IDENTIFICATION OF BURSTING WATER MASER FEATURES IN ORION KL
- National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510 (Japan)
- Faculty of Science, Yamaguchi University, Yamaguchi, Yamaguchi 753-8512 (Japan)
- Department of Astronomical Sciences, Graduate University for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588 (Japan)
- Graduate School of Science and Engineering, Kagoshima University, Kagoshima, Kagoshima 890-0065 (Japan)
- Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan)
- Center for Astronomy, Ibaraki University, Mito, Ibaraki 310-8512 (Japan)
In 2011 February, a burst event of the H{sub 2}O maser in Orion KL (Kleinmann-Low object) has started after a 13 year silence. This is the third time such phenomena has been detected in Orion KL, followed by the events in 1979-1985 and 1998. We have carried out astrometric observations of the bursting H{sub 2}O maser features in Orion KL with the VLBI Exploration of Radio Astrometry (VERA), a Japanese very long baseline interferometry network dedicated for astrometry. The total flux of the bursting feature at the local standard of rest (LSR) velocity of 7.58 km s{sup -1} reaches 4.4 x 10{sup 4} Jy in 2011 March. The intensity of the bursting feature is three orders of magnitude larger than that of the same velocity feature in the quiescent phase in 2006. Two months later, another new feature appears at the LSR velocity of 6.95 km s{sup -1} in 2011 May, separated by 12 mas north of the 7.58 km s{sup -1} feature. Thus, the current burst occurs at two spatially different features. The bursting masers are elongated along the northwest-southeast direction as reported in the previous burst in 1998. We determine the absolute positions of the bursting features for the first time ever with a submilliarcsecond (mas) accuracy. Their positions are coincident with the shocked molecular gas called the Orion Compact Ridge. We tentatively detect the absolute proper motions of the bursting features toward the southwest direction. It is most likely that the outflow from the radio source I or another young stellar object interacting with the Compact Ridge is a possible origin of the H{sub 2}O maser burst.
- OSTI ID:
- 21565419
- Journal Information:
- Astrophysical Journal Letters, Vol. 739, Issue 2; Other Information: DOI: 10.1088/2041-8205/739/2/L59; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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