Date: Mon 24-January-2011
Speaker: Open
Title: " "
Date: Mon 31-January-2011
Speaker: Cancelled (Mr. Rodrigo Herrera-Camus)
Title: " "
Date: Mon 07-February-2011
Speaker: Dr. Jonathan Seale (STScI/JHU)
Title: "Spitzer's View of Star Formation in the LMC: Building a Census of the YSOs"
Abstract: The launch of sensitive space-based infrared telescopes such as the Spitzer Space Telescope and, more recently, the Herschel Space Observatory has greatly enhanced our view of star formation in the Magellanic Clouds. The resolution and sensitivity of the instruments is such that studies previously only conducted in the Galaxy can now be preformed in extragalactic environments. In fact, the Large Magellanic Cloud (LMC) is close enough that resolve single instances of star formation or small clusters of forming stars are resolved. Becuase the LMC can be seen in its entirety, this presents a unique statistical oportunity to study the process of star formation on scales ranging from dense molecular clumps (parsec) to the entire galaxy (kiloparsec). Using Spitzer, significant strides have been made in building a complete census of the young stellar object (YSO) population within both Magellanic Clouds. I will summarize recent developments along this front including both photometric and spectroscopic surveys conducted with Spitzer. Besides confirming the YSO-like nature of objects, the spectra also provide a wealth of information regarding the evolutionary state of the YSOs. The youngest sources are dominated by absorption features from silicates and ices, while more advanced YSOs are dominated by PAH and fine-structure line emission from ionized gas, likely from a compact HII region and the surrounding photodissociation region. The ice absorption features can be used to study the ice chemistry around massive YSOs, and the silicate absorption feature is found to correlate with the presence of a surrounding dense molecular clump. With a large sample of objects, it becomes possible to estimate the timescales involved in star formation such as the clump disipation and cluster formation time.
Date: Mon 14-February-2011
Speaker: Dr. Demerese Salter (UMD)
Title: "Millimeter Emission from Protoplanetary Disks: Dust, Cold Gas, and Relativistic Electrons"
Date: Mon 21-February-2011
Speaker: Mr. Rodrigo Herrea-Camus (UMD)
Title: "TBA"
Date: Mon 28-February-2011
Speaker: No Seminar; CARMA Symposium at UC,Berkeley
Title: "TBA"
Date: Mon 07-March-2011
Speaker: Open
Title: ""
Date: Mon 14-March-2011
Speaker: Ms. Katherine Jameson (UMD)
Title: "How are low mass galaxies forming stars? A detailed investigation of star formation in the SMC"
Abstract:From models of galaxy evolution, the canonical star formation law has been shown to be inaccurate, particularly in low metallicity and low mass galaxies. As one of the closest and lowest metallicity galaxies to the Milky Way, the Small Magellanic Cloud (SMC) provides an ideal laboratory for testing the spatially resolved star formation law. We model the dust continuum emission from the infrared data to estimate the molecular hydrogen (H2) column density via the method of Leroy et al. (2007). This avoids the biases introduced by CO as a tracer of H2 in a low metallicity environment. Using the surface density of H2 derived from the dust-continuum, we study the star formation law in the SMC and compare our results to model predictions.
Date: Mon 21-March-2011
Speaker: Spring Break
Title: " "
Date: Mon 28-March-2011
Speaker: Dr. Susan Kassin
Title: "Disk Galaxy Kinematics Over the Last ~8 Billion Years"
Abstract: Observations of the internal kinematics of local galaxies have played a key role in the development of our current picture of galaxy formation. Recently, it has become possible to measure the internal kinematics of large samples of galaxies (~500+) at high redshift (z~1) due to the advent of multi-object spectrographs on 8-meter class telescopes. The focus of this talk will be on the relation between galaxy stellar mass and rotation velocity (the stellar mass Tully-Fisher relation) using data from the DEEP2 Survey. Studying this relation over the last half of the age of the Universe (0.1
Date: Mon 04-April-2011
Speaker: Open
Title: ""
Date: Mon 11-April-2011
Speaker: Dr. Meredith Hughes (UC, Berkeley)
Title: "Millimeter-Wavelength Observations of Circumstellar Disks, and What They Can Tell Us about Planets"
Abstract: Our understanding of the properties of young planetary systems is intimately linked to our knowledge of the structure and evolution of disks around young stars. I will describe how we are using high-resolution observations at millimeter wavelengths to constrain the physical mechanisms driving the dissipation of gas and dust from circumstellar disks, as well as the architectures of the planetary systems they leave behind. I will focus on observations of the later stages of disk evolution. The "transitional" objects intermediate between primordial gas-rich disks and tenuous, dusty debris disks provide a window into the properties of the youngest (Myr-old) planetary systems. The debris disks themselves can point the way to otherwise undetectable plants far from the star, and provide unique dynamical constraints on the masses of directly-imaged planets. I will include a discussion of how next-generation instruments like ALMA are poised to revolutionize the field within the next few years.
Date: Mon 18-April-2011
Speaker: Open
Title: ""
Date: Thurs 21-April-2011
Speaker: Dr. Alexander Kutyrev (GSFC/CRESST)
Title: "High resolution spectroscopy of the zodiacal light"
Abstract:We are developing a high resolution near infrared Fabry-Perot spectrometer for zodiacal light studies. The primary goal of this project is to measure the brightness of the zodiacal light in the near infrared by means of the high resolution Fraunhofer line spectroscopy. The brightness of the zodiacal light in the near infrared is of great importance for cosmological studies when assessing the extragalactic background light (EBL) from the epoque of the early galaxy formation. The results of the COBE DIRBE experiment in the early 90-ies provided an all sky map in the near infrared, but subtracting the zodiacal light contribution for accurate EBL measurement represents a great challenge. Our work on the spectroscopic approach to the problem offers a direct method of measuring the zodiacal light thus eliminating possible systematic uncertainties in the photometric model.
This spectrometer is a product of new developments in high resolution Fabry-Perot interferometry carried out in the Observational Cosmology Lab at Goddard. I will present the results of our project with the first light from the Goddard "backyard" and expected results in connection to previous and ongoing spectroscopic studies of the zodiacal light by other groups.
Date: Mon 25-April-2011
Speaker: Dr. Julia Roman-Duval (STScI/JHU)
Title: "Properties and Structure of Molecular Clouds in the Milky Way and Elsewhere"
Abstract: Understanding the star formation process in the Milky Way and external galaxies requires a good constraint on the physical properties and structure of molecular clouds that give birth to stars and star clusters. I will review the physical properties (mass, radius, density, surface density, etc.) of 750 molecular clouds identified in the Galactic Ring Survey (GRS) and examine their variations with distance to the Galactic Center. I will show that the mass distribution of molecular clouds traces the spiral structure of the Milky Way, and that the decline of their excitation temperature with Galactocentric radius potentially reflects a decrease in star formation rate of 30%/Ro. I will make a quantitative statement on the structure of molecular clouds, in particular on their turbulence spectrum, using Principal Component Analysis. This method has previously been applied to derive turbulence scaling in Galactic molecular clouds, but never on such a large sample of molecular clouds. I will show that turbulence scaling in molecular clouds is consistent with predictions from numerical simulations obeying a log-Poisson turbulence model with 2D shocks as the most dissipative structures, and examine the possible turbulence driving mechanisms. I will briefly touch on the properties of extragalactic molecular clouds of varying metallicities and the prospects for extragalactic turbulence studies in the very near future.
Date: Mon 02-May-2011
Speaker: open
Title: ""
Date: Wed 11-May-2011
Speaker: Erwin de Blok (University of Cape Town, South Africa)
Title: "The South African Square Kilometre Array Precursor MeerKAT"
Abstract: I will describe the South African SKA Precursor MeerKAT, a 64 x 13.5 meter Gregorian offset dish radio interferometer, soon to start construction in the South African Karoo desert. A proto-type for MeerKAT, called KAT-7, is now undergoing commissioning and I will show some of the first results. The first 5 years of MeerKAT's operational life will be dedicated to a number of large Legacy surveys, and I will give a short overview of the planned science.
