2008A&A...477..185M


Query : 2008A&A...477..185M

2008A&A...477..185M - Astronomy and Astrophysics, volume 477, 185-192 (2008/1-1)

A multi-transition submillimeter water maser study of evolved stars. Detection of a new line near 475 GHz.

MENTEN K.M., LUNDGREN A., BELLOCHE A., THORWIRTH S. and REID M.J.

Abstract (from CDS):

Maser emission from the H2O molecule probes the warm, inner circumstellar envelopes of oxygen-rich red giant and supergiant stars. Multi-maser transition studies can be used to put constraints on the density and temperature of the emission regions. A number of known H2O maser lines were observed toward the long period variables R Leo and W Hya and the red supergiant VY CMa. A search for a new, not yet detected line near 475GHz was conducted toward these stars. The Atacama Pathfinder Experiment telescope was used for a multi-transition observational study of submillimeter H2O lines. The 533-440 transition near 475 GHz was clearly detected toward VY CMa and W Hya. Many other H2O lines were detected toward all three target stars. Relative line intensity ratios and velocity widths were found to vary significantly from star to star. Maser action is observed in all but one line for which it was theoretically predicted. In contrast, one of the strongest maser lines, in R Leo by far the strongest, the 437GHz 753-660 transition, is not predicted to be inverted. Some other qualitative predictions of the model calculations are at variance with our observations. Plausible reasons for this are discussed. Based on our findings for W Hya and VY CMa, we find evidence that the H2O masers in the AGB star W Hya arise from the regular circumstellar outflow, while shock excitation in a high velocity flow seems to be required to excite masers far from the red supergiant VY CMa.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: winds, outflows - supergiants - circumstellar matter - masers - submillimeter

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* VY CMa s*r 07 22 58.3261352189 -25 46 03.194390594 12.01 10.068 8.691 7.938   M5Iae 1072 0
2 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 895 1
3 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2276 0
4 V* W Hya Mi* 13 49 02.0018313132 -28 22 03.532006894   8.97 7.70     M7.5-9e 628 0

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2023.02.08-01:19:55

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