First Ultraviolet Spectrum of a Brown Dwarf: Evidence for H_2 Fluorescence and Accretion

Abstract

We analyze an HST/STIS ultraviolet spectrum of the young brown dwarf 2MASSW J1207334-393254, a member of the ten million-year old TW Hya Association that has a planetary-mass companion. We detect and identify numerous emission lines. CIV and other ions are seen that arise in hot gas. We identify a series of lines with Lyman-pumped H_2 molecular lines, indicating that cool gas is also present. Overall, this substellar object shows many of the same characteristics as classical T Tauri stars. We interpret our results as direct evidence of accretion from a circumstellar gas disk, consistent with previous claims. The lack of SiIV emission from the accreting gas indicates that silicon has been depleted into grains.

arXiv comment8 pages, to appear in Astrophysical Journal Letters

References in corpus (17)

• A Giant Planet Candidate near a Young Brown Dwarf
• The T Tauri Phase Down to Nearly Planetary Masses: Echelle Spectra of 82 Very Low Mass Stars and Brown Dwarfs
• Brown Dwarfs and the TW Hya Association
• The FUV spectrum of TW Hya. I. Observations of H${}_2$ Fluorescence
• Hubble Space Telescope Observations of Binary Very-Low-Mass Stars and Brown Dwarfs
• The Far-Ultraviolet Spectra of TW Hya. II. Models of H2 Fluorescence in a Disk
• A Disk Census for Young Brown Dwarfs
• Infrared Views of the TW Hya Disk
• Magellan Echelle Spectroscopy of TW Hydrae Brown Dwarfs
• A Survey for Circumstellar Disks Around Young Substellar Objects
• Evolution of Young Brown Dwarf Disks in the Mid-Infrared
• A disk census for the nearest group of young stars: Mid-infrared observations of the TW Hydrae Association
• Spitzer Identification of the Least Massive Known Brown Dwarf with a Circumstellar Disk
• Flared Disks and Silicate Emission in Young Brown Dwarfs
• Mid-infrared imaging of the young binary star Hen 3-600: Evidence for a dust disk around the primary
• Transition Region Emission From Very Low Mass Stars
• A Chandra Observation of a TW Hydrae Association Brown Dwarf

Cited by in corpus (15)

• The Planetary Mass Companion 2MASS1207-3932 B: Temperature, Mass and Evidence for an Edge-On Disk
• The Origins of Fluorescent H2 Emission From T Tauri~Stars
• Atmospheres of Brown Dwarfs
• Very Low-Mass Objects in the Coronet Cluster: The Realm of the Transition Disks
• Discovery of a High Proper Motion L Dwarf Binary: 2MASS J15200224-4422419AB
• Emission Line Variability of the Accreting Young Brown Dwarf 2MASSW J1207334-393254: From Hours to Years
• The Trigonometric Parallax of the Brown Dwarf Planetary System 2MASSW J1207334-393254
• HD 100453: A Link Between Gas-Rich Protoplanetary Disks and Gas-Poor Debris Disks
• Characterizing the disk around the TW Hydrae Association brown dwarf 2MASSW J1207334-393254
• Metal Depletion and Warm H2 in the Brown Dwarf 2M1207 Accretion Disk
• JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B
• Spitzer Observations of two TW Hydrae Association Brown Dwarfs
• Observational diagnostics of gas in protoplanetary disks
• Discovery of Lyman-alpha Pumped Molecular Hydrogen Emission in the Planetary Nebulae NGC 6853 and NGC 3132
• A U-band survey of brown dwarfs in the Taurus Molecular Cloud with the XMM-Newton Optical/UV Monitor