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Past Events

Event Date Summary
Astronomy Colloquium: Daniela Calzetti Thu. April 13th, 2017
2:30 pm-3:30 pm

The Scales of Star Formation – Insights from the UV
Daniela Calzetti (UMass)

Over two decades of observations from the Ultraviolet to the Infrared with a host of space missions, including the HST, Spitzer, Herschel, GALEX, etc. have enabled us to recover the census of both the intensity and the distribution of star formation within galaxies. This, in turn, is informing us on the physics underlying the links between star formation, feedback, and the natal gas from which stars form. I will present a few results of a recent HST treasury program that is building upon previous findings to shed light on the scales of star formation and their interlinks within galaxies.

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Astronomy Colloquium: Jay Strader Wed. March 22nd, 2017
3:00 pm-4:00 pm

Black Holes in Globular Clusters
Jay Strader (Michigan State University)

Hundreds of stellar-mass black holes form in the early lifetime of a typical globular star cluster. But, unlike the case for neutron stars, no bright X-ray binaries containing black holes have been observed in globular clusters, which led to theoretical predictions that most or all of the black holes should be efficiently ejected through dynamical interactions. I will highlight results from an ongoing survey using deep radio continuum and X-ray data to search for accreting black holes in Milky Way globular clusters, presenting evidence that black holes may indeed be common in globular clusters.

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Astronomy Colloquium: Chris Impey Thu. March 9th, 2017
2:30 pm-3:30 pm

Science Literacy in the MOOC Era
Chris Impey (Arizona)

In a world shaped by science and technology, the persistently low level of science literacy of the general
public is a cause for concern. This talk will look at the science knowledge and beliefs of undergraduates,
using an instrument tethered in the biennial surveys conducted by the NSF for the National Science Board.
Even after taking several science courses, students have only a vague idea of how science works and their
habits of mind are influenced by pseudoscience and easy access online information of dubious quality.

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Astronomy Colloquium: Ian Roederer Wed. March 1st, 2017
3:00 pm-4:00 pm

Heavy Metals from the First Stars to Today
Ian Roederer (UMichigan)

NASA’s Cosmic Origins program aims to address the question, “How did we get here?”  My work addresses this question through three broad themes: the nature of the first stars, the formation and evolution of the Milky Way and Local Group, and the origin of the elements.  I study dwarf galaxies, globular clusters, and stars in the halo using optical and ultraviolet high-resolution spectroscopic data from various telescopes on the ground and the Hubble Space Telescope.  I will present observations of heavy elements that change our understanding of when and how they were first produced in the early Universe,

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Astronomy Colloquium: Nelson Padilla Tue. February 21st, 2017
2:00 pm-3:00 pm

Angular momentum in galaxy formation simulations
Nelson Padilla (U Catolica de Chile)

In this talk I will present studies on the evolution of the angular momentum of galaxies in the EAGLE simulation where we try and identify the mechanisms that contribute to the growth of their angular momentum, including smooth mass accretion, mergers, and mergers with different degrees of alignment with the galaxy’s angular momentum.  We hope to be able to use these results to improve the way in which angular momentum is followed in more simplified models of galaxy formation including SAMs and HODs.

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Astronomy Colloquium: Steinn Sigurdsson Wed. February 15th, 2017
3:00 pm-4:00 pm

How black holes get their kicks: dynamical evolution and coalescence
Steinn Sigurdsson (Penn State U)

Recent observations have increased interest in the possibilities of a significant population of black hole binaries in the local universe. Natal kicks may play a crucial role in the merger rate of stellar mass black holes. Dynamical evolution can lead to an enhanced interaction rate for compact binaries in dense stellar systems and a distinct and richer population of compact binaries. I discuss some of the issues related to black hole binary formation and coalescence, and the issue of retention in globular clusters.

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Astronomy Colloquium: Laura Lopez Wed. January 25th, 2017
3:00 pm-4:00 pm

Observational Assessment of Stellar Feedback in Nearby Galaxies
Laura Lopez (Ohio State U)

Massive stars have a profound astrophysical influence throughout their tumultuous lives and deaths. Stellar feedback – the injection of energy and momentum by stars to the interstellar medium (ISM) – occurs through a variety of mechanisms: radiation, photoionization heating, winds, jets/outflows, supernovae, and cosmic-ray acceleration. Despite its importance, stellar feedback is cited as one of the biggest uncertainties in astrophysics today, stemming from a dearth of observational constraints and the challenges of considering many feedback modes simultaneously. In this talk, I will discuss how a systematic approach to multiwavelength observations can be used to overcome these issues.

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Astronomy Colloquium: Michael Skrutskie Fri. December 9th, 2016
11:00 am-12:00 pm

Diffraction-limited Mid-Infrared Imaging with the 23-meter Large Binocular Telescope
Michael Skrutskie (Virginia)

While the world awaits the construction of the Giant Magellan Telescope, Thirty Meter Telescope, and the European Extremely Large Telescope, the Large Binocular Telescope (LBT) at Mt. Graham, Arizona represents the first operating version of an “Extremely Large Telescope”.  The LBT consists of two 8.4-meter primary mirrors on a single alt-azimuth mount separated, center to center, by 14.4-meters creating an aperture that is nearly 23 meters in extent in one dimension.   The University of Arizona’s Large Binocular Telescope Interferometer (LBTI) coherently combines the light from the two primary mirrors enabling diffraction-limited imaging at a resolution set (on one axis) by the full extent of the 23-meter aperture. 

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Astronomy Colloquium: Monica Valluri Wed. November 30th, 2016
3:00 pm-4:00 pm

Using the Stellar Halo to Probe the Assembly of the Milky Way
Monica Valluri (U Michigan)
Over the next decade there will be an explosion of high quality kinematical data on hundreds of millions of stars in the Milky Way’s stellar halo. We are using cosmological hydrodynamical simulations to explore what we can learn about the detailed assembly history of the Milky Way from these data. We have analyzed orbits of halo stars and correlations between orbital properties and intrinsic stellar properties such as stellar ages and metallicities. I will discuss what halo orbits can tell us about halo assembly.

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Astronomy Colloquium: Kelly Holley-Bockelmann Thu. November 10th, 2016
2:30 pm-3:30 pm

Building Supermassive Black Hole Binaries
Kelly Holley-Bockelmann (Vanderbilt)

Astronomers now know that supermassive black holes reside in nearly every galaxy. Though these black holes are an observational certainty, nearly every aspect of their evolution — from their birth, to their fuel source, to their basic dynamics — is a matter of lively debate. In principle, gas-rich major galaxy mergers are key to generate the central stockpile of fuel needed for a low mass central black hole ‘seed’ to grow quickly and efficiently into a supermassive one. When the black holes in each galaxy meet, they form a supermassive binary black hole,

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Astronomy Colloquium: Ed Moran Wed. October 26th, 2016
3:00 pm-4:00 pm

AGN unification: the hidden truth
Ed Moran (Wesleyan U)

Seyfert galaxies have been traditionally classified into two groups based on the presence (type 1) or absence (type 2) of broad permitted emission lines in their optical spectra.  The discovery of polarized broad lines in a number of narrow-line Seyferts has indicated that such objects are in fact normal Seyfert 1 nuclei whose innermost regions are obscured from our direct view by a dense, torus-like structure.  By establishing a link between the two main classes of Seyfert galaxies, spectropolarimetry has led to significant progress in our understanding of the physics of active galactic nuclei (AGNs). 

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Astronomy Colloquium: Doug Hamilton Fri. October 14th, 2016
11:00 am-12:00 pm

The Origin of Titan and Hyperion
Doug Hamilton (Maryland)

Titan is arguably the Solar System’s most unusual satellite. It is fifty times more massive than Saturn’s other moons and is the only satellite with a substantial atmosphere. Titan shares a unique resonance with nearby Hyperion, but otherwise sits in a particularly large gap between Rhea and Iapetus. Titan has the largest eccentricity of all Saturn’s regular satellites and has a reasonably large orbital tilt; its distant neighbor Iapetus has an even more impressive eight degree free inclination. Hyperion itself is a mystery, with its unusual orbit,

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Astronomy Colloquium: Bill Janesh Wed. September 28th, 2016
3:00 pm-4:00 pm

Needles in a Haystack: Searching for Optical Counterparts to Ultra-compact High Velocity HI Clouds
Bill Janesh (Indiana University)

Low mass galaxies, and particularly those with recent or active star formation, are excellent laboratories to answer questions about galaxy formation and evolution. Due to their faint nature, however, they are difficult to detect. Ultra-compact High Velocity HI Clouds present an opportunity for a targeted search for resolved stellar populations in reservoirs of cold gas in the Local Volume. The recently discovered low-mass star-forming galaxy Leo P is an example of one such object.  We have begun a campaign to obtain deep imaging of a sample of ~50 UCHVCs selected from Arecibo’s ALFALFA HI survey with the aim of detecting or placing constraints on their possible optical counterparts.

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