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E. L. N. Jensen, D. H. Cohen, V. Swisher (Swarthmore College), M. Gagné (West Chester University)
The weak-lined T Tauri star DoAr 21 has in the past shown a puzzling combination of observational traits: it has weak H-alpha emission and only a small near-infrared excess, yet it shows emission lines from molecular hydrogen and polycyclic aromatic hydrocarbons (PAHs). We present new Spitzer Space Telescope observations that show that DoAr 21 has a substantial infrared excess at 25 microns, indicating the presence of a substantial amount of cool outer disk material. New H-alpha observations show a weak but broad emission line, showing that some accretion is continuing onto the star. We discuss the role that the nearby B2 V star HD 147889 may play in exciting the PAH and molecular hydrogen emission from DoAr 21's disk. We also discuss the apparent spatial extent of the 25-micron emission in the Spitzer images. DoAr 21 may be in the process of clearing its disk from the inside out, with the outer disk being detectable partly due to the presence of a massive star nearby.
The authors gratefully acknowledge the support of the National Science Foundation through NSF grant AST-0307830.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.