Detection of [Ne II] emission from young circumstellar disks

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

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


We report the detection of [Ne II] emission at 12.81 μ 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 μm from the source RX J 1852.3-3700. 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+ 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 ∼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 MJ ) we suggest using this gas line to determine the presence or absence of gas in more evolved circumstellar disks.

Original languageEnglish (US)
Pages (from-to)383-393
Number of pages11
JournalAstrophysical Journal
Issue number1 I
StatePublished - Jul 1 2007


  • 3532, RX J1852.3
  • 3700)
  • 7620, RX J1842.9
  • Circumstellar matter
  • Infrared: stars
  • Line: identification
  • Planetary systems: protoplanetary disks
  • Stars: individual (HD 143006, PDS 66, [PZ99] J161411.0-230536, RX j1111.7

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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