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

McAllister, MJ and Littlefair, SP and Baraffe, I and Dhillon, VS and Marsh, TR and Bento, J and Bochinski, J and Bours, MCP and Breedt, E and Copperwheat, CM and Hardy, LK and Kerry, P and Parsons, SG and Rostron, JW and Sahman, DI and 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: 09 Sep 2015 13:16
DOI or Identification number: 10.1093/mnras/stv956
URI: http://researchonline.ljmu.ac.uk/id/eprint/1021

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