Signs of accretion in the white dwarf + brown dwarf binary NLTT5306

Abstract

We present new XSHOOTER spectra of NLTT5306, a 0.44 $\pm$ 0.04\msun white dwarf in a short period (101\,min) binary system with a brown dwarf companion that is likely to have previously undergone common envelope evolution. We have confirmed the presence of H$\alpha$ emission and discovered Na I absorption associated with the white dwarf. These observations are indicative of accretion. Accretion is typically evidenced by high energy emission in the UV and X-ray regime. However our \textit{Swift} observations covering the full orbital period in three wavebands (uvw1, uvm2, uvw2) revealed no UV excess or modulation. We used the X-ray non-detection to put an upper limit on the accretion rate of 2$\times$10${}^{-15}$\msun yr${}^{-1}$. We compare NLTT5306 to similar accreting binaries with brown dwarf donors and suggest the inferred accretion rate could be from wind accretion or accretion from a debris/dust disk. The lack of evidence for a disk implies NLTT5306 is magnetically funnelling a weak wind from a potentially low gravity brown dwarf. The upper limit on the accretion rate suggests a magnetic field as low as 0.45\,kG would be sufficient to achieve this. If confirmed this would constitute the first detection of a brown dwarf wind and could provide useful constraints on mass loss rates.

10 pages, 5 figures

References in corpus (32)

• An online repository of Swift/XRT light curves of GRBs
• A gaseous metal disk around a white dwarf
• Magnetic White Dwarfs
• Binary Star Origin of High Field Magnetic White Dwarfs
• Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation
• Survival of a brown dwarf after engulfment by a red giant star
• Rotational Modulation of the Radio Emission from the M9 Dwarf TVLM 513-46546: Broadband Coherent Emission at the Substellar Boundary?
• On the evolutionary status of short period cataclysmic variables
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• A brown dwarf mass donor in an accreting binary
• Evolution of Cataclysmic Variables and Related Binaries Containing a White-Dwarf
• Cataclysmic Variables from SDSS VII. The Seventh Year (2006)
• SDSS J150722.30+523039.8: a CV formed directly from a detached white dwarf/brown dwarf binary?
• Two white dwarfs in ultrashort binaries with detached, eclipsing, likely substellar companions detected by K2
• The substellar companion in the eclipsing white dwarf binary SDSS J141126.20+200911.1
• Dwarf nova-type cataclysmic variable stars are significant radio emitters
• Multiwaveband photometry of the irradiated brown dwarf WD0137-349B
• The nature of the close magnetic white dwarf + probable brown dwarf binary SDSS J121209.31+013627.7
• Magnetically gated accretion in an accreting 'non-magnetic' white dwarf
• Dynamical constraints on the component masses of the cataclysmic variable WZ Sge
• Quasi-Quiescent Radio Emission from the First Radio-Emitting T Dwarf
• Magnetism, X-rays, and Accretion Rates in WD 1145+017 and other Polluted White Dwarf Systems
• Emission lines in the atmosphere of the irradiated brown dwarf WD0137-349B
• The pre-cataclysmic variable, LTT560
• XMM-Newton observations of EF Eridani: the textbook example of low-accretion rate polars
• The Metallicity of Stars with Close Companions
• Orbital Parameters and Chemical Composition of Four White Dwarfs in Post-Common Envelope Binaries
• SDSS J105754.25+275947.5: a period-bounce eclipsing cataclysmic variable with the lowest-mass donor yet measured
• X-ray orbital modulation of a white dwarf accreting from an L dwarf: The system SDSS J121209.31+013627.7
• Orbital periods of cataclysmic variables identified by the SDSS. IX. NTT photometry of eight eclipsing and three magnetic systems
• Photometry of the Magnetic White Dwarf SDSS 121209.31+013627.7
• Brown Dwarf Companions to White Dwarfs

Cited by in corpus (16)

• Recurring Planetary Debris Transits and Circumstellar Gas around White Dwarf ZTF J0328$-$1219
• Close detached white dwarf + brown dwarf binaries: further evidence for low values of the common envelope efficiency
• WD1032+011, an inflated brown dwarf in an old eclipsing binary with a white dwarf
• Magnetic white dwarfs in post-common-envelope binaries
• Infrared Excesses around Bright White Dwarfs from Gaia and unWISE. II
• Spectroscopic and Photometric Periods of Six Ultracompact Accreting Binaries
• The Large Array Survey Telescope -- Science Goals
• Hot Subdwarf All Southern Sky Fast Transit Survey with the Evryscope
• Cataclysmic variables around the period-bounce: An eROSITA-enhanced multi-wavelength catalog
• Confirming new white dwarf-ultracool dwarf binary candidates
• Hard X-ray Emission Associated with White Dwarfs. IV. Signs of Accretion from Sub-stellar Companions
• Hotter Than Expected: HST/WFC3 Phase-resolved Spectroscopy of a Rare Irradiated Brown Dwarf with Strong Internal Heat Flux
• ZTFJ0038+2030: a long period eclipsing white dwarf and a substellar companion
• Measurement of stellar and substellar winds using white dwarf hosts
• Near-infrared spectra of the inflated post-common envelope brown dwarf NLTT 5306B
• Gaia white dwarfs with infrared excess I. The 100 pc catalogue