Issue |
A&A
Volume 442, Number 3, November II 2005
|
|
---|---|---|
Page(s) | 949 - 959 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20042110 | |
Published online | 14 October 2005 |
The circumstellar environment of high mass protostellar objects
III. Evidence of infall?
1
Physics Department, UMIST, P.O. Box 88, Manchester M60 1QD, UK e-mail: [Gary.Fuller;Stewart.Williams]@manchester.ac.uk
2
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA e-mail: tksridha@cfa.harvard.edu
Received:
2
October
2004
Accepted:
27
July
2005
The results are presented of a molecular line survey to search
for the spectral signature of infall towards 77 850 μm continuum
sources believed to be candidate high mass protostellar objects. Up to
six different transitions, HCO+ ,
and
,
H2CO
, N2H+
and H13CO+
, were observed towards each source. Towards the peak of the
850 μm emission, N2H+ was typically strong, with a peak antenna
temperature of ~1.5 K, with a typical linewidth of ~2 km s-1. The
good agreement between the velocity and velocity width of the N2H+
and H13CO+ emission suggests that both species are tracing
similar material in the sources. With respect to the velocity of the
N2H+, there is a statistically significant excess of blue
asymmetric line profiles in both the HCO+
and H2CO
transitions. This excess reaches levels similar to that seen towards
samples of low mass protostars, and suggests that the material around
these high mass sources is infalling. We identify 22 promising candidate
infall sources which show at least one blue asymmetric line profile and
no red asymmetric profiles. The infall velocity is estimated to be in the
range of 0.1 km s-1 to 1 km s-1 with an implied mass accretion rate of
between
/yr and 10-3
/yr.
Key words: stars: formation / ISM: molecules / ISM: HII regions / radio lines: ISM
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.