Details

Autor(en) / Beteiligte

• Pascucci, I
• Hollenbach, D
• Najita, J
• Muzerolle, J
• Gorti, U
• Herczeg, G. J
• Hillenbrand, L. A
• Kim, J. S
• Carpenter, J. M
• Meyer, M. R
• Mamajek, E. E
• Bouwman, J

Titel

Detection of [Ne II] Emission from Young Circumstellar Disks

Ist Teil von

• The Astrophysical journal, 2007-07, Vol.663 (1), p.383-395

Ort / Verlag

Chicago, IL: IOP Publishing

Erscheinungsjahr

2007

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• We report the detection of [Ne II] emission at 12.81 mu m in four out of the six optically thick dust disks observed as part of the FEPS Spitzer Legacy program. In addition, we detect a H I (7-6) emission line at 12.37 mu m from the source RX J1852.3-3700. Detections of [Ne II] lines are favored by low mid-Infrared excess emission. Both stellar X-rays and extreme ultraviolet (EUV) photons can sufficiently ionize the disk surface to reproduce the observed line fluxes, suggesting that emission from Ne super(+) originates in the hot disk atmosphere. On the other hand, the H I (7-6) line is not associated with the gas in the disk surface, and magnetospheric accretion flows can account for at most similar to 30% of the observed flux. We conclude that accretion shock regions and/or the stellar corona could contribute to most of the H I (7-6) emission. Finally, we discuss the observations necessary to identify whether stellar X-rays or EUV photons are the dominant ionization mechanism for Ne atoms. Because the observed [Ne II] emission probes very small amounts of gas in the disk surface ( similar to 10 super(-6) MJ) we suggest using this gas line to determine the presence or absence of gas in more evolved circumstellar disks.