List of Past LMA/CARMA Seminars : 01-Sep-2010 to 31-Dec-2010

Date:   Mon 13-September-2010
Speaker:   Dr. Dale Frail (NRAO, Charlottesvile)
Title:   TBA

Date:   Friday 24-September-2010
Speaker:   Dr. Gaspar Galaz, (Pontificia Universidad Catolica de Chile; Visiting Professor, UMD)
Title:   "UMD-PUC: A new window to the Southern and Northern Sky"

Date:   Mon 27-September-2010
Speaker:   Dr. David Finkelstein & Dr. Keely Finkelstein (Texas A&M)
Title:  "Searching for the First Galaxies", "Spitzer Observations of Star Formation in Galactic HII Region Environments - Evidence for Triggered Star Formation"

Abstract: We have been able to study galaxies at high redshift for a few decades now, with much being learned about the dominant population of high-redshift galaxies, known as Lyman Break Galaxies (LBGs), at z < 6. Studies of these galaxies imply that they are evolved (i.e., dusty, and harboring older populations), thus we must search elsewhere to find the first galaxies. Galaxies selected on the basis of their Lyman alpha emission were a promising candidate, though only recently have we been able to probe their physical properties. What we have found has been perplexing, as although LAEs tend to be less evolved than LBGs, many appear to have significant dust contents, implying they are not primitive, though an inhomogeneous ISM geometry may be required for Lyman alpha to escape. Near-infrared spectroscopy will put much better constraints on the extinction and metallicities in LAEs, and I will present some very recent results on this front. Lastly, efforts at z = 7 - 9 have recently opened up a new epoch in the early universe. These newly discovered galaxies do appear significantly less evolved than those at lower redshift (i.e. z ~ 3), and they may produce enough ionizing photons to reionize the universe by z ~ 7. However, it does not appear that even the bluest of these galaxies harbor the first stars, thus we must look to z > 10 with JWST to find the first galaxies in the Universe.

Abstract: Most studies of low-mass star formation have focused on regions such as the nearby Taurus- Auriga molecular cloud where stars form in relative isolation, but this is likely not the dominant mode of star formation. Instead a majority of stars form in rich cluster environments with both high and low-mass stars, and the effects of the massive stars can influence how successive generations of new stars form. Understanding these effects is vital to determining how star formation proceeds in rich cluster environments. Using Spitzer Space Telescope mid-IR observations, Young Stellar Objects (YSOs) are identified in four galactic HII regions. The physical distribution of these young protostars and their physical properties are analyzed, via SED fitting, in order to gain better understanding of the relationship between high and low mass stars in HII region environments. These results are used to estimate rates of triggered star formation, which range from 14-58% of the total star formation in these four regions. This suggests that triggered star formation due to HII region expansion is an important mode of star formation.

Date:   Mon 18-October-2010
Speaker:   Dr. Gaspar Galaz (Pontifical Catholic University, Chile)
Title:   "Molecular Gas in Low Surface Brightness Galaxies"

Date:   Thursday 21-October-2010
Speaker:   Dr. Joss Bland-Hawthorn (University of Sydney, Australia)
Title:  "Astrophotonics: the next wave in observational cosmology"

Abstract: Modern astronomy is on the verge of another revolution. The largest optical/infrared telescopes, with diameters up to 10m, are soon to be overtaken by 25-42m behemoths. The most compelling science goals are the detection of faint light from extrasolar planets in orbit around nearby stars and, at the other extreme, the detection of the ?rst star-forming systems in the early universe which is the focus of this talk. The design and construction of the next generation of astronomical instruments presents us with a major challenge. The astronomical community must embrace new technological avenues, in particular, astrophotonics. I will show for the first time a new approach to astronomical instruments which will have application to the applied sciences. I will also feature a new instrument concept GNOSIS that will see first light in 2010.

Date:   Mon 25-October-2010
Speaker:   Dr. Ed Shaya (University of Maryland, MD)
Title:   "The determination of the total masses of nearby galaxies with Numerical Action Method (NAM)"

Date:   Mon 01-November-2010
Speaker:   Thomas Wilson (Naval Research Lab)
Title:  "The sub-mm J=6-5 line of 13CO in Orion"

Following a review of atomic and molecular line data for the Orion KL region, a map of the 13-carbon isotope of carbon monoxide is presented. This was made with an angular resolution of 13 arcseconds with the 10 meter Heinrich-Hertz Telescope on Mt. Graham AZ. A comparison with other high resolution images of CO and other species.

Date:   Mon 08-November-2010
Speaker:   Laura Lopez (UC Santa Cruz)
Title:  "A Study of Stellar Feedback in 30 Doradus"

Abstract: Observations show that star formation is an inefficient and slow process. This result can be attributed to the injection of energy and momentum by stars that prevents free-fall collapse of molecular clouds. The dominant mechanism of this stellar feedback is debated theoretically: possible sources of pressure include the classical warm HII gas, the hot gas shock-heated by supernovae and stellar winds, the direct radiation from stars, and the dust-processed radiation field trapped inside the HII shell. In this talk, I will discuss how one can measure the pressures associated with these feedback processes using multiwavelength imaging (radio, infrared, optical, and X-ray), and I will present the results from applying these techniques to the giant HII region 30 Doradus, the largest star-forming region in the Local Group. For that source, I find that radiation pressure dominates close to the central star cluster, and I will consider the implications regarding the dynamics of 30 Dor and the regulation of star formation in the region.

Date:   Mon 15-November-2010
Speaker:   Shay Storm (UMD)
Title:   "Searching For Variable YSOs in IC 5146"

Date:   Mon 22-November-2010
Speaker:   Open
Title:   ""

Date:   Mon 29-November-2010
Speaker:   David Fisher (UMD)
Title:   "TBA"

Date:   Fri 03-December-2010
Speaker:   Dr. Karin Sandstrom (MPIA)
Title:  "The Spitzer Surveys of the Small Magellanic Cloud: Insights into the Life Cycle of Polycyclic Aromatic Hydrocarbons"

Abstract: I will present the results of two studies investigating the abundance and physical state of PAHs in the Small Magellanic Cloud (SMC). Observations with ISO and Spitzer have shown that PAHs are deficient in low-metallicity galaxies. The SMC provides a unique opportunity to map the PAH emission in a low-metallicity (12 + log(O/H) ~ 8) galaxy at high spatial resolution and sensitivity to learn about the PAH life-cycle. Using mid- and far-IR photometry from the Spitzer Survey of the SMC (S3MC) and mid-IR spectral mapping from the Spitzer Spectroscopic Survey of the SMC (S4MC) we determine the PAH abundance across the galaxy. We find that the SMC PAH abundance is low compared to the Milky Way and variable, with high abundance in molecular regions and low abundance in the diffuse ISM. From the variations of the mid-IR band strengths, we show that PAHs in the SMC are smaller and more neutral than their counterparts in more metal-rich galaxies. Based on the results of these two studies we propose that PAHs in the SMC are formed with a size distribution shifted towards smaller grains and are therefore easier to destroy under typical diffuse ISM conditions. The distribution of PAH abundance in the SMC suggests that PAH formation in molecular clouds is an important process. We discuss the implications of these results for our understanding of the PAH life-cycle both at low-metallicity and in the Milky Way.

Date:   Mon 06-December-2010
Speaker:   Open
Title:   ""

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