Evidence for CO depletion in the inner regions of gas-rich protoplanetary disks
Abstract
Aims: We investigate the physical properties and spatial distribution of Carbon Monoxide (CO) gas in the disks around the Herbig Ae/Be stars HD 97048 and HD 100546.
Methods: Using high-spectral-resolution 4.588-4.715 μm spectra containing fundamental CO emission taken with CRIRES on the VLT, we probe the circumstellar gas and model the kinematics of the emission lines. By using spectro-astrometry on the spatially resolved targets, we constrain the physical size of the emitting regions in the disks.
Results: We resolve, spectrally and spatially, the emission of the 13CO v(1-0) vibrational band and the 12CO v = 1-0, v = 2-1, v = 3-2 and v = 4-3 vibrational bands in both targets, as well as the 12CO v = 5-4 band in HD 100546. Modeling of the CO emission with a homogeneous disk in Keplerian motion, yields a best fit with an inner and outer radius of the CO emitting region of 11 and ≥100 AU for HD 97048. HD 100546 is not fit well with our model, but we derive a lower limit on the inner radius of 8 AU. The fact that gaseous [OI] emission was previously detected in both targets at significantly smaller radii suggests that CO may be effectively destroyed at small radii in the surface layers of these disks.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2009
- DOI:
- 10.1051/0004-6361/200811148
- arXiv:
- arXiv:0810.3417
- Bibcode:
- 2009A&A...500.1137V
- Keywords:
-
- circumstellar matter;
- stars: pre-main sequence;
- stars: individual: HD 97048;
- stars: individual: HD 100546;
- planetary systems: protoplanetary disks;
- Astrophysics
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