerome A. Orosz · 3 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Eclipse #Epoch (astronomy) #Light curve #Observatory #Photometry (optics) #Physics #Radial velocity #Stars #Stellar, planetary, and galactic studies #Telescope #astro-ph
paper · pdf · doi:10.1086/507981
published as Astrophys.J.651:1155-1165,2006 · 16 pages, 10 figures (Figure 1 has degraded quality), to appear in ApJ
arxiv created 2006/08/04 · openalex publication_date 2006/11/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We show that the star known as 2MASS J05162881+2607387 (hereafter J0516) is a double-lined eclipsing binary with nearly identical low-mass components. The spectroscopic elements derived from 18 spectra obtained with the High Resolution Spectrograph on the Hobby-Eberly Telescope during the fall of 2005 are K 1 = 88.45 ± 0.48 and K 2 = 90.43 ± 0.60 km s -1 , resulting in a mass ratio of q = K 1 / K 2 = 0.978 ± 0.018 and minimum masses of M 1 i = 0.775 ± 0.016 M ☉ and M 2 i = 0.759 ± 0.012 M ☉ , respectively. We have extensive differential photometry of J0516 obtained over several nights between 2004 January and March (epoch 1) and between 2004 October and 2005 January plus 2006 January (epoch 2) using the 1 m telescope at the Mount Laguna Observatory. The source was roughly 0.1 mag brighter in all three bandpasses during epoch 1 when compared to epoch 2. Also, phased light curves from epoch 1 show considerable out-of-eclipse variability, presumably due to bright spots on one or both stars. In contrast, the phased light curves from epoch 2 show little out-of-eclipse variability. The light curves from epoch 2 and the radial velocity curves were analyzed using our ELC code with updated model atmospheres for low-mass stars. We find the following: M 1 = 0.787 ± 0.012 M ☉ , R 1 = 0.788 ± 0.015 R ☉ , M 2 = 0.770 ± 0.009 M ☉ , and R 2 = 0.817 ± 0.010 R ☉ . The stars in J0516 have radii that are significantly larger than model predictions for their masses, similar to what is seen in a handful of other well-studied low-mass double-lined eclipsing binaries. We compiled all recent mass and radius determinations from low-mass binaries and determine an empirical mass-radius relation of the form R ( R ☉ ) = 0.0324 + 0.9343 M ( M ☉ ) + 0.0374 M 2 ( M ☉ ).