A J-band detection of the sub-stellar mass donor in SDSS J1433+1011

Abstract

We present time-resolved J-band spectroscopy of the short period cataclysmic variable SDSS J143317.78+101123.3. We detect absorption lines from the sub-stellar donor star in this system, which contributes 38 ± 5 % to the J-band light. From the relative strengths of the absorption lines in the J-band, we estimate the spectral type of the donor star to be L2 ± 1. These data are the first spectroscopic detection of a confirmed sub-stellar donor in a cataclysmic variable, and the spectral type is consistent with that expected from semi-empirical evolutionary models.Using skew mapping, we have been able to derive an estimate for the radial velocity of the donor of K d = 520 ± 60 km s −1 . This value is consistent with, though much less precise than, predictions from mass determinations found via photometric fitting of the eclipse light curves.

An irradiated brown-dwarf companion to an accreting white dwarf

“…This donor spectrum was then compared to an empirical brown dwarf spectral sequence 11 . The best-matching spectral type was found to be SpT=L1±1, which agrees remarkably well with semi-empirical evolutionary predictions 1, 2 and with previous narrow J-band estimates 3 .…”

“…In fact, the internal and external energy fluxes are both expected to be comparable in these objects, providing access to an unexplored irradiation regime. However, the atmospheric properties of such donors have so far remained largely unknown 3 . Here, we report the direct spectroscopic detection and characterisation of an irradiated sub-stellar donor in an accreting white dwarf binary system.…”

“…Only a single brown dwarf donor to an accreting white dwarf has been detected spectroscopically to date 3 , and no empirical information at all is available regarding the effect of irradiation on the donor's atmosphere. We have therefore carried out simultaneous optical and nearinfrared time-resolved spectroscopy of one such system with the X-Shooter instrument 6 at the Very Large Telescope (ESO).…”

X-ray orbital modulation of a white dwarf accreting from an L dwarf

“…To date, only four period-bounce candidates have infrared detections: EF Eri (Schwope et al 2007), SDSS J 143317.78+ 101123.3 (Littlefair et al 2013;Hernández Santisteban et al 2016), WZ Sge (Harrison 2016), and SDSS 1212 (Farihi et al 2008). SDSS J 1433+1011 and WZ Sge are non-magnetic CVs, while EF Eri has been the textbook example for a LARP, but is also considered a candidate period bouncer (Schwope et al 2007;Schwope & Christensen 2010).…”

pt5m– a 0.5 m robotic telescope on La Palma

“…It functions as an astrophysics research facility, an atmospheric turbulence profiler, and a teaching resource. pt5m has already been used to study pulsating stars, transiting exoplanets, Solar system objects, interacting binaries (Littlefair et al 2013;Kupfer et al 2014;Campbell et al 2015), and transients (Gandhi et al 2014;Hardy et al 2015), but no detailed description of pt5m itself has appeared in the E-mail: vik.dhillon@sheffield.ac.uk 1 For a global list of robotic telescopes, see http://www.astro. physik.uni-goettingen.de/∼hessman/MONET/links.html 2 The name is an abbreviated form of 'point-five-metre '. refereed astronomical literature to date.…”