Emission lines in the atmosphere of the irradiated brown dwarf WD0137-349B

Abstract

We present new optical and near-infrared spectra of WD0137-349; a close white dwarf - brown dwarf non-interacting binary system with a period of $\approx$114 minutes. We have confirmed the presence of H$\alpha$ emission and discovered He, Na, Mg, Si, K, Ca, Ti, and Fe emission lines originating from the brown dwarf atmosphere. This is the first brown dwarf atmosphere to have been observed to exhibit metal emission lines as a direct result of intense irradiation. The equivalent widths of many of these lines show a significant difference between the day and night sides of the brown dwarf. This is likely an indication that efficient heat redistribution may not be happening on this object, in agreement with models of hot Jupiter atmospheres. The H$\alpha$ line strength variation shows a strong phase dependency as does the width. We have simulated the Ca II emission lines using a model that includes the brown dwarf Roche geometry and limb darkening and we estimate the mass ratio of the system to be 0.135$\pm$0.004. We also apply a gas-phase equilibrium code using a prescribed drift-phoenix model to examine how the chemical composition of the brown dwarf upper atmosphere would change given an outward temperature increase, and discuss the possibility that this would induce a chromosphere above the brown dwarf atmosphere.

10 pages, 7 figures, 2 tables

References in corpus (13)

• Survival of a brown dwarf after engulfment by a red giant star
• Debris Disks Around White Dwarfs: The DAZ Connection
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• Atmospheres of Brown Dwarfs
• 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
• 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
• The pre-cataclysmic variable, LTT560
• The Metallicity of Stars with Close Companions
• A new L5 brown dwarf member of the Hyades cluster with chromospheric activity
• Brown Dwarf Companions to White Dwarfs

Cited by in corpus (19)

• Atmospheric Dynamics of Hot Giant Planets and Brown Dwarfs
• Atmospheric Regimes and Trends on Exoplanets and Brown Dwarfs
• Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere
• 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
• Five New Post-Main-Sequence Debris Disks with Gaseous Emission
• WD1032+011, an inflated brown dwarf in an old eclipsing binary with a white dwarf
• Simplified 3D GCM modelling of the irradiated brown dwarf WD0137-349B
• NLTT5306B: an inflated, weakly irradiated brown dwarf
• Signs of accretion in the white dwarf + brown dwarf binary NLTT5306
• Lightning and charge processes in brown dwarf and exoplanet atmospheres
• Atmosphere Models of Brown Dwarfs Irradiated by White Dwarfs: Analogues for Hot and Ultra-Hot Jupiters
• Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b: III. Changing ionisation and the emergence of an ionosphere
• HST/WFC3 Complete Phase-resolved Spectroscopy of White Dwarf-Brown Dwarf Binaries WD 0137 and EPIC 2122
• Mapping the pressure-dependent day-night temperature contrast of a strongly irradiated atmosphere with HST spectroscopic phase curve
• Confirming new white dwarf-ultracool dwarf binary candidates
• Lightning in other planets
• Measurement of stellar and substellar winds using white dwarf hosts
• An irradiated-Jupiter analogue hotter than the Sun