| Parise, Berengere, Caux, E., Castets, A., Ceccarelli, C., Loinard, L., Tielens, A. G. G. M., Bacmann, A., Cazaux, S., Comito, C., Helmich, F., Kahane, C., Schilke, P., van Dishoeck, E., Wakelam, V. and Walters, A. 2005. HDO abundance in the envelope of the solar-type protostar IRAS 16293-2422. Astronomy and Astrophysics 431 (2) , pp. 547-554. 10.1051/0004-6361:20041899 |
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Abstract
We present IRAM 30 m and JCMT observations of HDO lines towards the solar-type protostar IRAS 16293-2422. Five HDO transitions have been detected on-source, and two were unfruitfully searched for towards a bright spot of the outflow of IRAS 16293-2422. We interpret the data by means of the Ceccarelli et al. (1996) model, and derive the HDO abundance in the warm inner and cold outer parts of the envelope. The emission is well explained by a jump model, with an inner abundance $x{^{\tiny\rm {HDO}}_{\rm in}} = 1\times10^{-7}$ and an outer abundance $x{^{\tiny\rm {HDO}}_{\rm out}}\,\leq\,1\times10^{-9}$ (3 $\sigma$). This result is in favor of HDO enhancement due to ice evaporation from the grains in the inner envelope. The deuteration ratio HDO/H 2O is found to be $f_{\rm in}=3\%$ and $f_{\rm out} \le 0.2\%$ (3 $\sigma$) in the inner and outer envelope respectively and therefore, the fractionation also undergoes a jump in the inner part of the envelope. These results are consistent with the formation of water in the gas phase during the cold prestellar core phase and storage of the molecules on the grains, but do not explain why observations of H 2O ices consistently derive a H 2O ice abundance of several 10 -5 to 10 -4, some two orders of magnitude larger than the gas phase abundance of water in the hot core around IRAS 16293-2422.
| Item Type: | Article |
|---|---|
| Status: | Published |
| Schools: | Schools > Physics and Astronomy |
| Subjects: | Q Science > QB Astronomy |
| Uncontrolled Keywords: | ISM: molecules; stars: formation; stars: individual: IRAS 16293-2422 |
| Additional Information: | Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-6361/ (accessed 17/04/2014) |
| Publisher: | EDP Sciences |
| ISSN: | 0004-6361 |
| Date of First Compliant Deposit: | 30 March 2016 |
| Last Modified: | 17 May 2023 00:47 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/52823 |
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