Thermal Feedback in the High-mass Star- and Cluster-forming Region W51
- National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
- Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands)
- Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg (Germany)
- CASA, University of Colorado, 389-UCB, Boulder, CO 80309 (United States)
- Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)
- Instituto de Radioastronomía y Astrofísica, UNAM, A.P. 3-72, Xangari, Morelia, 58089 (Mexico)
- San Jose State University, One Washington Square, San Jose, CA 95192 (United States)
- European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München (Germany)
- Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom)
- Dept. of Physics, University of Alberta, Edmonton, Alberta (Canada)
- Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom)
High-mass stars have generally been assumed to accrete most of their mass while already contracted onto the main sequence, but this hypothesis has not been observationally tested. We present ALMA observations of a 3×1.5 pc area in the W51 high-mass star-forming complex. We identify dust continuum sources and measure the gas and dust temperature through both rotational diagram modeling of CH{sub 3}OH and brightness-temperature-based limits. The observed region contains three high-mass YSOs that appear to be at the earliest stages of their formation, with no signs of ionizing radiation from their central sources. The data reveal high gas and dust temperatures (T>100 K) extending out to about 5000 au from each of these sources. There are no clear signs of disks or rotating structures down to our 1000 au resolution. The extended warm gas provides evidence that, during the process of forming, these high-mass stars heat a large volume and correspondingly large mass of gas in their surroundings, inhibiting fragmentation and therefore keeping a large reservoir available to feed from. By contrast, the more mature massive stars that illuminate compact H II regions have little effect on their surrounding dense gas, suggesting that these main-sequence stars have completed most or all of their accretion. The high luminosity of the massive protostars (L>10{sup 4} L{sub ⊙}), combined with a lack of centimeter continuum emission from these sources, implies that they are not on the main sequence while they accrete the majority of their mass; instead, they may be bloated and cool.
- OSTI ID:
- 22876110
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 842; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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