Program: GS-2006A-C-10
Title: | Phoenix Observations of CH4, HCN and CO in the Planet Formation Zone |
PI: | Adwin Boogert |
Co-I(s): | Geoff Blake, Ken Hinkle |
Abstract
The structure and composition of envelopes and disks surrounding
protostars are key factors in planet and comet formation. The region
at 1-10s of AU is of particular interest, but often highly obscured in
young systems and therefore not accessible at optical
wavelengths. High resolution infrared spectroscopy provides a powerful
probe of the gas and dust close to young stars, however. Indeed, in
our large 4.7 um CO survey of protostars line widths of several 10s of
km/s have been observed both in emission and absorption. These
velocities tie the gas to the inner few AU of the disk/envelope. We
propose to follow up on this survey and observe the fundamental C-H
stretching bands of HCN at 3.1 um and CH4 at 3.3 um using the R=60,000
(5 km/s) mode of Phoenix at Gemini-South. As gas and dust travel
toward the protostar, CH4 will first sublimate from icy grain mantles
and is expected to 'burn' rapidly into CO. However, at high pressures
and moderate temperatures CO can be converted back into CH4, and the
CH4/CO abundance ratio may thus be a unique tracer of protoplanetary
condensations within disks. On the other hand, HCN is a tracer of
high temperature `hot core'-type chemistry in the very inner regions
of protostellar disks. At high spectral resolution provided by
Phoenix, the line profiles will localize the absorbing/emitting
regions, and thus the disk composition in the potential planet
formation zone.
Publications using this program's data
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[data]
[ADS] Molecular Gas in the Inner 1 AU of the TW Hya and GM Aur Transitional Disks
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[data]
[ADS] High-resolution 5 μm Spectroscopy of Transitional Disks
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[data]
[ADS] CO Rovibrational Emission as a Probe of Inner Disk Structure