Imaging of Molecular Gas in Protoplanetary Disks on 1 AU Scales Using Spectro-astrometry
First Author:
Klaus Pontoppidan
Email: pontoppi AT gps.caltech.edu
Caltech, Department of Geological and Planetary Sciences
Mail Code 150-21
Pasadena, CA 91125 USA
Abstract
Spectro-astrometry is a technique that allows milli-arcsec spatial information to be extracted from emission lines in long-slit high resolution spectra. I will present results from a spectro-astrometric survey of the CO fundamental at 4.7 micron in low-mass protoplanetary disks, obtained using CRIRES - an AO-fed R=100,000 spectrometer on the European Very Large Telescope. The spectro-astrometry allows the measurement of geometric parameters of the molecular emission from the inner disks, such as position, inclination and spatial extent. These constraints are complementary to those obtained using current infrared interferometry. The survey reveals molecular gas in Keplerian motion, as well as gas with strong departures from Keplerian motion, suggestive of significant radial motions. The survey also includes a number of transitional protoplanetary disks and demonstrates that molecular gas is present even when small dust grains have been cleared from the inner disk. I will discuss possible interpretations of this. Finally, I will show that these observations demonstrate the feasibility of direct imaging of IR molecular line emission using the future generation of extremely large telescopes, provided that these are equipped with 3-12 micron R ~50-100,000 spectrometers.
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