2006A&A...447.1011V


Query : 2006A&A...447.1011V

2006A&A...447.1011V - Astronomy and Astrophysics, volume 447, 1011-1025 (2006/3-1)

Water in the envelopes and disks around young high-mass stars.

VAN DER TAK F.F.S., WALMSLEY C.M., HERPIN F. and CECCARELLI C.

Abstract (from CDS):

Single-dish spectra and interferometric maps of (sub-) millimeter lines of H218O and HDO are used to study the chemistry of water in eight regions of high-mass star formation. The spectra indicate HDO excitation temperatures of ∼110K and column densities in an 11'' beam of ∼2x1014cm–2 for HDO and ∼2x1017cm–2 for H2O, with the N(HDO)/N(H2O) ratio increasing with decreasing temperature. Simultaneous observations of CH3OH and SO2 indicate that 20-50% of the single-dish line flux arises in the molecular outflows of these objects. The outflow contribution to the H218O and HDO emission is estimated to be 10-20%. Radiative transfer models indicate that the water abundance is low (∼10–6) outside a critical radius corresponding to a temperature in the protostellar envelope of ≃100K, and ``jumps'' to H2O/H2∼10–4 inside this radius. This value corresponds to the observed abundance of solid water and together with the derived HDO/H2O abundance ratios of ∼10–3 suggests that the origin of the observed water is evaporation of grain mantles. This idea is confirmed in the case of AFGL 2591 by interferometer observations of the HDO 110-111, H218O 313-220 and SO2 120,12-111,11 lines, which reveal compact (O∼800AU) emission with a systematic velocity gradient. This size is similar to that of the 1.3mm continuum towards AFGL 2591, from which we estimate a mass of ≃0.8M, or ∼5% of the mass of the central star. We speculate that we may be observing a circumstellar disk in an almost face-on orientation.

Abstract Copyright:

Journal keyword(s): ISM: molecules - molecular processes - stars: formation - astrochemistry

Simbad objects: 12

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Number of rows : 12
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 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 343 0
2 W 3(H2O) Mas 02 27 04.6 +61 52 25           ~ 137 0
3 RAFGL 490 Y*O 03 27 38.7928952784 +58 47 00.025298088           ~ 348 0
4 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1194 1
5 W 33a Y*O 18 14 39.56547 -17 52 02.2260           ~ 624 0
6 RAFGL 2136 Y*O 18 22 26.52888 -13 30 14.0400           ~ 277 0
7 NAME AFGL 2591 N2 Y*O 20 29 24.52 +40 11 20.1           ~ 20 1
8 NAME AFGL 2591 N1 Y*O 20 29 24.59 +40 11 15.0           ~ 22 1
9 RAFGL 2591 Y*O 20 29 24.8230 +40 11 19.590           ~ 606 0
10 NAME SH 2-140 IRS 1 Y*O 22 19 18.277 +63 18 45.82           ~ 195 0
11 [WBN74] NGC 7538 IRS 1 Y*O 23 13 45.318 +61 28 11.69           ~ 401 3
12 IRAS 23118+6110 Y*O 23 14 02.09473 +61 27 18.8460           ~ 368 0

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2023.02.04-10:48:50

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