X-ray Detections of Two Young Bona-Fide Brown Dwarfs

Abstract

I report here the detection of two bona-fide brown dwarfs by XMM-Newton: [GY92] 141 in the rho-Ophiuchus star forming region and DENIS-P J155601-233809 in the Upper Scorpius OB association. The two objects have been detected with luminosities of Lx=8.35\pm2.86*10^28 erg/s and Lx=6.54\pm1.35*10^28 erg/s respectively, corresponding to luminosity ratios of log(Lx/Lbol)= -2.07 and log(Lx/Lbol)= -2.69. The two sources were close to the limit of detection of the instruments at only 2~3-sigma above the background level, and no significant flare or variation could be detected during the 48.3ks and 33.9ks observations. [GY92] 141 had already been observed 10 months earlier with Chandra (see 2001 ApJ, 563, 361) with a luminosity ~14 times fainter than the one I report here, meaning that the X-ray emission of this object is strongly variable.

9 pages, 3 figures, accepted for A&A

References in corpus (4)

• Evidence for a T Tauri Phase in Young Brown Dwarfs
• Gravity Indicators in the Near-Infrared Spectra of Brown Dwarfs
• A Systematic Study of X-Ray Flares from Low-Mass Young Stellar Objects in the Rho Ophiuchi Star-Forming Region with Chandra
• Coronal X-ray emission from an intermediate-age brown dwarf

Cited by in corpus (6)

• Spectroscopic rotational velocities of brown dwarfs
• X-ray emission of brown dwarfs: Towards constraining the dependence on age, luminosity, and temperature
• Quiescent X-ray emission from an evolved brown dwarf ?
• New deep XMM-Newton observations to the west of the sigma Orionis cluster
• Observations of Ultracool dwarfs with ULTRACAM on the VLT: a search for weather
• XMM-Newton survey of two Upper Scorpius regions