A&A 392, 1053-1068 (2002)
Constraints on star formation theories from the Serpens molecular cloud
L. Olmi1, 2 and L. Testi3
LMT/GTM Project, Dept. of Astronomy, 815J Lederle GRT Tower B,
University of Massachusetts, 710 N. Pleasant st.
Amherst, MA 01003-9305, USA
University of Puerto Rico, Dept. of Physics, PO Box 23343
University Station, S. Juan PR 00931-3343, USA, and
CNR - Istituto di Radioastronomia, Largo E. Fermi 5,
50125 Firenze, Italy
Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5,
50125 Firenze, Italy
(Received 9 January 2002 / Accepted 24 June 2002 )
We have mapped the large-scale structure of the Serpens cloud core
using moderately optically thick (
CS(2-1)) and optically thin tracers (C
+(1-0)), using the 16-element focal plane array
operating at a wavelength of 3 mm at the Five College Radio Astronomy
Our main goal was to study the large-scale distribution of the molecular
gas in the Serpens region and
to understand its relation with the denser
gas in the cloud cores, previously studied at high angular resolution.
All our molecular tracers show two main gas condensations, or sub-clumps,
roughly corresponding to the North-West and South-East clusters
of submillimeter continuum sources.
We also carried out a kinematical study of the Serpens cloud.
CO and C
O(1-0) maps of the centroid velocity show an increasing,
smooth gradient in velocity from East to West, which we think
may be caused by a global rotation of the Serpens molecular cloud whose
rotation axis is roughly aligned in the SN direction.
Although it appears that
the cloud angular momentum is not sufficient for being dynamically important
in the global evolution of the cluster, the fact that the observed
molecular outflows are roughly aligned with it may suggest a link between
the large-scale angular momentum and the circumstellar disks around
individual protostars in the cluster.
We also used the normalized centroid velocity difference as an infall
indicator. We find two large regions of the map, approximately coincident
with the SE and NW sub-clumps, which are undergoing an infalling motion.
Although our evidence is not conclusive, our data
appear to be in qualitative
agreement with the expectation of a slow contraction followed by a rapid
and highly efficient star formation phase in localized high density regions.
ISM: molecules --
stars: formation --
radio lines: ISM
Offprint request: L. Olmi, email@example.com
SIMBAD Objects in preparation
© ESO 2002