An irradiated brown-dwarf companion to an accreting white dwarf

Abstract

Brown dwarfs and giant planets orbiting close to a host star are subjected to significant irradiation that can modify the properties of their atmospheres. In order to test the atmospheric models that are used to describe these systems, it is necessary to obtain accurate observational estimates of their physical properties (masses, radii, temperatures, albedos). Interacting compact binary systems provide a natural laboratory for studying strongly irradiated sub-stellar objects. As the mass-losing secondary in these systems makes a critical, but poorly understood transition from the stellar to the sub-stellar regime, it is also strongly irradiated by the compact accretor. 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. Here, we report the direct spectroscopic detection and characterisation of an irradiated sub-stellar donor in an accreting white dwarf binary system. Our near-infrared observations allow us to determine a model-independent mass estimate for the donor of $M_2=0.055\pm 0.008M_{\odot }$ and an average spectral type of $L1\pm 1$, supporting both theoretical predictions and model-dependent observational constraints. Our time-resolved data also allow us to estimate the average irradiation-induced temperature difference between the day and night sides on the sub-stellar donor, $\Delta \mathrm{T}\simeq 57$~K, and the maximum difference between the hottest and coolest parts of its surface, of $\Delta {\mathrm{T}}_{max}\simeq 200$~K. The observations are well described by a simple geometric reprocessing model with a bolometric (Bond) albedo of $A_B<0.54$ at 2-$\sigma$ confidence level, consistent with high reprocessing efficiency, but poor lateral heat redistribution in the donor's atmosphere.

arXiv comment19 pages, 4 figures, published in Nature 19 May

References in corpus (22)

• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• An Infrared Spectroscopic Sequence of M, L and T Dwarfs
• The Evolution of Cataclysmic Variables as Revealed by their Donor Stars
• The Statistics of Albedo and Heat Recirculation on Hot Exoplanets
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• The Donor Stars of Cataclysmic Variables
• SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period
• Post-common-envelope binaries from SDSS. XI: The white dwarf mass distributions of CVs and pre-CVs
• Atmospheric Heat Redistribution on Hot Jupiters
• On the Orbits of Low-mass Companions to White Dwarfs and the Fates of the Known Exoplanets
• Atmospheric dynamics of brown dwarfs and directly imaged giant planets
• On the evolutionary status of short period cataclysmic variables
• KOI 1224, a Fourth Bloated Hot White Dwarf Companion Found With Kepler
• Thermal Structure and Radius Evolution of Irradiated Gas Giant Planets
• A brown dwarf mass donor in an accreting binary
• Cataclysmic Variables below the Period Gap: Mass Determinations of 14 Eclipsing Systems
• The Formation of Cataclysmic Variables with Brown Dwarf Secondaries
• Model Atmospheres for Irradiated Stars in pre-Cataclysmic Variables
• The cataclysmic variable SDSS J1507+52: An eclipsing period bouncer in the Galactic halo
• Radial-velocity study of the post-period minimum cataclysmic variable SDSSJ143317.78+101123.3 with an electron-multiplying CCD
• A J-band detection of the sub-stellar mass donor in SDSS J1433+1011
• Not Alone: Tracing the Origins of Very Low Mass Stars and Brown Dwarfs Through Multiplicity Studies

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