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PHL 1445: An eclipsing cataclysmic variable with a substellar donor near the period minimum

McAllister, MJ, Littlefair, SP, Baraffe, I, Dhillon, VS, Marsh, TR, Bento, J, Bochinski, J, Bours, MCP, Breedt, E, Copperwheat, CM, Hardy, LK, Kerry, P, Parsons, SG, Rostron, JW, Sahman, DI, Savoury, CDJ and Tunnicliffe, RL (2015) PHL 1445: An eclipsing cataclysmic variable with a substellar donor near the period minimum. Monthly Notices of the Royal Astronomical Society, 451 (1). pp. 114-125. ISSN 1365-2966

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We present high-speed, three-colour photometry of the eclipsing dwarf nova PHL 1445, which, with an orbital period of 76.3 min, lies just below the period minimum of ~82 min for cataclysmic variable stars. Averaging four eclipses reveals resolved eclipses of the white dwarf and bright spot. We determined the system parameters by fitting a parameterised eclipse model to the averaged lightcurve. We obtain a mass ratio of q = 0.087 +- 0.006 and inclination i = 85.2 +- 0.9 degrees. The primary and donor masses were found to be Mw = 0.73 +- 0.03 Msun and Md = 0.064 +- 0.005 Msun, respectively. Through multicolour photometry a temperature of the white dwarf of Tw = 13200 +- 700 K and a distance of 220 +- 50 pc were determined. The evolutionary state of PHL 1445 is uncertain. We are able to rule out a significantly evolved donor, but not one that is slightly evolved. Formation with a brown dwarf donor is plausible; though the brown dwarf would need to be no older than 600 Myrs at the start of mass transfer, requiring an extremely low mass ratio (q = 0.025) progenitor system. PHL 1445 joins SDSS 1433 as a sub-period minimum CV with a substellar donor. These existence of two such systems raises an alternative possibility; that current estimates for the intrinsic scatter and/or position of the period minimum may be in error.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (July 21, 2015) 451 (1): 114-125 is available online at: http://dx.doi.org/10.1093/mnras/stv956
Uncontrolled Keywords: astro-ph.SR; astro-ph.SR
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 07 May 2015 13:59
Last Modified: 04 Sep 2021 14:26
DOI or ID number: 10.1093/mnras/stv956
URI: https://researchonline.ljmu.ac.uk/id/eprint/1021
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