Water depletion in the disk atmosphere of Herbig Ae/Be stars

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

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44 Citations (Scopus)

Abstract

We present high-resolution (R similar to 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 (2)Pi(3/2) 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 similar to 15-30 AU. 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
Article number106
Pages (from-to)-
Number of pages12
JournalAstrophysical Journal
Volume732
Issue number2
DOIs
Publication statusPublished - 10 May 2011

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