ner_tags: O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength B-Citation I-Citation I-Citation I-Citation O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O B-Wavelength B-Wavelength O B-Wavelength I-Wavelength O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation O O O O O B-CelestialObject I-CelestialObject O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O B-Wavelength O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation O O O O O B-Wavelength I-Wavelength B-Tag O O O O O B-Observatory O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O B-CelestialObject I-CelestialObject O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O B-Observatory O O O O B-CelestialObjectRegion I-CelestialObjectRegion I-CelestialObjectRegion B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O B-CelestialObjectRegion I-CelestialObjectRegion I-CelestialObjectRegion O O B-Observatory O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O B-Wavelength O B-Wavelength I-Wavelength B-Citation I-Citation I-Citation I-Citation O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O B-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: ) and the 321 GHz H 2 O maser line (Hirota et al. 2014a ). The brightness temperature of the 658 GHz H 2 O line, >2 × 10 4 K, would indicate that the line is emitted via maser action. In contrast, the 336 GHz H 2 O line shows a different distribution (Figure 5 (c)) and a spectral profile with symmetric double-peaks (Figure 6 ). As discussed in Alcolea Menten ( 1993 ) and Hirota et al. ( 2014a ), the 336 GHz H 2 O line could be a thermal line and trace the edge-on disk, unlike emission from the other transitions at 232, 321, and 658 GHz. We note that via Menten et al. ( 2006 ) the 336 GHz H 2 O line toward the red supergiant VY CMa also favors a thermal nature for this line’s excitation. Recently, theoretical model calculations for the excitation of the 658 GHz H 2 O line have been presented (Richards et al. 2014 ; Nesterenok 2015 ) for the red supergiant VY CMa and for asymptotic giant branch (AGB) stars. The 658 GHz H 2 O maser is predicted to be pumped efficiently for H 2 densities of 10 9 –10 10 cm −3 , a fractional H 2 O abundance of 10 −4 –10 −5 , and gas temperatures of 1000–1500 K (Nesterenok 2015 ). Although the physical and chemical properties of the 658 GHz H 2 O maser emitting region associated with Source I would be expected to be different from that of a late-type star, these parameters are roughly consistent with those for the disk-outflow system of Source I associated with SiO masers and other submillimeter H 2 O lines (Reid et al. 2007 ; Goddi et al. 2009 , 2011 ; Hirota et al. 2014a , 2015 ). 4.4. Relationship between the 22 GHz H<sub>2</sub>O Supermaser We note that our ALMA observation was done during an active phase of the 22 GHz H 2 O maser burst in Orion KL, called a “supermaser” (Hirota et al. 2011 , 2014b ). The 22 GHz supermaser is located at the phase tracking center of the ALMA observation, corresponding to the Compact Ridge region (Hirota et al. 2011 , 2014b ). While the total flux density of the 22 GHz H 2 O supermaser was decreasing on 2012 August 25, it was still Jy (Hirota et al. 2014b ). In spite of the extremely high flux density of this maser, there was no significant emission of the 658 GHz H 2 O line in the Compact Ridge region in our ALMA data with the 1 σ noise level of 2 Jy beam −1 in the relevant region. Thus, the 658 GHz H 2 O line is not related to the 22 GHz supermaser phenomenon, as has also been reported for other transitions at 321 and 336 GHz (Hirota et al. 2014b ). 4.5. Continuum Emission at ALMA Band 9 To measure the position of the 658 GHz H 2 O emission, we also made a map of the ALMA band 9 continuum by applying the self-calibration solutions. Continuum emission is detected at the position of Source I, although it is outside the primary beam of the 12 m antenna. The flux density and the peak intensity are derived from Gaussian fitting, respectively 1.04 ± 0.04 Jy and 0.77 ± 0.03 Jy beam −1 (Figure 2 (b)). If we correct the primary beam attenuation by a factor of 8.6, the absolute flux