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

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

2005-10-21

arxiv.org/abs/astro-ph/0510640v1

Astronomy and Astrophysics

Astrophysics

Accepted by A&A; 16 A4 pages; 12 colour figures

Scientific paper

10.1051/0004-6361:20053937

Single-dish spectra and interferometric maps of (sub)mm lines of H2O-18 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 ~110 K and column densities in an 11'' beam of ~2x10^14 cm^-2 for HDO and ~2x10^17 cm^-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 H2O-18 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 ~100 K, 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 ~1/1000 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 HDO, H2O-18 and SO2 lines, which reveal compact (~800 AU) emission with a systematic velocity gradient. This size is similar to that of the 1.3 mm continuum towards AFGL 2591, from which we estimate a mass of ~0.8 M0, 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.

Affiliated with

Also associated with

No associations

Rating

Water in the envelopes and disks around young high-mass stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Water in the envelopes and disks around young high-mass stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water in the envelopes and disks around young high-mass stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-88946