Issue |
A&A
Volume 413, Number 3, January III 2004
|
|
---|---|---|
Page(s) | 993 - 1007 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20031550 | |
Published online | 07 January 2004 |
The structure of the NGC 1333-IRAS2 protostellar system on 500 AU scales
An infalling envelope, a circumstellar disk, multiple outflows, and chemistry
1
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
2
Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721-0065, USA
3
Division of Geological and Planetary Sciences, California Institute of Technology, MS 150-21, Pasadena, CA 91125, USA
4
Stockholm Observatory, AlbaNova, 106 91 Stockholm, Sweden
Corresponding author: J. K. Jørgensen, joergensen@strw.leidenuniv.nl
Received:
18
June
2003
Accepted:
1
October
2003
This paper investigates small-scale (500 AU) structures of
dense gas and dust around the low-mass protostellar binary
NGC 1333-IRAS2 using millimeter-wavelength aperture-synthesis
observations from the Owens Valley and
Berkeley-Illinois-Maryland-Association interferometers. The detected
mm continuum emission from cold dust is consistent with
models of the envelope around IRAS2A, based on previously
reported submillimeter-continuum images, down to the 3´´, or
500 AU, resolution of the interferometer data. Our data constrain the
contribution of an unresolved point source to 22 mJy. The importance
of different parameters, such as the size of an inner cavity and
impact of the interstellar radiation field, is tested. Within the
accuracy of the parameters describing the envelope model, the point
source flux has an uncertainty by up to 25%. We interpret this point
source as a cold disk of mass
. The same
envelope model also reproduces aperture-synthesis line observations of
the optically thin isotopic species C34S and H13CO+. The
more optically thick main isotope lines show a variety of components
in the protostellar environment: N2H+ is closely correlated with
dust concentrations as seen at submillimeter wavelengths and is
particularly strong toward the starless core IRAS2C. We
hypothesize that N2H+ is destroyed through reactions with CO
that is released from icy grains near the protostellar sources IRAS2A
and B. CS, HCO+, and HCN have complex line shapes apparently
affected by both outflow and infall. In addition to the east-west jet
seen in SiO and CO originating from IRAS2A, a north-south velocity
gradient near this source indicates a second, perpendicular
outflow. This suggests the presence of a binary companion within
(65 AU) from IRAS2A as driving source of this
outflow. Alternative explanations of the velocity gradient, such as
rotation in a circumstellar envelope or a single, wide-angle (
) outflow are less likely.
Key words: ISM: individual objects: NGC 1333-IRAS2 / stars: formation / ISM: molecules / ISM: jets and outflows
© ESO, 2004
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