5 research outputs found
Star Clusters in M31: I. A Catalog and a Study of the Young Clusters
We present an updated catalog of 1300 objects in the field of M31, including
670 likely star clusters of various types. Archival images were inspected to
confirm cluster classifications where possible, but most of the classifications
were based on spectra taken of ~1000 objects with the Hectospec fiber
positioner and spectrograph on the 6.5m MMT. The spectra and images of young
clusters are analyzed in detail in this paper. Ages, reddenings and masses of
140 young clusters are derived by comparing the observed spectra and photometry
with model spectra. We find these to have masses as great as 10^5 with a median
of 10^4 M_sun, and a median age of 0.25 Gyr. Thus these clusters are similar in
mass to the LMC young massive clusters, and are in between Milky Way open
clusters and the globulars of M31 and the Milky Way. Most of the M31 young
clusters have the low concentration typical of Milky Way open clusters, and we
expect that most of these will be disrupted in the next Gyr, but a few have
high concentrations and will likely survive longer. The spatial distribution of
the young clusters is well correlated with the star-forming regions as mapped
out by mid-IR emission. A kinematic analysis likewise confirms the spatial
association of the young clusters with the young disk in M31.Comment: 18 pages of text and figures, 23 of tables, to appear in AJ.
http://www.cfa.harvard.edu/oir/eg/m31clusters/M31_Hectospec.html is a new M31
web site containing tables and postage stamp images of the entire catalo
Deconvolution of Images from BLAST 2005: Insight into the K3-50 and IC 5146 Star-Forming Regions
We present an implementation of the iterative flux-conserving Lucy-Richardson
(L-R) deconvolution method of image restoration for maps produced by the
Balloon-borne Large Aperture Submillimeter Telescope (BLAST). We have analyzed
its performance and convergence extensively through simulations and
cross-correlations of the deconvolved images with available highresolution
maps. We present new science results from two BLAST surveys, in the Galactic
regions K3-50 and IC 5146, further demonstrating the benefits of performing
this deconvolution.
We have resolved three clumps within a radius of 4.'5 inside the star-forming
molecular cloud containing K3-50. Combining the well-resolved dust emission map
with available multi-wavelength data, we have constrained the Spectral Energy
Distributions (SEDs) of five clumps to obtain masses (M), bolometric
luminosities (L), and dust temperatures (T). The L-M diagram has been used as a
diagnostic tool to estimate the evolutionary stages of the clumps. There are
close relationships between dust continuum emission and both 21-cm radio
continuum and 12CO molecular line emission.
The restored extended large scale structures in the Northern Streamer of IC
5146 have a strong spatial correlation with both SCUBA and high resolution
extinction images. A dust temperature of 12 K has been obtained for the central
filament. We report physical properties of ten compact sources, including six
associated protostars, by fitting SEDs to multi-wavelength data. All of these
compact sources are still quite cold (typical temperature below ~ 16 K) and are
above the critical Bonner-Ebert mass. They have associated low-power Young
Stellar Objects (YSOs). Further evidence for starless clumps has also been
found in the IC 5146 region.Comment: 13 pages, 12 Figures, 3 Table