Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-06-08
Astrophys.J. 627 (2005) L149-L152
Astronomy and Astrophysics
Astrophysics
13 pages, 1 Figure, ApJ Letters, in press
Scientific paper
10.1086/432468
Recent analysis of high resolution Chandra X-ray spectra has shown that the Ne/O abundance ratio is remarkably constant in stellar coronae. Based on this result, we point out the utility of the Ne/O ratio as a discriminant for accretion-related X-rays from T Tauri stars, and for probing the measure of grain-depletion of the accreting material in the inner disk. We apply the Ne/O diagnostic to the classical T Tauri stars BP Tau and TW Hya--the two stars found to date whose X-ray emission appears to originate, at least in part, from accretion activity. We show that TW Hya appears to be accreting material which is significantly depleted in O relative to Ne. In constrast, BP Tau has an Ne/O abundance ratio consistent with that observed for post-T Tauri stars. We interpret this result in terms of the different ages and evolutionary states of the circumstellar disks of these stars. In the young BP Tau disk (age 0.6 Myr) dust is still present near the disk corotation radius and can be ionized and accreted, re-releasing elements depleted onto grains. In the more evolved TW Hya disk (age 10 Myr), evidence points to ongoing coagulation of grains into much larger bodies, and possibly planets, that can resist the drag of inward-migrating gas, and accreting gas is consequently depleted of grain-forming elements.
No associations
LandOfFree
X-ray Diagnostics of Grain Depletion in Matter Accreting onto T Tauri Stars 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 X-ray Diagnostics of Grain Depletion in Matter Accreting onto T Tauri Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray Diagnostics of Grain Depletion in Matter Accreting onto T Tauri Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-171000