Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf

February 2018 • 2018ApJ...854..145M

Authors • Mace, Gregory N. • Mann, Andrew W. • Skiff, Brian A. • Sneden, Christopher • Kirkpatrick, J. Davy • Schneider, Adam C. • Kidder, Benjamin • Gosnell, Natalie M. • Kim, Hwihyun • Mulligan, Brian W. • Prato, L. • Jaffe, Daniel

Abstract • Following the discovery of the T8 subdwarf WISE J200520.38+542433.9 (Wolf 1130C), which has a proper motion in common with a binary (Wolf 1130AB) consisting of an M subdwarf and a white dwarf, we set out to learn more about the old binary in the system. We find that the A and B components of Wolf 1130 are tidally locked, which is revealed by the coherence of more than a year of V-band photometry phase-folded to the derived orbital period of 0.4967 days. Forty new high-resolution, near-infrared spectra obtained with the Immersion Grating Infrared Spectrometer provide radial velocities and a projected rotational velocity (v sin i) of 14.7 ± 0.7 {km} {{{s}}}^-1 for the M subdwarf. In tandem with a Gaia parallax-derived radius and verified tidal locking, we calculate an inclination of i = 29° ± 2°. From the single-lined orbital solution and the inclination we derive an absolute mass for the unseen primary ({1.24}_-0.15^+0.19 M _⊙). Its non-detection between 0.2 and 2.5 μm implies that it is an old (>3.7 Gyr) and cool (T _eff < 7000 K) ONe white dwarf. This is the first ultramassive white dwarf within 25 pc. The evolution of Wolf 1130AB into a cataclysmic variable is inevitable, making it a potential SN Ia progenitor. The formation of a triple system with a primary mass >100 times the tertiary mass and the survival of the system through the common-envelope phase, where ∼80% of the system mass was lost, is remarkable. Our analysis of Wolf 1130 allows us to infer its formation and evolutionary history, which has unique implications for understanding low-mass star and brown dwarf formation around intermediate-mass stars.

Links

• PREPRINT http://arxiv.org/abs/1802.04803
• ELECTR https://doi.org/10.3847%2F1538-4357%2Faaa8dd
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2018ApJ...854..145M
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/aaa8dd/pdf
• PDF https://stacks.iop.org/0004-637X/854/145/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/854/145
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• DATA https://irsa.ipac.caltech.edu/bibdata/2018/M/2018ApJ...854..145M.html