Astronomy and Astrophysics, volume 529, L7-7 (2011/5-1)
Deuteration as an evolutionary tracer in massive-star formation.
FONTANI F., PALAU A., CASELLI P., SANCHEZ-MONGE A., BUTLER M.J., TAN J.C., JIMENEZ-SERRA I., BUSQUET G., LEURINI S. and AUDARD M.
Abstract (from CDS):
Theory predicts, and observations confirm, that the column density ratio of a molecule containing D to its counterpart containing H can be used as an evolutionary tracer in the low-mass star formation process. Since it remains unclear if the high-mass star formation process is a scaled-up version of the low-mass one, we investigated whether the relation between deuteration and evolution can be applied to the high-mass regime. With the IRAM-30m telescope, we observed rotational transitions of N2D+ and N2H+ and derived the deuterated fraction in 27 cores within massive star-forming regions understood to represent different evolutionary stages of the massive-star formation process. The abundance of N2D+ is higher at the pre-stellar/cluster stage, then drops during the formation of the protostellar object(s) as in the low-mass regime, remaining relatively constant during the ultra-compact HII region phase. The objects with the highest fractional abundance of N2D+ are starless cores with properties very similar to typical pre-stellar cores of lower mass. The abundance of N2D+ is lower in objects with higher gas temperatures as in the low-mass case but does not seem to depend on gas turbulence. Our results indicate that the N2D+-to-N2H+ column density ratio can be used as an evolutionary indicator in both low- and high-mass star formation, and that the physical conditions influencing the abundance of deuterated species likely evolve similarly during the processes that lead to the formation of both low- and high-mass stars.
stars: formation - ISM: clouds - ISM: molecules - radio lines: ISM
Table A.1: [FPC2011] I22134-A (Nos B, G), [FPC2011] I22134-VLA1 N=1.
+ corrigendum vol. 562, p. C1 (2014)
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