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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 358632.0, MPI für Astronomie / Publikationen_mpia
Detection of [Ne II] emission from young circumstellar disks
Authors: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.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Volume:663
Start Page:383
End Page:393
Audience:Not Specified
Abstract / Description:We report the detection of [Ne II] emission at 12.81 micron 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 micron from the source RXJ1852.3-3700. Detections of [Ne II] lines are favored by low mid-infrared excess emission. Both stellar X-rays and extreme UV (EUV) photons can sufficiently ionize the disk surface to reproduce the observed line fluxes, suggesting that emission from Ne+ 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 only for at most ~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 (~10^{-6} Jupiter masses) we suggest using this gas line to determine the presence or absence of gas in more evolved circumstellar disks.
Free Keywords:Astrophysics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2007astro.ph..3616P
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