Query : 2008A&A...482..535H

2008A&A...482..535H - Astronomy and Astrophysics, volume 482, 535-539 (2008/5-1)

Detection of 6 K gas in Ophiuchus D.


Abstract (from CDS):

Cold cores in interstellar molecular clouds represent the very first phase in star formation. The physical conditions of these objects are studied in order to understand how molecular clouds evolve and how stellar masses are determined. The purpose of this study is to probe conditions in the dense, starless clump Ophichus D (Oph D). The ground-state (110->111) rotational transition of ortho-H2D+ was observed with APEX towards the density peak of Oph D. The width of the H2D+ line indicates that the kinetic temperature in the core is about 6K. So far, this is the most direct evidence of such cold gas in molecular clouds. The observed H2D+ spectrum can be reproduced with a hydrostatic model with the temperature increasing from about 6K in the centre to almost 10K at the surface. The model is unstable against any increase in the external pressure, and the core is likely to form a low-mass star. The results suggest that an equilibrium configuration is a feasible intermediate stage of star formation even if the larger scale structure of the cloud is thought to be determined by turbulent fragmentation. In comparison with the isothermal case, the inward decrease in the temperature makes smaller, i.e. less massive, cores susceptible to externally triggered collapse.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: molecules - ISM: kinematics and dynamics - ISM: individual objects: ρ Oph, core D (L1696A) - stars: formation

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 777 0
2 NAME [BM89] L1544 cor 05 04 22.5 +25 11 36           ~ 435 1
3 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3338 1
4 NAME Ophiuchus D MoC 16 28 29.2 -24 18 25           ~ 112 0
5 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 298 1

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