MASS MEASUREMENTS IN PROTOPLANETARY DISKS FROM HYDROGEN DEUTERIDE

ABSTRACT The total gas mass of a protoplanetary disk is a fundamental, but poorly determined, quantity. A new technique has been demonstrated to assess directly the bulk molecular gas reservoir of molecular hydrogen using the HD J = 1-0 line at 112 m. In this work we present a Herschel Space Observa...

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Bibliographic Details
Published in:The Astrophysical journal 2016-11, Vol.831 (2), p.167
Main Authors: McClure, M. K., Bergin, E. A., Cleeves, L. I., Dishoeck, E. F. van, Blake, G. A., Evans II, N. J., Green, J. D., Henning, Th, Öberg, K. I., Pontoppidan, K. M., Salyk, C.
Format: Article
Language:English
Subjects:
astrobiology
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CARBON MONOXIDE
COSMIC DUST
COSMIC GASES
Depletion
Disks
EMISSION
ENERGY SPECTRA
Gas heating
HYDROGEN
HYDROGEN DEUTERIDE
MASS
Molecular gases
Organic chemistry
Planet formation
Protoplanetary disks
PROTOPLANETS
RADIANT HEAT TRANSFER
radiative transfer
SIMULATION
SPACE
Temperature structure
Vapor phases
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Summary:ABSTRACT The total gas mass of a protoplanetary disk is a fundamental, but poorly determined, quantity. A new technique has been demonstrated to assess directly the bulk molecular gas reservoir of molecular hydrogen using the HD J = 1-0 line at 112 m. In this work we present a Herschel Space Observatory10 survey of six additional T Tauri disks in the HD line. Line emission is detected at >3 significance in two cases: DM Tau and GM Aur. For the other four disks, we establish upper limits to the line flux. Using detailed disk structure and ray-tracing models, we calculate the temperature structure and dust mass from modeling the observed spectral energy distributions, and we include the effect of UV gas heating to determine the amount of gas required to fit the HD line. The ranges of gas masses are 1.0-4.7 × 10−2 for DM Tau and 2.5-20.4 × 10−2 for GM Aur. These values are larger than those found using CO for GM Aur, while the CO-derived gas mass for DM Tau is consistent with the lower end of our mass range. This suggests a CO chemical depletion from the gas phase of up to a factor of five for DM Tau and up to two orders of magnitude for GM Aur. We discuss how future analysis can narrow the mass ranges further.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/831/2/167