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arXiv · 1802.04803

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

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

Following the discovery of the T8 subdwarf WISEJ200520.38+542433.9 (Wolf 1130C), with common proper motion to 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 (IGRINS) provide radial velocities and a projected rotational velocity (v sin i) of 14.7 +/- 0.7 km/s for the M subdwarf. In tandem with a Gaia parallax-derived radius and verified tidal-locking, we calculate an inclination of i=29 +/- 2 degrees. From the single-lined orbital solution and the inclination we derive an absolute mass for the unseen primary (1.24+0.19-0.15 Msun). Its non-detection between 0.2 and 2.5 microns implies that it is an old (>3.7 Gyr) and cool (Teff<7000K) ONe white dwarf. This is the first ultramassive white dwarf within 25pc. The evolution of Wolf 1130AB into a cataclysmic variable is inevitable, making it a potential Type Ia supernova 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.

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Gregory N. Mace, Andrew W. Mann, Brian A. Skiff, Christopher Sneden, Davy Kirkpatrick, Adam C. Schneider, Benjamin Kidder, Natalie M. Gosnell, Hwihyun Kim, Brian W. Mulligan, L. Prato, Daniel Jaffe. 2018-02-13. Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf. https://doi.org/10.3847/1538-4357/aaa8dd

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