ALMA Observations of Asymmetric Molecular Gas Emission from a Protoplanetary Disk in the Orion Nebula

Journal Article · Mon May 01 04:00:00 EDT 2017 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AA6C2C· OSTI ID:22863086

Factor, Samuel M.; Hughes, A. M.; Flaherty, Kevin M. ^[1]; Mann, Rita K.; Francesco, James Di; Matthews, Brenda C.; Johnstone, Doug ^[2]; Williams, Jonathan P. ^[3]; Ricci, Luca ^[4]; Bally, John ^[5]

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1. Department of Astronomy, Van Vleck Observatory, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States)
2. National Research Council Canada Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada)
3. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
5. CASA, University of Colorado, CB 389, Boulder, CO 80309 (United States)

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of molecular line emission from d216-0939, one of the largest and most massive protoplanetary disks in the Orion Nebula Cluster. We model the spectrally resolved HCO{sup +} (4–3), CO (3–2), and HCN (4–3) lines observed at 0.′5 resolution to fit the temperature and density structure of the disk. We also weakly detect and spectrally resolve the CS (7–6) line but do not model it. The abundances we derive for CO and HCO{sup +} are generally consistent with expected values from chemical modeling of protoplanetary disks, while the HCN abundance is higher than expected. We dynamically measure the mass of the central star to be 2.17±0.07 M{sub ⊙}, which is inconsistent with the previously determined spectral type of K5. We also report the detection of a spatially unresolved high-velocity blueshifted excess emission feature with a measurable positional offset from the central star, consistent with a Keplerian orbit at 60 ± 20 au. Using the integrated flux of the feature in HCO{sup +} (4–3), we estimate the total H{sub 2} gas mass of this feature to be at least 1.8--8 M{sub Jupiter}, depending on the assumed temperature. The feature is due to a local temperature and/or density enhancement consistent with either a hydrodynamic vortex or the expected signature of the envelope of a forming protoplanet within the disk.

• OSTI ID: 22863086
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 5 Vol. 153; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
CARBON MONOXIDE
COMPUTERIZED SIMULATION
DENSITY
EMISSION
HYDROCYANIC ACID
HYDRODYNAMICS
HYDROGEN
MASS
NEBULAE
ORBITS
PLANETS
PROTOPLANETS
RESOLUTION
SATELLITES
STARS