No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21

Details No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21 No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21

2009-07-28

arxiv.org/abs/0907.4980v1

Astrophysical Journal 703 (2009) 252-269.

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

Accepted by ApJ; 50 pages, 15 figures

Scientific paper

10.1088/0004-637X/703/1/252

We present new high-resolution mid-infrared imaging, high-resolution optical spectroscopy, and Chandra grating X-ray spectroscopy of the weak-lined T Tauri star DoAr 21. DoAr 21 (age < 10^6 yr and mass ~ 2.2 M_sun) is a strong X-ray emitter, with conflicting evidence in the literature about its disk properties. It shows weak but broad H-alpha emission; polarimetric variability; PAH and H2 emission; and a strong, spatially-resolved 24-micron excess in archival Spitzer photometry. Gemini sub-arcsecond-resolution 9--18 micron images show that there is little or no excess mid-infrared emission within 100 AU of the star; the excess emission is extended over several arcseconds, is quite asymmetric, and is bright in the UV-excited 11.3 micron PAH emission feature. A new high-resolution X-ray grating spectrum from Chandra shows that the stellar X-ray emission is very hard and dominated by continuum emission; it is well-fit by a multi-temperature thermal model and shows no evidence of unusually high densities. We argue that the far-ultraviolet emission from the star's transition region is sufficient to excite the observed extended PAH and continuum emission, and that the H2 emission may be similarly extended and excited. This extended emission may be more akin to a small-scale photodissociation region than a protoplanetary disk, highlighting both the very young ages (< 10^6 yr) at which some stars are found without disks, and the extreme radiation environment around even late-type pre--main-sequence stars.

Affiliated with

Also associated with

No associations

Rating

No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21 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 No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and No Transition Disk? Infrared Excess, PAH, H2, and X-rays from the Weak-Lined T Tauri Star DoAr 21 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-520837