2010A&A...521L..26L


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.14CEST02:39:58

2010A&A...521L..26L - Astronomy and Astrophysics, volume 521, L26-26 (2010/10-1)

Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C.

LIS D.C., PHILLIPS T.G., GOLDSMITH P.F., NEUFELD D.A., HERBST E., COMITO C., SCHILKE P., MUELLER H.S.P., BERGIN E.A., GERIN M., BELL T.A., EMPRECHTINGER M., BLACK J.H., BLAKE G.A., BOULANGER F., CAUX E., CECCARELLI C., CERNICHARO J., COUTENS A., CROCKETT N.R., DANIEL F., DARTOIS E., DE LUCA M., DUBERNET M.-L., ENCRENAZ P., FALGARONE E., GEBALLE T.R., GODARD B., GIESEN T.F., GOICOECHEA J.R., GRY C., GUPTA H., HENNEBELLE P., HILY-BLANT P., KOLOS R., KRELOWSKI J., JOBLIN C., JOHNSTONE D., KAZMIERCZAK M., LORD S.D., MARET S., MARTIN P.G., MARTIN-PINTADO J., MELNICK G.J., MENTEN K.M., MONJE R., MOOKERJEA B., MORRIS P., MURPHY J.A., OSSENKOPF V., PEARSON J.C., PERAULT M., PERSSON C., PLUME R., QIN S.-L., SALEZ M., SCHLEMMER S., SCHMIDT M., SONNENTRUCKER P., STUTZKI J., TEYSSIER D., TRAPPE N., VAN DER TAK F.F.S., VASTEL C., WANG S., YORKE H.W., YU S., ZMUIDZINAS J., BOOGERT A., ERICKSON N., KARPOV A., KOOI J., MAIWALD F.W., SCHIEDER R. and ZAAL P.

Abstract (from CDS):

We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H216O and H218O in absorption towards Sagittarius B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of 2.35±0.35, corresponding to a spin temperature of ∼27K, towards Sagittarius B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.

Abstract Copyright:

Journal keyword(s): astrochemistry - ISM: abundances - ISM: molecules - molecular processes - submillimeter: ISM

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11620 0
2 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1921 1
3 NAME Sgr B2 (South) HII 17 47 20.430 -28 23 45.06           ~ 85 0
4 NAME Sgr B2 Main Rad 17 47 20.5 -28 23 06           ~ 333 1
5 W 31c HII 18 10 29.1 -19 56 05           ~ 301 0
6 NAME Sgr Arm PoG 19 00 -30.0           ~ 524 1
7 NAME Scutum Spiral Arm PoG ~ ~           ~ 275 0
8 NAME Ori Arm PoG ~ ~           ~ 178 0

    Equat.    Gal    SGal    Ecl

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2020.08.14-02:39:59

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