Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-09-13
Astrophys.J. 578 (2002) L141-L144
Astronomy and Astrophysics
Astrophysics
to appear in The Astrophysical Journal Letters
Scientific paper
10.1086/344707
We present high-resolution optical spectra of 15 objects near or below the sub-stellar limit in the Upper Scorpius and $\rho$ Ophiuchus star-forming regions. These spectra, obtained with the HIRES instrument on the Keck I telescope, are used to investigate disk accretion, rotation and activity in young very low mass objects. We report the detection of a broad, asymmetric H$\alpha$ emission line in the $\rho$ Oph source GY 5 which is also known to harbor mid-infrared excess, consistent with the presence of an accreting disk. The H$\alpha$ profiles of the Upper Sco objects suggest little or no on-going accretion. Our results imply that if most brown dwarfs are born with disks, their accretion rates decrease rapidly, at timescales comparable to or smaller than those for T Tauri disks. The Upper Sco brown dwarfs appear to be rotating faster than their somewhat younger counterparts in Taurus, consistent with spin-up due to contraction following disk unlocking. The H$\alpha$ activity is comparable to saturated activity levels in field M dwarfs with similar spectral type and rotation rates. Comparison of our data with published (albeit lower-resolution) spectra of a few of the same objects from other epochs suggests possible variability in accretion/activity indicators.
Basri Gibor
Jayawardhana Ray
Mohanty Subhanjoy
No associations
LandOfFree
Probing Disk Accretion in Young Brown Dwarfs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Probing Disk Accretion in Young Brown Dwarfs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probing Disk Accretion in Young Brown Dwarfs will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-356163