THE FIRST DETECTION OF THE 232 GHz VIBRATIONALLY EXCITED H{sub 2}O MASER IN ORION KL WITH ALMA

Journal Article · Thu Sep 20 04:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/757/1/L1· OSTI ID:22078545

Hirota, Tomoya; Kim, Mi Kyoung; Honma, Mareki ^[1]

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1. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

We investigated the ALMA science verification data of Orion KL and found a spectral signature of the vibrationally excited H{sub 2}O maser line at 232.68670 GHz ({nu}{sub 2} = 1, 5{sub 5,0}-6{sub 4,3}). This line has been detected previously in circumstellar envelopes of late-type stars but not in young stellar objects such as Orion KL. Thus, this is the first detection of the 232 GHz vibrationally excited H{sub 2}O maser in star-forming regions. The distribution of the 232 GHz maser is concentrated at the position of the radio Source I, which is remarkably different from other molecular lines. The spectrum shows a double-peak structure at the peak velocities of -2.1 and 13.3 km s{sup -1}. It appears to be consistent with the 22 GHz H{sub 2}O masers and 43 GHz SiO masers observed around Source I. Thus, the 232 GHz H{sub 2}O maser around Source I would be excited by the internal heating by an embedded protostar, being associated with either the root of the outflows/jets or the circumstellar disk around Source I, as traced by the 22 GHz H{sub 2}O masers or 43 GHz SiO masers, respectively.

• OSTI ID: 22078545
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 757; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DETECTION
GHZ RANGE
HEATING
MASERS
PROTOSTARS
SILICON OXIDES
SPECTRA
STARS
VIBRATIONAL STATES
WATER