Molecular gas and star formation in Lynds 870

Free access article

Issue		A&A Volume 389, Number 2, July II 2002


Page(s)		589 - 602
Section		Diffuse matter in space
DOI		http://dx.doi.org/10.1051/0004-6361:20020621

A&A 389, 589-602 (2002)
DOI: 10.1051/0004-6361:20020621

Molecular gas and star formation in Lynds 870

R. Q. Mao^{1, 2, 3, 4}, J. Yang^{1, 2}, C. Henkel³ and Z. B. Jiang^{1, 2}

¹ Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China
² National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴ Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 106, Taiwan

(Received 17 October 2001 / Accepted 15 April 2002 )

Abstract
We present molecular line and submillimeter dust continuum observations of the Lynds 870 cloud in the vicinity of IRAS 20231+3440 . Two submillimeter cores, SMM1 and SMM2, are identified mapping the 870 $\mu$ m dust continuum and ammonia () emission. The total molecular mass is ~70-110 . The northern core is warmer and denser than the southern one. Molecular outflows are discovered in both cores. In the northern one a significant amount of low velocity (1.3-2.8 ) outflowing gas is found, that is hidden in the relatively broad CO lines but that is revealed by the narrower spectra. While IRAS 20231+3440 is most likely the exciting star of the northern outflow, the driving source of the southern outflow is not detected by infrared surveys and must be deeply embedded in the cloud core. Large scale (~0.2 pc) infall motion is indicated by blue asymmetric profiles observed in the J = 3-2 spectra. Red $K_{\rm s}$ band YSO candidates revealed by the 2MASS survey indicate ongoing star formation throughout the cloud. The calculated masses and the measured degree of turbulence are also reminiscent of clouds forming groups of stars. The excitation of the molecular lines, molecular abundances, and outflow properties are discussed. It is concluded that IRAS 20231+3440 is a Class I object, while the southern core most likely contains a Class 0 source.

Key words: ISM: jets and outflows -- ISM: molecules -- stars: formation -- ISM: individual: Lynds 870 , IRAS 20231+3440

Offprint request: R. Q. Mao, rqmao@jets.pmo.ac.cn

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