Identification of Bursting Water Maser Features in Orion KL

Abstract

In February 2011, a burst event of the H${}_2$O maser in Orion KL (Kleinmann-Low object) has started after 13-year silence. This is the third time to detect such phenomena in Orion KL, followed by those in 1979-1985 and 1998. We have carried out astrometric observations of the bursting H${}_2$O maser features in Orion KL with VERA (VLBI Exploration of Radio Astrometry), a Japanese VLBI network dedicated for astrometry. The total flux of the bursting feature at the LSR velocity of 7.58 km s${}^{-1}$ reaches 4.4$\times 10^4$ Jy in March 2011. The intensity of the bursting feature is three orders of magnitudes 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${}^{-1}$ in May 2011, separated by 12 mas north of the 7.58 km s${}^{-1}$ 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 submilli-arcsecond (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 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${}_2$O maser burst.

12 pages, 3 figures, accepted for publication in ApJL

References in corpus (5)

• Proplyds and Massive Disks in the Orion Nebula Cluster Imaged with CARMA and SMA
• A Multi-Epoch Study of the Radio Continuum Emission of Orion Source I: Constraints on the Disk Evolution of a Massive YSO and the Dynamical History of Orion BN/KL
• Orion KL: The hot core that is not a "Hot Core"
• High-Angular Resolution Dust Polarization Measurements: Shaped B-field Lines in the Massive Star Forming Region Orion BN/KL
• VERA 22 GHz fringe search survey

Cited by in corpus (12)

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• Hot Molecular Circumstellar Disk around Massive Protostar Orion Source I
• ALMA Imaging of Millimeter/Submillimeter Continuum Emission in Orion KL
• VERA and ALMA Observations of the H2O Supermaser Burst in Orion KL
• The first detection of the 232 GHz vibrationally excited H2O maser in Orion KL with ALMA
• ALMA observations of the archetypal "hot core" that isn't: Orion KL
• VLBI observations of the G25.65+1.05 water maser superburst
• Herschel/HIFI observations of a new interstellar water maser: the 5(32)-4(41) transition at 620.701 GHz
• ALMA Observation of the 658 GHz Vibrationally Excited H${}_2$O Maser in Orion KL Source I
• Evidence for dense gas heated by the explosion in Orion KL
• The Effelsberg survey of FU~Orionis and EX~Lupi objects II. -- H${}_2$O maser observations
• Polarisation Observations of H${}_2$O $J_{K_{-1}{K}_1}=5_{32}-4_{41}$ 620.701 GHz Maser Emission with Herschel/HIFI in Orion KL