Astron. Astrophys. 348, 479-486 (1999)

A cluster of young stellar objects in L1211

M. Tafalla ¹, P.C. Myers ², D. Mardones ³ and R. Bachiller <sup>1

1</sup> Observatorio Astronómico Nacional, Apartado 1143, E-28800 Alcalá de Henares, Spain (tafalla, bachiller@oan.es)
² Harvard-Smithsonian Center for Astrophysics, MS 42, 60 Garden St., Cambridge, MA 02138, USA (pmyers@cfa.harvard.edu)
³ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile (mardones@das.uchile.cl)

Received 19 February 1999 / Accepted 28 May 1999

Abstract

We present millimeter continuum and line observations of a dense core in L1211, a member of the Cepheus cloud complex. We find a small cluster of at least 4 millimeter (mm) sources with no optical counterpart, but each associated with near infrared (NIR) diffuse emission. The strongest mm source has no NIR point-like counterpart, and constitutes a good candidate for a Class 0 object. The other mm objects seem associated with NIR sources and most likely belong to Class I, as also suggested by the spectral energy distributions derived from combining our mm data with IRAS HIRES fluxes. As evidenced by our line data, the mm sources are embedded in an elongated, turbulent core of about 150  of mass and 0.6 pc length. Two of the millimeter sources power bipolar molecular outflows, another signature of their extreme youth. The outflows are well resolved by our observations and seem to have unrelated orientations.

The combination of millimeter sources and bipolar outflow emission indicates that multiple star formation in L1211 has occurred during a short period of time (a few yr). The lack of a noticeable enhancement in the number of NIR sources suggests that the core has not had enough time to form a cluster, so we infer that L1211 is undergoing a first episode of star formation.

Key words: stars: formation ISM: clouds ISM: dust, extinction ISM: individual objects: L1211 ISM: jets and outflows ISM: molecules

Send offprint requests to: M. Tafalla

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Contents

• 1. Introduction
• 2. Observations
• 3. Results
  • 3.1. Continuum data
  • 3.2. Molecular data
    • 3.2.1. The core
    • 3.2.2. The outflows
• 4. Nature of the mm sources and history of star formation in L1211
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: July 26, 1999
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