2004/01/27 by L. van Zyl, P. A. Charles, S. Arribas +4 · 1 citation
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #High-pressure geophysics and materials #Mechanics and Biomechanics Studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07676.x
published as Mon.Not.Roy.Astron.Soc. 350 (2004) 649 · 8 pages, 6 figures, accepted for publication in MNRAS
arxiv created 2004/01/27 · openalex publication_date 2004/04/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present integral field spectroscopy of X2127+119, the luminous X-ray binary in the globular cluster M15, obtained with INTEGRAL/WYFFOS on the William Herschel Telescope. We find that tomograms of He iiλ4686 line profiles appear to be incompatible with the previously assumed view of X2127+119, in which the binary consists of a 1.4-M⊙ neutron star and a 0.8-M⊙ subgiant companion near the main-sequence turn-off for M15. Our data imply a much smaller mass ratio M2/MX of ∼0.1. We find that models of X2127+119 with black hole compact objects give a poor fit to our data, while a neutron-star compact object is consistent with the data, implying that the companion of X2127+119 may have a much lower mass (∼0.1 M⊙) than previously assumed. As a ∼0.1-M⊙ main-sequence star would be unable to fill its Roche lobe in a binary with the orbital period of X2127+119 (17.1 h), the companion is likely to be the remnant of a significantly more massive star which has had most of its envelope stripped away.