List of Past LMA/CARMA Seminars : 01-Jan-2000 to 01-Jun-2000

Date:   Thu 03-Feb-2000
Speaker:   Rob Swaters (Carnegie Institution of Washington)
Title:  "Dark matter in dwarf and low surface brightness galaxies"

Dwarf and LSB galaxies are usually believed to be dominated by dark matter. Based on new observations of a large sample of these galaxies we found that their rotation curves have shapes similar to those of spiral galaxies. Despite their lower amplitudes, the rotation curves rise steeply until about two disk scale lengths, and start to reach a flat part at larger radii. Mass models based on these rotation curves are consistent with a wide range in their dark matter properties: on the one hand, these rotation curves are consistent with dwarf and LSB galaxies being dominated by dark matter. On the other they may also have dark matter properties similar to those of spiral galaxies.

Date:   Thu 10-Feb-2000
Speaker:   Ronak Yogendra Shah (NRAO & University of Virginia)
Title:  "Evolution and Chemistry in the Serpens Protostellar Cluster"

The northern tip of the Serpens Molecular Cloud is home to a cluster of extremely young cores with remarkably varied emission properties. We observed a two field mosaic surrounding the Class 0 protostellar source, S68N, and the famous outflow source, S68FIR with the BIMA array, concentrating on the and the hyperfine transition of NH2D at 85.926263 GHz, the J=1 -> 0 HCO+ line at 89.188518 GHz, and the 3 mm continuum. Our objective is to understand the relative chemical and physical evolution of these sources with the ammonia deuterium fractionation as well as tracers of outflows, dense gas, cold condensations, and ion--molecule and grain chemistries. For example, we find that the deuterated ammonia traces out a faint ridge of emission east of S68N and S68FIR, potentially tracing out dense cores; breaks up into several sources surrounding the millimeter position of S68N; and is resolved out towards S68FIR. However, much of the HCO+ is found surrounding both sources in an extended envelope, showing less of the clumping, and is not found towards the extended easter ridge of deuterated ammonia emission. With ammonia data from the VLA, we discuss how ammonia deuterium fractionation varies as a function of radius from millimeter continuum peaks and demonstrate how it may constrain the relative influences of grain and ion--molecule chemistries on ammonia throughout the cloud. Furthermore, since deuterated molecules peak in cold, dense gas, we discuss how the ammonia fractionation ratio tracks the evolution of the youngest objects, possibly age-dating regions within the cluster.

Date:   Tue 22-Feb-2000
Speaker:   Laura Woodney (University of Maryland)
Title:   "Morphology of CN and HCN in Comet Hale-Bopp"

Date:   Thu 09-Mar-2000
Speaker:   Richard Barvainis (Division of Astronomical Sciences, NSF)
Title:   "Molecular Gas and Dust at High Redshift"

Date:   Thu 11-May-2000
Speaker:   Denise Smith (Space Telescope Science Institute, Baltimore)
Title:   "A New Probe of the Molecular Gas in Galaxies"

Date:   Tue 16-May-2000
Speaker:   Kartik Sheth (University of Maryland)
Title:   "Comparing Giant Molecular Clouds in M31, M33 and the Milky Way"

Date:   Thu 01-Jun-2000
Speaker:   Bikram Phookun (Raman Research Institute, Bangalore)
Title:   "Kinematic and Morphological Lopsidedness in the HI Distributions of Spiral Galaxies"

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