EDP Sciences
Free access
Volume 403, Number 3, June I 2003
Page(s) 1095 - 1100
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030465

A&A 403, 1095-1100 (2003)
DOI: 10.1051/0004-6361:20030465

The protostellar mass limit for 6.7 GHz methanol masers

I. A low-mass YSO survey
V. Minier1, 2, S. P. Ellingsen3, R. P. Norris4 and R. S. Booth2

1  School of Physics, University of New South Wales, Sydney 2052, NSW, Australia
2  Onsala Space Observatory, 439 92 Onsala, Sweden
3  School of Mathematics and Physics, University of Tasmania, Private Bag 21, Hobart 7001, TAS, Australia
4  Australia Telescope National Facility, PO Box 76, Epping 1710, NSW, Australia

(Received 11 December 2002 / Accepted 27 March 2003 )

We report the results of a search for 6.7 GHz methanol masers toward low-mass young stellar objects (YSOs) and (pre)protostellar condensations with the Australia Telescope Compact Array (ATCA). Our sample consisted of 13 class 0 protostars and 44 class I YSOs as well as 66 (pre)protostellar condensations. A single detection was obtained toward NGC 2024: FIR4 in the Orion B region. This is the first detection of a 6.7 GHz methanol maser in Orion. The nature of FIR4 has been a subject of debate with some evidence suggesting that it is a very cold high-mass (pre)protostellar condensation and others arguing that it is a low-mass YSO. The discovery of a methanol maser associated with this source is inconsistent with both of these hypotheses and we suggest that FIR4 probably harbours an intermediate- or high-mass YSO. The less massive objects in our sample do not exhibit any methanol maser stronger than 400 mJy (4 $\sigma$). Based on the nil detection rate toward the low-mass YSOs we can place an upper limit of $3\times10^{6}$ K on the brightness temperature of any methanol maser associated with class 0, I or II sources. These results support the hypothesis that no strong methanol masers are associated with low-mass star formation ( $\la$ $3~M_{\odot}$).

Key words: masers -- stars: formation -- stars: circumstellar matter

Offprint request: V. Minier, vminier@bat.phys.unsw.edu.au

SIMBAD Objects

© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.