Doug Johnstone - Herzberg Institute of Astrophysics, National Research Council of Canada>
Gerald Moriarty Schieven - Joint Astronomy Centre/National Research Council of Canada
& John Bally - University of Colorado
SII image of the L1551 region with contours of 850µm emission
overlaid.
The Taurus molecular cloud complex, one of the closest star-forming
regions at 140pc, is well-known for its low star-formation efficiency,
and sparce low-mass stars.
The exception is the L1551 dark cloud which is the nearest, one of the
best-known, and well studied region of low mass star formation.
This 40 Msol dark molecular cloud contains
at least
one class 0/I protostar (L1551 NE), the archetypical class I outflow
source (L1551 IRS5), several T Tauri (class II) stars including
HL/XZ Tau, and weak T Tauri (class III) stars including UX Tau.
Indeed, X-ray observations have identified at least 38 young stars in
the L1551 cloud.. The
large number of young protostars in a small region is more reminiscent
of a starburst cloud like the ρ Ophiuchi complex, than the rest
of the Taurus cloud complex.
Many of these young protostars are very active. Three (or possibly four)
bipolar molecular outflows are known, including the archetypical L1551 IRS5
flow, at least two jets emanate from the cluster around HL Tau, and strings of
Herbig Haro objects have been determined (through proper motion studies) to
originate from several sources.
Nevertheless, this extemely active and well-studied region has not been
the subject of a large-scale SCUBA study. We have mapped a 20'x20' centered
on IRS5. In addition, because IRS5 is often used as a pointing source and
HL Tau is one of our secondary calibrator sources, we used data mining to
extract all SCUBA data of this region ever taken from the archive and
included those in our data reduction. Image reconstruction was done using
the matrix inversion method described by Johnstone et al
(2000, ApJS, 131, 505), and large-scale (and probably unreal) ripple was
removed using unsharp masking.
The amount of structure visible in the image is remarkable. Above left is
a close-up of the L1551 IRS5 region (full size click here. The two continuum peaks are L1551 IRS5
(right) and L1551 NE (left). The IRS5 outflow also shows up in 850µm
in select regions, particularly at a strong bow shock. To the right is a close-up of the HL/XZ Tau region.
Analysis of these data is in progress, and a paper is in preparation.
back to:> September 2003 Newsletter Index
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