EDP Sciences
Free access
Issue
A&A
Volume 463, Number 2, February IV 2007
Page(s) 601 - 610
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:20065139


A&A 463, 601-610 (2007)
DOI: 10.1051/0004-6361:20065139

Hot corinos in NGC 1333-IRAS4B and IRAS2A

S. Bottinelli1, 2, C. Ceccarelli1, J. P. Williams2, and B. Lefloch1

1  Laboratoire d'Astrophysique de l'Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
    e-mail: [sbottine,ceccarel,lefloch]@obs.ujf-grenoble.fr
2  Institute for Astronomy, University of Hawai`i, 2680 Woodlawn Drive, Honolulu HI 96822, USA
    e-mail: jpw@ifa.hawaii.edu

(Received 3 March 2006 / Accepted 11 October 2006 )

Abstract
Context.Complex organic molecules have been detected in massive hot cores for over two decades, and only recently in three hot corinos (the inner regions surrounding Sun-like protostars, where the dust temperature exceeds 100 K). Since hot corinos have sizes of ~100 AU (i.e., of the order of the extent of the Solar System), it is particularly relevant to understand whether they are common and to identify the formation route(s) of complex organic molecules. Much has yet to be learned on this topic, since even recent models predicted it was not possible to form these molecules in low-mass protostars.
Aims.We aim to enlarge the number of known hot corinos and carry out a first comparative study with hot cores. The ultimate goal is to understand whether complex organic molecules form in the gas phase or on grain surfaces, and what the possible key parameters are.
Methods.We observed millimeter rotational transitions of HCOOH, ${\rm HCOOCH_3}$ ${\rm CH_3OCH_3}$ ${\rm CH_3CN}$ and ${\rm C_2H_5CN}$ in a sample of low-mass protostars with the IRAM-30 m. Using the rotational diagram method coupled with the information about the sources' structure, we calculate the abundances of the observed molecules. To interpret these abundances, we review the proposed formation processes of the above molecules.
Results.We report the detection of ${\rm HCOOCH_3}$ and/or ${\rm CH_3CN}$ towards NGC 1333-IRAS4B and NGC 1333-IRAS2A. We find that abundance ratios of O-bearing molecules to methanol or formaldehyde in hot corinos are comparable and about unity, and are relatively (depending on how the ratios are determined) higher than those in hot cores and in Galactic center clouds.
Conclusions.So far, complex organic molecules were detected in all the hot corinos where they were searched for, suggesting that it is a common phase for low-mass protostars. While some evidence points to grain-surface synthesis (either in the cold or warm-up phase) of these molecules (in particular for HCOOH and ${\rm HCOOCH_3}$), the present data do not allow us to disregard gas-phase formation. More observational, laboratory, and theoretical studies are required to improve our understanding of hot corinos.


Key words: ISM: abundances -- ISM: molecules -- stars: formation



© ESO 2007

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.