Issue A&A Volume 387, Number 3, June I 2002 Page(s) 931 - 943 Section Formation, structure and evolution of stars DOI http://dx.doi.org/10.1051/0004-6361:20020319

A&A 387, 931-943 (2002)
DOI: 10.1051/0004-6361:20020319

IRAS 05358+3543: Multiple outflows at the earliest stages of massive star formation

H. Beuther¹, P. Schilke¹, F. Gueth^{1, 2}, M. McCaughrean³, M. Andersen³, T. K. Sridharan⁴ and K. M. Menten<sup>1

1</sup>  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
²  Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France
³  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
⁴  Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA

(Received 2 November 2001 /Accepted 28 February 2002 )

Abstract
We present a high-angular-resolution molecular line and millimeter continuum study of the massive star formation site IRAS 05358+3543. Observations with the Plateau de Bure Interferometer in CO 1-0, SiO  and H ¹³CO ⁺ 1-0 reveal at least three outflows which cannot be separated in single-dish data. Observations at millimeter and sub-millimeter wavelengths from the IRAM 30 m telescope and the CSO provide additional information on the region. The most remarkable feature is a highly collimated (collimation factor ~10) and massive ( >10  ) bipolar outflow of ~1 pc length, which is part of a quadrupolar outflow system. The three observed molecular outflows forming the IRAS 05358+3543 outflow system resemble, in structure and collimation, those typical of low-mass star-forming regions. They might therefore, just like low-mass outflows, be explained by shock entrainment models of jets. We estimate a mass accretion rate of ~ /yr, sufficient to overcome the radiative pressure of the central object and to build up a massive star, lending further support to the hypothesis that massive star formation occurs similarly to low-mass star formation, only with higher accretion rates and energetics. In the millimeter continuum, we find three sources near the center of the quadrupolar outflow, each with a mass of 75-100  . These cores are associated with a complex region of infrared reflection nebulosities and their embedded illuminating sources. The molecular line data show that SiO is found mostly in the outflows, whereas H ¹³CO ⁺ traces core-like structures, though likely with varying relative abundances. Thermal CH ₃OH comprises both features and can be disentangled into a core-tracing component at the line center, and wing emission following the outflows. A CO line-ratio study (using data of the J=1-0, 2-1 and 6-5 transitions) reveals local temperature gradients.

Key words: molecular data -- stars: early-type -- stars: formation -- stars: individual: IRAS 05358+3543 -- ISM: jets and outflows

Offprint request: H. Beuther, beuther@mpifr-bonn.mpg.de

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