Water deuterium fractionation in the low-mass protostar NGC1333-IRAS2A

• Published in: Astronomy and astrophysics (Berlin) 2011-03, Vol.527, p.A19
• Main Authors: Liu, F.-C., Parise, B., Kristensen, L., Visser, R., van Dishoeck, E. F., Güsten, R.
• Format: Article
• Language: English
• Subjects: astrochemistry; Astronomy; Earth, ocean, space; Exact sciences and technology; ISM: individual objects: NGC1333-IRAS2A; ISM: molecules; stars: formation; stars: solar-type
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201015519

Context. Although deuterium enrichment of water may provide an essential piece of information in the understanding of the formation of comets and protoplanetary systems, only a few studies up to now have aimed at deriving the HDO/H2O ratio in low-mass star forming regions. Previous studies of the molecular deuteration toward the solar-type class 0 protostar, IRAS 16293-2422, have shown that the D/H ratio of water is significantly lower than other grain-surface-formed molecules. It is not clear if this property is general or particular to this source. Aims. In order to see if the results toward IRAS 16293−2422 are particular, we aimed at studying water deuterium fractionation in a second low-mass solar-type protostar, NGC1333-IRAS2A. Methods. Using the 1-D radiative transfer code RATRAN, we analyzed five HDO transitions observed with the IRAM 30 m, JCMT, and APEX telescopes. We assumed that the abundance profile of HDO in the envelope is a step function, with two different values in the inner warm (T > 100 K) and outer cold (T