Water depletion in the disk atmosphere of Herbig AeBe stars

D. Fedele, I. Pascucci, S. Brittain, I. Kamp, P. Woitke, J. P. Williams, W. R.F. Dent, W. F. Thi

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39 Scopus citations

Abstract

We present high-resolution (R ∼ 100,000) L-band spectroscopy of 11 Herbig AeBe stars with circumstellar disks. The observations were obtained with the VLT/CRIRES to detect hot water and hydroxyl radical emission lines previously detected in disks around T Tauri stars. OH emission lines are detected toward four disks. The OH 2Π3/2 P4.5 (1+,1-) doublet is spectrally resolved as well as the velocity profile of each component of the doublet. Its characteristic double-peak profile demonstrates that the gas is in Keplerian rotation and points to an emitting region extending out to ∼15-30AU. The OH emission correlates with disk geometry as it is mostly detected toward flaring disks. None of the Herbig stars analyzed here show evidence of hot water vapor at a sensitivity similar to that of the OH lines. The non-detection of hot water vapor emission indicates that the atmospheres of disks around Herbig AeBe stars are depleted of water molecules. Assuming LTE and optically thin emission we derive a lower limit to the OH/H2O column density ratio >1-25 in contrast to T Tauri disks for which the column density ratio is 0.3-0.4.

Original languageEnglish (US)
Article number106
JournalAstrophysical Journal
Volume732
Issue number2
DOIs
StatePublished - May 10 2011

Keywords

  • astrochemistry
  • molecular processes
  • protoplanetary disks
  • stars: pre-main sequence
  • stars: variables: T Tauri, Herbig Ae/Be

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Fedele, D., Pascucci, I., Brittain, S., Kamp, I., Woitke, P., Williams, J. P., Dent, W. R. F., & Thi, W. F. (2011). Water depletion in the disk atmosphere of Herbig AeBe stars. Astrophysical Journal, 732(2), [106]. https://doi.org/10.1088/0004-637X/732/2/106