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Coexisting conical bipolar and equatorial outflows from a high-mass protostar

Nature volume 396, pages 650–653 (1998)Cite this article

Abstract

The BN/KL region in the Orion molecular cloud1 is an archetype for the study of the formation of stars much more massive than the Sun2. This region contains luminous young stars and protostars but, like most star-forming regions, is difficult to study in detail because of the obscuring effects of dust and gas. Our basic expectations are shaped to some extent by the present theoretical picture of star formation, the cornerstone of which is that protostars accrete gas from rotating equatorial disks and shed angular momentum by ejecting gas in bipolar outflows. The main source of the outflow in the BN/KL region3,4,5 may be an object known as radio source I (ref. 6), which is commonly believed to be surrounded by a rotating disk of molecular material7,8,9. Here we report high-resolution observations of silicon monoxide (SiO) and water maser emission from the gas surrounding source I. We show that within 60 AUof the source (about the size of the Solar System), the region is dominated by a conical bipolar outflow, rather than the expected disk. A slower outflow, close to the equatorial plane of the protostellar system, extends to radii of 1,000 AU.

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Figure 1: Maser spots tracing outflowing gas in the BN/KL region of Orion.
Figure 2: A near-infrared image (at 3.8 µm wavelength) of the region near IRc227, with contours representing 8.4-GHz emission5 and the H2O maser distribution superposed.

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Acknowledgements

We thank M. Reid for assistance in recovering his VLA data, and C. Dougados and K.Menten for permission to use the infrared and radio images presented in Fig. 2 . The National Radio Astronomy Observatory is a facility of the US NSF operated under cooperative agreement by Associated Universities, Inc. C.S. was supported by the NSF REU program. C.R.G. was supported by the NSF Stellar Astronomy and Astrophysics program.

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Author notes

  1. P. J. Diamond

    Present address: Colby College, Waterville, Maine, 04901, USA

Authors and Affiliations

  1. Center for Astrophysics, 60 Garden Street, Cambridge, 02138, Massachusetts, USA

    L. J. Greenhill & J. M. Moran

  2. Department of Physics, University of California, Broida Hall, Santa Barbara, 93106, California, USA

    C. R. Gwinn

  3. Maria Mitchell Observatory, 3 Vestal Street, Nantucket, 02554, Massachusetts, USA

    C. Schwartz

  4. National Radio Astronomy Observatory, PO Box O, Socorro, 87801, New Mexico, USA

    C. Schwartz

Authors
  1. L. J. Greenhill
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  2. C. R. Gwinn
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  3. C. Schwartz
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  4. J. M. Moran
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  5. P. J. Diamond
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Correspondence to L. J. Greenhill.

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Greenhill, L., Gwinn, C., Schwartz, C. et al. Coexisting conical bipolar and equatorial outflows from a high-mass protostar. Nature 396, 650–653 (1998). https://doi.org/10.1038/25299

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