Past Events
| Event | Date | Summary |
| Frontiers of Astronomy: Jeremy Darling | Thu. April 2nd, 2020 8:00 pm-9:00 pm |
We regretfully are cancelling this talk due to the COVID-19 outbreak. What is the Universe? What does it contain? What is its history? Its future? This talk will explore the scale, age, and fate of the Universe. We will learn how we observe the Universe, how we know what we know, and what is still not known. We will also explore alternate Universes as a portal to understanding our own. Bio: Jeremy Darling is an Associate Professor of Astrophysics at the University of Colorado, |
| Frontiers of Astronomy: Benne Holwerde | Thu. March 5th, 2020 8:00 pm-9:00 pm |
Star Smog: The role of dust in how we perceive galaxies Galaxies are made up of stars, gas, dark matter and dust. That last ingredient is only a small amount of the total but radically changes our view of galaxies. Up to half the starlight in a given galaxy could be invisible thanks to the small amount of dust. Over decades, astronomy has sought to get away from dust to study the galaxies’ stars and to study the dust itself. This talk will focus on how dust dims and reddens the starlight in galaxies other than our Milky Way. |
| Astronomy Colloquium: Benne Holwerde | Thu. March 5th, 2020 3:00 pm-4:00 pm |
What can the Occult Do for You? Using overlapping galaxies to probe dust properties in galaxies Interstellar dust is still a dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. |
| Astronomy Colloquium: Luca Casagrande | Fri. February 28th, 2020 2:15 pm-3:30 pm |
Cool stars for Galactic archaeology Owing to their long life-times, cool stars can be regarded as fossils from different epochs of the formation and evolution of the Galaxy. To write this narrative, accurate stellar parameters are vital. Here I focus on the importance of photometry to derive stellar parameters, as well as to assess selection functions, and target selection effects in present-day surveys. Cool stars are also characterised by solar like-oscillations, which allow us to determine stellar properties that otherwise we would not have access to. The study of solar-like oscillations is a powerful new tool to investigate stellar populations across the Galaxy, |
| Astronomy Colloquium: Steve Rodney | Fri. February 21st, 2020 2:15 pm-3:30 pm |
Stellar Explosions and Cosmic Lenses A new field of study is opening in astrophysics, at the intersection of strong gravitational lensing and stellar transient science. Very rarely a supernova (SN) or other stellar transient happens to appear in nearly perfect alignment behind a foreground galaxy or cluster. In this case the general relativistic effect of gravitational lensing may boost the transient’s apparent brightness by several magnitudes and cause it to appear as multiple images on the sky. Only a handful of these strongly-lensed transients have been observed to date, but the sample will soon grow to hundreds with upcoming wide-field surveys like LSST and WFIRST. |
| Astronomy Colloquium: Danielle Berg | Fri. February 14th, 2020 2:15 pm-3:30 pm |
Bridging Galaxy Evolution Across Cosmic Time: Tracing the Interplay Between Massive Stars and Their Surrounding Gas with Spectroscopy The first stars and galaxies initiated the epoch of reionization (EoR) and provided the seeds from which all galaxy evolution grew. Knowledge of the properties of these galaxies are needed to understand ionizing photon production and escape, and will provide the crucial missing link needed to weave a coherent picture of galaxy evolution. I will present several programs that are establishing the needed framework to interpret galaxies from z~0‒10, bridging the present-day and early universe. |
| Frontiers of Astronomy: Tabetha Boyajian | Thu. December 5th, 2019 8:00 pm-9:00 pm |
Planet Hunters and the Most Mysterious Star in the Galaxy Abstract: The NASA Kepler Mission provided 4 year long, ultra-precise light curves for over 150,000 stars with a primary science goal of finding transiting planets. In Kepler’s field of view was KIC 8462852, a star citizen scientists identified to have unusual brightness variations. This otherwise seemingly normal F star underwent erratic and completely unpredictable dips in flux ranging from <1% to more than 20%, with each event lasting from days to weeks at a time. In addition to this puzzling variability, |
| Astronomy Colloquium: Tabetha Boyajian | Thu. December 5th, 2019 3:00 pm-4:00 pm |
Planet Hunters and the Most Mysterious Star in the Galaxy (Note: this is a “research-grade” version of Prof Boyajian’s public talk at the Cleveland Museum of Natural History later in the evening.) Abstract: The NASA Kepler Mission provided 4 year long, ultra-precise light curves for over 150,000 stars with a primary science goal of finding transiting planets. In Kepler’s field of view was KIC 8462852, a star citizen scientists identified to have unusual brightness variations. This otherwise seemingly normal F star underwent erratic and completely unpredictable dips in flux ranging from <1% to more than 20%, |
| Frontiers of Astronomy: Chris Mihos | Thu. November 7th, 2019 8:00 pm-9:00 pm |
The Future of the Cosmos Abstract: The universe around us is ever-changing: stars are born and die, galaxies collide and merge with one another, titanic explosions rock our galaxy, and the very fabric of the universe itself expands at an ever-increasing rate, carrying galaxies across the universe at breakneck speeds. In this talk, CWRU Astronomy’s Chris Mihos will give us a peek into the far future, using the physical laws of the universe to explore the changes in store for the Sun, the Galaxy, and the Universe as a whole. Bio: Chris Mihos is a Professor of Astronomy at Case Western Reserve University. |
| Joint Astronomy and EEPS Colloquium: Emilie Dunham | Thu. October 24th, 2019 3:00 pm-4:00 pm |
Meteoritic Implications for the Galactic Environment of Solar System Formation Short-lived radionuclides (SLRs) once present in the solar nebula can be used to probe the Solar System’s galactic formation environment. Isotopic analyses reveal that the first solids formed in the Solar System, calcium- and aluminum-rich inclusions (CAIs) in chondritic meteorites, formed with the live SLRs 10Be (t1/2 = 1.4 Myr) and 26Al (t1/2 = 0.7 Myr). Beryllium-10 is produced when high-energy ions, solar energetic particles or galactic cosmic rays (GCRs), spall nuclei in gas or dust. The most likely source of Solar System 10Be is inheritance of GCR-irradiated protosolar molecular cloud material, Continue reading… Joint Astronomy and EEPS Colloquium: Emilie Dunham |
| Astronomy Colloquium: Sabine Hossenfelder | Thu. October 17th, 2019 3:00 pm-4:00 pm |
Dark matter – or what? In this talk I will explain (a) what observations speak for the hypothesis of dark matter, (b) what observations speak for the hypothesis of modified gravity, and (c) why it is a mistake to insist that either hypothesis on its own must explain all the available data. The right explanation, I will argue, is instead a suitable combination of dark matter and modified gravity, which can be realized by the idea that dark matter has a superfluid phase. |
| Frontiers of Astronomy: Peter James | Thu. October 3rd, 2019 8:00 pm-9:00 pm |
What’s inside the Moon? Abstract: The Moon’s deep interior hides many clues about its formation and evolution. Unfortunately, it is easier to observe a star many light-years away than it is to peer through hundreds of miles of solid rock. We can nevertheless use geophysical techniques like seismic wave propagation, electromagnetic induction, and tidal deformation to learn about the interiors of planetary bodies. This talk will focus on recent exciting developments in the use of gravity anomalies; that is, geographic variations in the strength of the Moon’s gravitational pull, to study the Moon’s interior. |
| Joint Astronomy and EEPS Colloquium: Peter James | Thu. October 3rd, 2019 3:00 pm-4:00 pm |
The crust of Mercury, as seen by the MESSENGER spacecraft NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was the first craft to orbit Mercury, our solar system’s innermost planet. The MESSENGER mission team consisted of scientists from around the globe—including some from CWRU—and the data returned by MESSENGER revealed a planet unlike any other in our solar system. Mercury’s metal core is approximately 80% of the diameter of the planet, so Mercury is a type of a predominantly metal world that be orbiting around other stars. Mercury has a history of pervasive volcanic eruptions (no longer active) with distinct geochemical terranes, Continue reading… Joint Astronomy and EEPS Colloquium: Peter James |
| Astronomy Colloquium: K.S. Dwarakanath | Thu. September 19th, 2019 3:00 pm-4:00 pm |
Diffuse Radio Emission in Galaxy Clusters Galaxy clusters are some of the largest gravitationally bound structures in the Universe. Satellite observations during the early 70’s discovered diffuse X-ray emitting hot gas in the clusters. Cluster-wide non-thermal radio emission was also subsequently discovered in some of the X-ray bright clusters and has been a topic of multi-wavelength studies ever since. This radio emission, which is not associated with any of the cluster galaxies, arises due to relativistic particles and magnetic fields in the Intra Cluster Medium and is extended over millions of light years, |
| Astronomy Colloquium: Narendranath Patra | Thu. September 12th, 2019 3:00 pm-4:00 pm |
The missing satellite problem and the dark galaxies Though the Lambda-CDM model of cosmology has been immensely successful in explaining the observable universe at large scales, several inconsistencies yet persist between its predictions and observations in smaller scales. The `missing satellite’ problem is one of the significant ones. The number of predicted small galaxies within the virial radii of massive galaxies is found to be an order of magnitudes higher than what is observed as luminous satellites of such galaxies. Out of many proposed solutions to this problem, the ‘HVC-minihalo’ |
| Astronomy Colloquium: Johnny Greco | Thu. May 9th, 2019 3:00 pm-4:00 pm |
Low Surface Brightness Galaxies Redux Johnny Greco (Ohio State) |
| Astronomy Colloquium: Zac Berkowicz | Thu. April 18th, 2019 3:00 pm-4:00 pm |
Remote Sensing: from galaxies to deep ocean ridges Often it is too costly, or physically impossible, to take measurements in-situ and one must instead rely on other means to gather the desired information remotely. Such remote sensing techniques are used broadly in Astronomy, after all the telescope is one of the most fundamental remote sensing instruments, but the problem is universal and a host of instruments and practices have been developed and applied to broad ranges of experimental observations. I will describe in some detail the unique challenges and similarities of three remote sensing programs I have participated in: Using FM radio as a radar to probe Ionospheric plasma irregularities (e.g. |
| Frontiers of Astronomy: Stephen Zepf | Thu. April 11th, 2019 8:00 pm-9:00 pm |
Black Holes and Globular Clusters Black Holes have long excited the imagination of both scientists and the broader public. However, black holes are not easy to find because they emit very little light of their own. Often the best way to find a black hole is through its gravitational effect on a very nearby star. Seemingly excellent places to look for these interactions between stars and black holes are globular clusters with many stars all located very close together. I will talk about this search for black holes in globular clusters, |
| Frontiers of Astronomy: Bill Janesh | Thu. March 7th, 2019 8:00 pm-9:00 pm |
Lions, Archers, and Bears: Dwarf Galaxies in the Local Group The Local Group is our cosmic neighborhood — home to the Milky Way, the Andromeda Galaxy, and dozens of smaller objects called dwarf galaxies. Dwarf galaxies are valuable tools for answering questions about how the Universe works. How do stars and galaxies form and change over time? How do galaxies interact with each other? What is a galaxy, anyway? In this talk, we will take a closer look at some of the dwarf galaxies in the Local Group and how they can contribute to our knowledge of the Universe. |
| Astronomy Colloquium: Chelsea Spengler | Mon. January 14th, 2019 2:15 pm-3:15 pm |
Nuclear Star Clusters in Virgo: Scaling relations, stellar populations, and the role of environment It is readily accepted that many galaxies are inhabited by dense, compact objects deep in their centers, manifesting as supermassive black holes and/or nuclear star clusters (NSCs). Their widespread presence and apparent similar scaling relations with properties of their hosts implies that these black holes and NSCs are two related flavours of central massive object that play essential roles in their hosts’ evolution. How do these NSCs form? How do they relate to black holes and their host galaxies? |
| Frontiers of Astronomy: Kelsey Johnson | Thu. December 13th, 2018 8:00 pm-9:00 pm |
How were the most ancient objects in the universe formed? Ancient remnants from the early universe surround our galaxy. These relics, know as “globular clusters” have the potential to provide insight into the prevailing physical conditions during an epoch that cannot be directly observed. While some progress has been made, and we now know globular clusters can still be formed during extreme episodes of star formation in the relatively nearby universe, the actual physical conditions that give rise to globular clusters has vexed both observers and theorists for decades. With the new capabilities of the Atacama Large Millimeter Array (ALMA) we have the ability to probe the birth environments of that gave rise to these ancient objects for the first time. |
| Astronomy Colloquium: Kelsey Johnson | Thu. December 13th, 2018 3:00 pm-4:00 pm |
How were the most ancient objects in the universe formed? Ancient remnants from the early universe surround our galaxy. These relics, known as “globular clusters” have the potential to provide insight into the physical conditions that prevailed during an epoch that cannot be directly observed. We now know that globular clusters can form during extreme episodes of star formation in the relatively nearby universe, but the actual physical conditions that give rise to globular clusters have vexed both observers and theorists for decades. I will overview the discovery and follow-up of pre-natal globular clusters ALMA, |
| Frontiers of Astronomy: Rachel Bezanson | Thu. November 15th, 2018 8:00 pm-9:00 pm |
Galaxy Cannibals: The Evolution of Massive Galaxies Through Cosmic Time Massive galaxies reside in the densest and oldest regions of the Universe, yet we are only beginning to understand their formation history. Once thought to be relics of a much earlier time, the most massive local galaxies are red and dead elliptical galaxies, with little ongoing star formation or organized rotation. In the last decade, observations of their assumed progenitors have demonstrated that the evolutionary histories of massive galaxies have been far from static. Instead, billions of years ago, massive galaxies looked completely different – |
| Astronomy Colloquium: Rachel Bezanson | Thu. November 15th, 2018 3:00 pm-4:00 pm |
The Surprisingly Complex Lives of Massive Galaxies Massive galaxies reside in the densest and most evolved regions of the Universe, yet we are only beginning to understand their formation history. Once thought to be relics of a much earlier epoch, the most massive local galaxies are red and dead ellipticals, with little ongoing star formation or organized rotation. In the last decade, observations of their assumed progenitors have demonstrated that the evolutionary histories of massive galaxies have been far from static. Instead, billions of years ago, massive galaxies were morphologically different: compact, |
| Astronomy Colloquium: Matt Walker | Thu. October 25th, 2018 3:00 pm-4:00 pm |
Dark Matter in the Smallest Galaxies The Milky Way’s dwarf-galactic satellites include the nearest, smallest, darkest and most chemically primitive galaxies known. These properties make them sensitive probes of dark matter physics, if only we can learn their dynamical masses. I will summarize recent results regarding the amount and spatial distribution of dark matter within these systems. I will discuss implications for two lines of inquiry regarding the nature of dark matter: 1) tests of the standard ‘cold dark matter’ paradigm, and 2) searches for dark matter annihilation/decay signals. |
| Frontiers of Astronomy: Benoit Famaey | Thu. October 11th, 2018 8:00 pm-9:00 pm |
Galaxy dynamics: a tale of light and darkness Galaxy dynamics is confronted with one of the deepest problems of modern physics: the dark matter problem. The motions of stars and gas observed exceed what can be explained by the mass visible in those same stars and gas. Either (i) there is a vast amount of unseen mass in some novel form – dark matter – or (ii) the data indicate a breakdown of our understanding of dynamics on the relevant scales, or (iii) both. We shall review the observational evidence for an intimate connection between the baryonic surface density and the total gravitational field in galaxies. |
| Astronomy Colloquium: Guillaume Thomas (Herzberg/NRC) | Thu. October 11th, 2018 3:00 pm-4:00 pm |
CFIS-u : a blue sky for the stellar halo The stellar halo of the Milky Way is an incredible source of information, whether about the formation and the evolution of our Galaxy or to trace the Galactic potential in three dimensions. Indeed, the stellar halo is largely populated by the old metal-poor stars originally lying in satellites galaxies or globular clusters that have being disrupted by tidal effects. The spatial distribution of the different populations of the stellar halo allow us to reconstruct the formation history of the Milky Way, Continue reading… Astronomy Colloquium: Guillaume Thomas (Herzberg/NRC) |
| Astronomy Colloquium: Mousumi Das | Thu. September 20th, 2018 3:00 pm-4:00 pm |
Dark Matter in Galaxy Disks and its Implications for Star Formation in the Outer Regions of Galaxies It is well known that galaxy disks are embedded in massive dark matter halos which make their disks more stable against global disk instabilities. However, there may also be significant amounts of dark matter in galaxy disks as well, as indicated in the early studies of the vertical motion stars in our Galaxy. The disk dark matter is especially important for late type spiral galaxies that have extended neutral hydrogen (HI) gas disks, |
| Astronomy Colloquium: Sally Oey | Tue. September 11th, 2018 3:00 pm-4:00 pm |
Toward Understanding Feedback from Local Lyman Continuum-Emitting Galaxies The fate of Lyman continuum (LyC) radiation from massive stars is a problem of fundamental importance to both galaxy evolution and cosmic evolution. What conditions and feedback processes allow these ionizing photons to escape their host galaxies? Only small samples of local LyC emitters are currently known, including a few nearby starburst galaxies and extreme Green Pea galaxies. They generally appear to be very young, intense, and compact starbursts triggered by galaxy mergers, and forming super star clusters. I will present what we’re starting to learn about the mechanical and radiative feedback in these systems, |
| Research Talk: Sandeep Kumar Kataria | Mon. July 30th, 2018 4:00 pm-5:00 pm |
The Impact of Bulges on Bar Formation and Bar Pattern Speed in Disk Galaxies We use N-body simulations of bar formation in an isolated galaxy to study the effect of bulge mass and bulge concentration on bar formation and bar pattern speed. Two sets of models are generated, one that has a dense bulge and high surface density disk and a second model that has a less concentrated bulge and a lighter disk. Our simulations of both the models show that there is an upper cut-off in bulge to disk mass ratio Mb/Md above which bars cannot form; |
| Astronomy Colloquium: Keren Sharon | Tue. April 24th, 2018 2:30 pm-3:30 pm |
The Universe, Magnified: The Power of Gravitational Lensing |
| Frontiers of Astronomy: Other Earths and Origins of Life | Thu. April 12th, 2018 8:00 pm-9:00 pm |
Other Earths and Origins of Life The lecture will discuss the new field of scientific research on the emerging frontier where astronomy meets biochemistry. In the past year astronomers have discovered planets that resemble Earth around nearby stars and now prepare to explore them with a new generation of telescopes. In the meantime, chemists and biologists have narrowed down the environments necessary for early forms of Earth life and are helping the astronomers in defining their targets. The search is on! Continue reading… Frontiers of Astronomy: Other Earths and Origins of Life |
| Astronomy Colloquium: Dimitar Sasselov | Thu. April 12th, 2018 4:00 pm-5:00 pm |
Ocean Worlds: from Familiar to Exotic and Extreme Planets (Note special day and time) |
| Frontiers of Astronomy: The New Moon | Thu. March 1st, 2018 8:00 pm-9:00 pm |
The New Moon Although we may not think of the Moon as a dynamic place (the first lunar explorers described the landscape’s “magnificent desolation”), its past was one of intense bombardment, floods of lavas, and intrusive volcanism, and even today it continues to change. Understanding the Moon’s past and present may provide our best opportunity to gain new insights topics as diverse as the early evolution of the Solar System and the timeline of the first development of life on Earth. The Moon also yields insights into how a planetary body evolves from a fiery magma ocean to a solid world still cooling off today, |
| Astronomy Colloquium: Brett Denevi | Thu. March 1st, 2018 2:30 pm-3:30 pm |
Our Goals for Lunar Science and Exploration NASA has recently announced plans to refocus its attention on the Moon as a cornerstone for Solar System science and exploration. However, similar announcements were made in the not-so-distant past, only to be cancelled before they could come to fruition. What have we learned along the way? And what can we learn from new orbital and landed missions to the Moon? I will present recent highlights in lunar science, the highest priority lunar science goals as determined by the National Research Council, and some of the ways we will seek to answer those questions. |
| Astronomy Colloquium: Caitlin Casey | Tue. February 13th, 2018 2:30 pm-3:30 pm |
The Universe’s Most Extreme Star-Forming Galaxies in the Most Extreme Environments Dusty star-forming galaxies host the most intense stellar nurseries in the Universe. Their unusual characteristics (star formation rates of 200-2000 Msun/yr, compared to the Milky Way’s 1 Msun/yr) pose a unique challenge for cosmological simulations of how galaxies form and evolve, particularly in the first few billion years after the Big Bang. Although rare today, these unusual galaxies were factors of 1000 times more prevalent 10 billion years ago, contributing significantly to the buildup of the Universe’s stars during catastrophic galaxy-galaxy collisions that ignited shortlived but extremely powerful bursts of star formation. |
| Astronomy Colloquium: Cameron McBride | Tue. January 30th, 2018 2:30 pm-3:30 pm |
Data Science: The what, why, and how of my transition from Science to Tech Data science continues to explode as a field as the industrial need for scientific rigor grows. It can be referred to by many names: machine learning, artificial intelligence, statistics, science, or sometimes even software engineering. I trained to be an academic scientist, and did research in extragalactic astronomy and cosmology across four major research institutions and as part of an international collaboration. Over the past three years, I have worked for two startups and a larger corporation solving challenging problems across two fields. |
| Astronomy Colloquium: Jillian Scudder | Tue. January 16th, 2018 2:30 pm-3:30 pm |
Title: The hunt for cosmic monsters: understanding galaxies in the confused FIR sky Observing galaxies in the Far-Infrared (FIR) gives us a unique window into the star formation rates of very high redshift, dusty galaxies. These galaxies are generally thought to be forming stars at a prodigious rate, heating their dust within their host galaxy, which then radiates in the FIR. However, observing this luminous dust is difficult, even with a space-based telescope such as the Herschel Space Observatory, as the resolution of the images returned is quite poor. It is often assumed that a bright source in the FIR belongs to a single, |
| Astronomy Colloquium: Mark Vogelsberger | Thu. December 14th, 2017 3:00 pm-4:00 pm |
Simulating Galaxy Formation: IllustrisTNG and beyond In my talk I will describe recent efforts to model the large-scale distribution of galaxies with cosmological hydrodynamics simulations. I will focus on the Illustris simulation, and our new simulation campaign, the IllustrisTNG project. After demonstrating the success of these simulations in terms of reproducing an enormous amount of observational data, I will also talk about directions for further improvements over the next couple of years. |
| Frontiers of Astronomy: Simulating the Universe | Thu. December 14th, 2017 8:00 pm-9:00 pm |
Simulating the Universe Continue reading… Frontiers of Astronomy: Simulating the Universe |
| Astronomy Colloquium: Ben Monreal | Tue. December 5th, 2017 3:00 pm-4:00 pm |
hWAET: a ground-based telescope for exoplanet direct imaging In the literature on telescope conceptual design, there is a divide which at first glance seems unusual: space telescope design is a free-for-all while ground based concepts are very conservative. As an instrument-builder, although most of my work is on neutrinos and dark matter I am also wading into the understudied edges of ground-based telescope design. In this talk, I will introduce WAET, a new (but still fairly conservative) construction concept for large ground-based optical/IR telescopes. WAET is intended to use conventional components and prescriptions to get to huge apertures at extremely low cost. |
| Astronomy Colloquium: Phil Hopkins | Fri. November 17th, 2017 2:00 pm-3:00 pm |
Stars Re-Shaping Galaxies The most fundamental unsolved problems in galaxy formation revolve around “feedback” from massive stars and black holes. I’ll present new results from the FIRE simulations which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from stellar radiation pressure, supernovae, stellar winds, and photo-ionization. These mechanisms lead to ‘self-regulated’ galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law and the global inefficiency of star formation — the stellar mass function — |
| Frontiers of Astronomy: The Universe on A Computer: The Formation of Galaxies, Stars, and Planets in a Violent Cosmos | Thu. November 16th, 2017 8:00 pm-9:00 pm |
The Universe on A Computer: The Formation of Galaxies, Stars, and Planets in a Violent Cosmos Astronomers have now discovered planets around distant stars, the relics of the “first generation” of stars in the Universe, and the light from the first galaxies when the Universe was but a fraction of its present age. However, a human life is infinitesimally small compared to the cosmic time scales over which these systems evolved, so we see only snapshots, instants in time. To link them together and understand how our Universe evolved, |
| Astronomy Colloquium: Jason Wright | Tue. November 7th, 2017 3:00 pm-4:00 pm |
The Puzzle of Boyajian’s Star I have been at the center of efforts to understand KIC 8462852, a strange star found during the Kepler mission. It exhibits deep, irregular “dips” or dimming events lasting days, up to 22% in depth, and appears to be dimming secularly on decadal timescales. As ever-more-contrived natural explanations are proposed and explored by my team and others, we continue to put together monitoring and target-of-opportunity programs to catch it “in the act” of dipping and determine the nature of the dips. I will discuss the families of possible solutions for this star, |
| Astronomy Colloquium: David Silva | Fri. October 13th, 2017 11:00 am-12:00 am |
NOAO Today and Tomorrow The National Optical Astronomy Observatory (NOAO) is the U.S. national center for ground-based optical-infrared (OIR) astronomy. It is a Federally Funded Research and Development Center (FFRDC) sponsored by the National Science Foundation (NSF) and managed by the Association of Universities for Research in Astronomy (AURA). The NOAO mission is to enable discovery for the research community-at-large through open access to world-class facilities, capabilities, services, and data products. At NSF request, AURA is developing a plan to create the National Center for OIR Astronomy (NCOA) by restructuring the Gemini Observatory, |
| Frontiers of Astronomy: Mapping the Universe: New Vistas, New Lands | Thu. October 12th, 2017 8:00 pm-9:00 pm |
Mapping the Universe: New Vistas, New Lands To be human is to explore. Today’s astronomers are cosmic explorers, creating maps of the Universe, near and far. The earliest star maps were painted thousands of years ago on the walls of caves. Our maps today are spectacular, full of objects and phenomena that were completely undiscovered even 20 years ago. Yet, great mysteries remain. Is a civilization ending asteroid lurking in the darkness? Do Earth‐like planets orbit nearby stars and do they harbor life? How did our home galaxy, the Milky Way, Continue reading… Frontiers of Astronomy: Mapping the Universe: New Vistas, New Lands |
| Astronomy Colloquium: Annika Peter | Mon. September 25th, 2017 1:30 pm-2:30 pm |
Twinkle, twinkle, little galaxy The littlest galaxies have the potential to tell us the most about the nature of dark matter and about star formation in extreme environments. In this talk, I describe what they are telling us already, what the open questions are, and my approach to answering them. I will highlight new opportunities with the next generation of astronomical surveys. |
| Astronomy Colloquium: Amanda Kepley | Tue. September 12th, 2017 3:00 pm-4:00 pm |
Opening New Frontiers in the Study of Star Formation with the Next Generation of Radio Telescopes |
| Frontiers of Astronomy: The Frontier From Space | Thu. April 13th, 2017 8:00 pm-9:00 pm |
The Frontier From Space In 2015 the Hubble Space Telescope celebrated its 25th anniversary. Hubble has produced a paradigm shift in how both astronomers and the general public understand the Universe, and it may be time to take stock of all the accomplishments of the many space missions undertaken by numerous agencies — ESA and NASA in particular — over the past 30 years. We will do this with an eye to set the stage for the next game‐changing space missions. Daniela Calzetti is Professor of Astronomy at the Department of Astronomy, Continue reading… Frontiers of Astronomy: The Frontier From Space |
| Astronomy Colloquium: Daniela Calzetti | Thu. April 13th, 2017 2:30 pm-3:30 pm |
The Scales of Star Formation – Insights from the UV 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. |
| Astronomy Colloquium: Jay Strader | Wed. March 22nd, 2017 3:00 pm-4:00 pm |
Black Holes in Globular Clusters 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. |
| Frontiers of Astronomy: Our Future Off-Earth | Thu. March 9th, 2017 8:00 pm-9:00 pm |
Our Future Off-Earth The Space Age is half a century old. Its early successes were driven by a fierce superpower rivalry between the Soviet Union and the United States, which tended to obscure the fact that exploration and risk‐taking is built into human DNA. Decades after we last set foot on the Moon, and several years after the Space Shuttle was retired, the space activity is finally leaving the doldrums. A vibrant private sector led by SpaceX and Virgin Galactic plans to launch supplies cheaply into Earth orbit and give anyone the chance of a sub‐orbital joy ride. Continue reading… Frontiers of Astronomy: Our Future Off-Earth |
| Astronomy Colloquium: Chris Impey | Thu. March 9th, 2017 2:30 pm-3:30 pm |
Science Literacy in the MOOC Era In a world shaped by science and technology, the persistently low level of science literacy of the general |
| Astronomy Colloquium: Ian Roederer | Wed. March 1st, 2017 3:00 pm-4:00 pm |
Heavy Metals from the First Stars to Today 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, |
| Astronomy Colloquium: Nelson Padilla | Tue. February 21st, 2017 2:00 pm-3:00 pm |
Angular momentum in galaxy formation simulations 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. |
| Astronomy Colloquium: Steinn Sigurdsson | Wed. February 15th, 2017 3:00 pm-4:00 pm |
How black holes get their kicks: dynamical evolution and coalescence 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. |
| Astronomy Colloquium: Laura Lopez | Wed. January 25th, 2017 3:00 pm-4:00 pm |
Observational Assessment of Stellar Feedback in Nearby Galaxies 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. |
| 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 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. |
| Frontiers of Astronomy: The Quest for Infinite Telescope Aperture: Are We There Yet? | Thu. December 8th, 2016 8:00 pm-9:00 pm |
The Quest for Infinite Telescope Aperture: Are We There Yet? Michael Skrutskie, University of Virginia Since the invention of the telescope somewhere in the Netherlands around the end of the 16th century one thing has generally mattered most to builders and users of these instruments… larger apertures collect more light and reveal finer detail, ultimately opening the door to studies ranging from observations of the most distant observable universe, the direct detection and characterization of extrasolar planets, and “spacecraft quality” observations of Solar System objects. Individual institutions, entire nations, and now consortia of nations are striving to build bigger and better telescopes. |
| 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 |
| Astronomy Colloquium: Kelly Holley-Bockelmann | Thu. November 10th, 2016 2:30 pm-3:30 pm |
Building Supermassive Black Hole Binaries 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, Continue reading… Astronomy Colloquium: Kelly Holley-Bockelmann |
| Frontiers of Astronomy: A Space‐time Symphony of Gravitational Waves | Thu. November 10th, 2016 8:00 pm-9:00 pm |
A Space‐time Symphony of Gravitational Waves On February 11, 2016, scientists announced the first detection of gravitational waves, a Nobel Prize‐level achievement and a profound moment for humankind. Prior to that moment, the only way we learned about the distant Universe is through the light we received. Light revealed that we live in an extraordinarily beautiful expanding and accelerating Universe — full of exoplanets, stellar explosions, other galaxies, and dark matter that pervades everything. And now, humanity has observed the ripples in space‐time caused by the motion of massive objects like black holes; Continue reading… Frontiers of Astronomy: A Space‐time Symphony of Gravitational Waves |
| Astronomy Colloquium: Ed Moran | Wed. October 26th, 2016 3:00 pm-4:00 pm |
AGN unification: the hidden truth 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). |
| Astronomy Colloquium: Doug Hamilton | Fri. October 14th, 2016 11:00 am-12:00 pm |
The Origin of Titan and Hyperion 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, |
| Frontiers of Astronomy: Pluto’s Lonely Ice Cap | Thu. October 13th, 2016 8:00 pm-9:00 pm |
Pluto’s Lonely Ice Cap Doug Hamilton, University of Maryland The icy white heart of Pluto became an instant sensation after the 2015 New Horizons flyby, featured on websites, blogs, and T‐shirts worldwide. The actual feature on Pluto is composed of frozen nitrogen, carbon monoxide, and methane, substances that can all be either in the solid or gaseous states at the cold temperatures of this distant world. Water plays the same role on Earth, being found as a solid in our twin polar ice caps, and Mars too has a pair of polar caps composed, Continue reading… Frontiers of Astronomy: Pluto’s Lonely Ice Cap |
| 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 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. |
| Frontiers of Astronomy: Biography of the Milky Way | Thu. April 14th, 2016 8:00 pm-9:00 pm |
Biography of the Milky Way James Bullock, University of California, Irvine The Universe on the grandest scales is a vast network of galaxies. Dotted along an expanding cosmic web, galaxies shine with the collective light of thousands to billions of stars. More than just collections of stars however, galaxies are dynamic ecosystems. They allow multiple generations of stars to build new atoms that had never before existed. They foster complex chemistry, even organic chemistry, in an otherwise sterile universe. One galaxy, the Milky Way, is special to us. Without it, we would not exist. Continue reading… Frontiers of Astronomy: Biography of the Milky Way |
| Astronomy Colloquium: James Bullock | Wed. April 13th, 2016 11:00 am-12:00 pm |
Cosmology and the Local Group The Local Group and the tiny galaxies that surround the Milky Way provide unique and detailed data sets for testing ideas in cosmology and galaxy formation. In this talk I will discuss how numerical simulations coupled with local “near-field” observations are informing our understanding of dark matter, the formation of the first galaxies, and the physical processes that act at the threshold of galaxy formation. |
| Astronomy Colloquium: Hongsheng Zhao | Mon. April 11th, 2016 11:00 am-12:00 pm |
New Physics Beyond Galaxies I will show how current data on galaxies and clusters could be used to constrain the new physics of dark matter and relativity. I will propose a new theoretical approach to integrate MOND and Dark Matter. |
| Astronomy Colloquium: Elena D’Onghia | Wed. March 30th, 2016 11:00 am-12:00 pm |
The Structure and Dynamics of the Milky Way Stellar Disk Ongoing surveys are revolutionizing our understanding of Galaxy dynamics. At the same time, advances in computational cosmology have led to improved predictions for the properties of galaxies in the LCDM theory. This simultaneous progress has transformed the field of the dynamics of the Milky Way and its dwarf galaxies into a powerful testing ground for both cosmological and galaxy formation theories. One important result of the last decades is that cosmological simulations of the Milky Way overpredict by a large factor the number of dwarf satellite galaxies orbiting our Galaxy. |
| Astronomy Colloquium: Kevin Stevenson | Wed. March 16th, 2016 11:00 am-12:00 pm |
Today’s Exo-Weather Forecast: Hot and Humid with a Chance of Clouds Planet-finding surveys have revealed thousands of confirmed exoplanets and candidates awaiting verification. Many of these objects were discovered indirectly using the transit technique, which is a powerful tool that has transformed our understanding of planetary system architecture. Furthermore, this technique has provided extraordinary insights into some of these planets’ atmospheric compositions and thermal structures, thus revealing unexpected discoveries and altering our perspective of these worlds. One of the most outstanding challenges in exoplanet characterization is understanding the prevalence of obscuring clouds and hazes in their atmospheres. |
| Astronomy Colloquium: Kathryn Johnston | Thu. March 3rd, 2016 3:00 pm-4:00 pm |
Dark Matter and Stellar Halos around Galaxies: Formation, Histories and Structure The existence of spectacular low-surface-brightness features – remnants of past mergers – surrounding many galaxies has been known about for many decades. A major accomplishment for more recent, large scale stellar surveys of the Milky Way has been the discovery of a multitude of debris from dead and dying small satellites encircling our own Galaxy. While these structures contain less than 1% of the light in the Universe and an even smaller fraction of the total mass their properties can be used to address fundamental topics, |
| Frontiers of Astronomy: Galactic Cannibalism | Thu. March 3rd, 2016 8:00 pm-9:00 pm |
Galactic Cannibalism Kathryn Johnston, Columbia University Galaxies! Images of these objects are awe-inspiring – spirals of billions of stars, along with the gas and dust from which stars form, spinning slowly in the sky. Yet these majestic objects are thought to have formed quite violently through the agglomeration of smaller objects. Even our own home – the Milky Way galaxy – seems to be in the process of devouring several smaller galaxies! This talk examines why we think galaxies are cannibals in general, and what this means about the past and future evolution of the Milky Way in particular. Continue reading… Frontiers of Astronomy: Galactic Cannibalism |
| Joint Phys/Astro Colloquium: John Monnier (Cancelled) | Thu. February 25th, 2016 4:15 pm-5:15 pm |
Cancelled due to inclement weather. |
| Astronomy Colloquium: Adam Leroy | Wed. February 17th, 2016 11:00 am-12:00 pm |
Star Formation-Driven Molecular Superwinds as Understood From the Two Nearest Starburst Galaxies (and a Small Survey) I will use the two nearest starburst galaxies: M82 and NGC 253 as examples to discuss the origin and fate of galaxy-scale molecular outflows driven by star formation. Outflows of interstellar gas driven by stellar feedback should be a key element in the interaction between galaxy disks and the huge reservoirs of gas and dust in the circumgalactic medium. They should carry metals and dust out of galaxy disks and may deplete future fuel for star formation. |
| Astronomy Colloquium: Tony Sohn | Wed. February 3rd, 2016 11:00 am-12:00 pm |
Dynamics of Local Group Galaxies via HST Proper Motions The Universe evolves hierarchically with small structures merging and falling in to form bigger structures. Due to its proximity, the Local Group (LG) is the best place to witness and study these hierarchical processes in action as evidenced by e.g., the many stellar streams found around the Milky Way and M31. Stellar systems in the LG have therefore become the benchmark for testing many aspects of cosmological theories. Despite the advances in both observational and theoretical areas in the last decade or so, |
| Astronomy Colloquium: Kristen McQuinn | Wed. January 13th, 2016 11:00 am-12:00 pm |
Leo P: Galaxy Evolution at the Faint-end of the Luminosity Function Theories of galaxy evolution have been tested by our a growing knowledge of low-mass galaxies. Much of the progress has been made studying the closest of satellites whose histories are inextricably linked to their massive host galaxy. Finding isolated galaxies to populate the faint-end of the luminosity function outside our group environment means looking farther afield – a task which has proven unavoidably problematic due to the intrinsic faintness of the systems. One such galaxy, Leo P, has been discovered through the blind HI ALFALFA Survey. |
| Frontiers of Astronomy: Gamma Ray Bursts: The Biggest Explosions Since the Big Bang | Thu. December 10th, 2015 8:00 pm-9:00 pm |
Gamma Ray Bursts: The Biggest Explosions Since the Big Bang Edo Berger, Harvard University Representing Nature’s biggest explosions since the Big Bang itself, gamma-ray bursts were first accidentally spotted in the 1960s by Department of Defense satellites hunting for terrestrial nuclear blasts. Prof. Berger will describe the ensuing decades-long quest to decipher the origin and energy source of these mysterious explosions. Edo Berger is a professor of astronomy at Harvard University. He received his B.S. degree from the University of California, Los Angeles in 1999, and his Ph.D. from the California Institute of Technology in 2004. |
| Astronomy Colloquium: Edo Berger | Thu. December 10th, 2015 3:00 pm-4:00 pm |
Short-Duration Gamma-Ray Bursts and the Electromagnetic Counterparts of Gravitational Wave Sources Gamma-ray bursts are the most luminous and energetic explosions known in the universe. They appear in two varieties: long- and short-duration. The long GRB result from the core-collapse of massive stars, but until recently the origin of the short GRBs was shrouded in mystery. In this talk I will present several lines of evidence that point to the merger of compact objects binaries (NS-NS and/or NS-BH) as the progenitor systems of short GRBs. Within this framework, the observational data allow us to determine the merger rate of these systems as input to Advanced LIGO, |
| Astronomy Colloquium: Kevin Croxall | Wed. December 2nd, 2015 11:00 am-12:00 pm |
Oxygen in the Local Universe: Establishing Order through CHAOS The metal content of a galaxy is one of the most important properties used |
| Frontiers of Astronomy: The History of the Milky Way Written in the Stars | Thu. November 12th, 2015 8:00 pm-9:00 pm |
The History of the Milky Way Written in Stars Jennifer Johnson, Ohio State University Our Galaxy, the Milky Way, did not always look as it does now, a multi-armed spiral galaxy with at least one neighborhood hospitable to life. The Galaxy has been growing and evolving for the last 13 billion years, creating billions of stars throughout its life. These stars, through their age, chemical composition, and motions, record the history of the Galaxy and provide a “fossil record” if we can observe enough of it to interpret it. The Sloan Digital Sky Survey has been observing stars, Continue reading… Frontiers of Astronomy: The History of the Milky Way Written in the Stars |
| Astronomy Colloquium: Jennifer Johnson | Thu. November 12th, 2015 3:00 pm-4:00 pm |
The Secret Lives of Stars: Galactic History from the APOGEE Survey The history of a galaxy can be traced through its stars: their compositions, their ages, and their motions. The Milky Way provides an ideal case for performing detailed Galactic archaeology to investigate the evolution of spiral galaxies. The SDSS-APOGEE spectroscopic survey, using a high-resolution, multi-object NIR spectrograph, has observed ~150,000 stars in the Galaxy, with particular emphasis on red giants in the Kepler field and in the dust-obscured regions of the disk and bulge. I will discuss how we are using spectroscopic and asteroseismic results to understand metallicity gradients, |
| Astronomy Colloquium: Benoit Famaey | Wed. October 21st, 2015 11:00 am-12:00 pm |
Galactoseismology in the Milky Way Benois Famaey, CNRS/Strasbourg Current Galactic dynamical models still often rely on the zeroth order assumptions of a smooth time-independent and axisymmetric gravitational potential. First order perturbed models are those trying to isolate the effects of one main perturber, such as the bar or the spiral arms. In this talk, we show how a single internal perturber can generate horizontal and vertical bulk motions, in the form of “galactoseismic” oscillation modes. We also show that non-linear couplings can be present when multiple perturbers are taken into account simultaneously. We argue that, |
| Frontiers of Astronomy: 25 Years of the Hubble Space Telescope | Thu. October 15th, 2015 8:00 pm-9:00 pm |
25 Years of the Hubble Space Telescope Frank Summers, Space Telescope Science Institute In April 1990, astronauts aboard the Space Shuttle Discovery deployed the Hubble Space Telescope into Earth orbit, and launched a new era of astronomical discovery. Now, 25 years later, we celebrate a remarkable milestone for a space observatory whose ground-breaking investigations have brought revolutionary changes in our understanding from planets, stars, nebulae, and galaxies to the very frontiers of the cosmos. Explore the trials and triumphs of NASA’s first Great Observatory, and experience a compendium of some of the greatest imagery the universe has ever known. Continue reading… Frontiers of Astronomy: 25 Years of the Hubble Space Telescope |
| Astronomy Colloquium: Frank Summers | Wed. October 14th, 2015 11:00 am-12:00 pm |
Frank Summers (STScI) The presentation of complex scientific ideas demands both precision and detail. The interpretation of even graphical representations generally requires specialized knowledge. Public-level visuals are difficult, and risk becoming over-simplified cartoon versions. Astronomy, however, has gained favor with the public for its awe-inspiring images from the Hubble Space Telescope and other observatories. That visual splendor attracts a wide audience, creating a much smoother and natural entry into scientific topics. Dr. Summers follows this path in creating astronomy visualizations that both engage and inform the public. |
| Astronomy Colloquium: Gail Zasowski | Wed. September 30th, 2015 11:00 am-12:00 pm |
Gail Zasowski (Johns Hopkins University) One of the critical components for understanding galaxy evolution is understanding the Milky Way Galaxy itself — its detailed structure and chemodynamical properties, as well as fundamental stellar physics, which we can only study in great detail locally. This field is currently undergoing a dramatic expansion towards the kinds of large-scale statistical analyses long used by the extragalactic and other communities, thanks in part to the enormous influx of data from multiple large space- and ground-based surveys. I will describe the Milky Way and Local Group in the context of general galaxy evolution and highlight some recent developments in Galactic astrophysics that take advantage of these big data sets and analysis techniques. |
| Astronomy Colloquium: David Merritt | Wed. September 9th, 2015 11:00 am-12:00 pm |
How Things Get Into (Supermassive) Black Holes David Merritt, Rochester Institute of Technology Gas near the center of a galaxy can find its way into the central black hole without much difficulty, but stars need to be nudged. The so-called “loss-cone problem” is well understood in the case of random gravitational encounters between the stars. But sufficiently close to a nuclear black hole, classical loss-cone theory breaks down, for two reasons: the orbits are quasi-Keplerian, and so maintain their orientations for many periods, violating the assumption of randomness; and general relativity begins to become important. |
| Astronomy Colloquium: Michelle Collins | Wed. September 2nd, 2015 11:00 am-12:00 pm |
The faintest galaxies as probes of cosmology and galactic evolution As the faintest galaxies we are able to observe in the Universe, the dwarf spheroidals can be thought of as the fundamental galactic unit. Within our Local Group, we are able to study these objects in extremely high detail, resolving their mass profiles, chemistries, and evolutionary histories. These measurements have led to several surprising results. One is that the masses of these systems appear to be lower than predicted by cold dark matter simulations. Additionally, dwarf galaxies are not distributed isotropically around their hosts, |
| Dynamical Evolution of Very Young Stellar Sub-Cluster | Fri. April 17th, 2015 11:00 am-1:00 pm |
Dynamical Evolution of Very Young Stellar Sub-Clusters Alison Sills, McMaster University Recent observations of massive, young, nearby star-forming complexes are starting to probe the detailed structure of newly-forming star clusters. In particular, the MYStIX collaboration (Feigelson et al. 2013) have an extensive census of stars in 20 such regions, probing down to low masses and through significant interstellar extinction. Early results suggest that most star clusters form from a number of distinct subclusters, and that those subclusters themselves have interesting stellar age and mass distributions. In this talk, I will discuss results from a project to dynamically model very young, Continue reading… Dynamical Evolution of Very Young Stellar Sub-Cluster |
| Stellar Mergers and Interactions: Yes, Virginia, Stars Do Collide | Thu. April 16th, 2015 8:00 pm-10:00 pm |
Stellar Mergers and Interactions: Yes, Virginia, Stars Do Collide Alison Sills, McMaster University Professor Sills will discuss strong interactions between stars in a variety of environments. Despite the vast (average) interstellar distances, stars are social creatures and tend to live in pairs, multiples, or groups. Under these circumstances, stars can, and do, modify each other’s mass, radius, composition, and overall evolution through gravitational encounters ranging from wind mass transfer in a binary system to complete stellar collisions and mergers. She will show how such events can change our understanding of particular stellar systems, how they can explain the properties of many unusual objects, Continue reading… Stellar Mergers and Interactions: Yes, Virginia, Stars Do Collide |
| Adventures in Data Science: An Astronomer Takes the Road Ever-More-Often Traveled By | Wed. April 1st, 2015 11:00 am-1:00 pm |
Adventures in Data Science: An Astronomer Takes the Road Ever-More-Often Traveled By Craig Rudick, University of Kentucky About two years ago I left my Astronomy postdoc position for a job in the “real” world. Since then I’ve been a Data Scientist at the University of Kentucky (in the IT Department on the staff/business side), analyzing UK’s internal data on students, faculty, classes, and other business operations. The first half of my talk will be about career issues: what a data scientist is, how and why I became one, lessons learned from job hunting, transferrable skills for students (and their advisors) to focus on, |
| Interpreting Dwarf Galaxy Observations with Realistic Simulations | Wed. March 18th, 2015 11:00 am-1:00 pm |
Interpreting Dwarf Galaxy Observations with Realistic Simulations Alyson Brooks, Rutgers University The cosmological model based on cold dark matter (CDM) and dark energy has been hugely successful in describing the observed evolution and large scale structure of our Universe. However, at smaller scales, dwarf galaxy observations have long presented a challenge to CDM galaxy formation theory. Recently, high resolution cosmological simulations that include baryonic physics within a CDM context have finally been able to successfully reproduce many of the characteristics of dwarfs, including those characteristics that challenged CDM theory. I will present results from simulations of both isolated and satellite dwarf galaxies, Continue reading… Interpreting Dwarf Galaxy Observations with Realistic Simulations |
| Stars and Galaxies at the Dawn of Time | Thu. March 5th, 2015 8:00 pm-10:00 pm |
Stars and Galaxies at the Dawn of Time Volker Bromm, University of Texas, Austin How and when did the cosmic dark ages end? I will present the remarkable story of how the first stars and galaxies formed, a few hundred million years after the Big Bang. These first sources of light fundamentally transformed the early universe from an initially very simple state to one of ever increasing complexity. Until now, our knowledge of this period of cosmic dawn relies on supercomputer simulations. But over the next decade, a number of new-generation observational facilities, such as the James Webb Space Telescope and the Giant Magellan Telescope, |
| The First Stars and Galaxies: The Run-up to the JWST | Wed. March 4th, 2015 11:00 am-1:00 pm |
The First Stars and Galaxies: The Run-up to the JWST Volker Bromm, University of Texas, Austin How and when did the cosmic dark ages end? I discuss the physics of how the first stars and galaxies formed, within the context of cosmological structure formation. I will address their feedback on the pristine intergalactic medium, and describe ways to probe their signature with next generation facilities. I will identify the key processes and outline the major remaining uncertainties. Continue reading… The First Stars and Galaxies: The Run-up to the JWST |
| What do the smallest galaxies tell us about dark matter? | Wed. February 11th, 2015 11:00 am-1:00 pm |
What do the smallest galaxies tell us about dark matter? Matt Walker, Carnegie Mellon University I will discuss how to translate stellar kinematics observed in the nearest, smallest and and ‘darkest’ galaxies into a test of the standard hypothesis that dark matter consists of ‘cold’ and ‘collisionless’ (i.e., weakly interacting) particles. This model now seems to require that baryon-driven processes (e.g., energetic feedback from supernova explosions) alters the internal structure of galactic dark matter halos systematically with respect to predictions derived from cosmological N-body simulations. I will discuss future work that will let us judge whether such reconciliation is energetically feasible. Continue reading… What do the smallest galaxies tell us about dark matter? |
| Orion as a Laboratory of Protostellar Evolution: Results from the Herschel Orion Protostar Survey | Wed. February 4th, 2015 11:00 am-1:00 pm |
Orion as a Laboratory of Protostellar Evolution: Results from the Herschel Orion Protostar Survey Tom Megeath, University of Toledo The Orion molecular clouds are a remarkable laboratory for studying star formation across the mass spectrum and across the full range of environments in which stars form, from crowded clusters containing massive stars to relatively isolated low mass star formation. I will present results from the Herschel Orion Protostar Survey, or HOPS, a study of over 300 protostar in the Orion clouds with the Herschel, Spitzer, Hubble and APEX telescopes. The goal of this study is to study low to intermediate mass protostars in the Orion molecular clouds (but outside the Orion Nebula) from the earliest phases through the termination of mass infall. |
| Mercury: New views from MESSENGER | Wed. January 21st, 2015 11:00 am-1:00 pm |
Mercury: New views from MESSENGER Steve Hauck, Earth, Environmental, and Planetary Sciences, CWRU More than 35 years after Mariner 10 made its third and final flyby of the planet Mercury MESSENGER (short for MErcury, Surface, Space ENvironment, GEochemistry, and Ranging) became the first spacecraft to orbit the planet in March of 2011. Among the primary goals of the MESSENGER mission are to map its surface, determine the composition of the planet and its exosphere, and to constrain the structure of its interior and the nature of the planetary magnetic field. We will discuss highlights of some of MESSENGER’s major discoveries and talk about the upcoming end of the mission. |
| Probing Cosmic Acceleration with the Dark Energy Survey | Thu. December 11th, 2014 4:00 pm-5:00 pm |
Probing Cosmic Acceleration with the Dark Energy Survey Josh Frieman, University of Chicago / FermiLab The Nobel Prize in Physics for 2011 was awarded for the discovery that the expansion of the Universe is accelerating. Yet the physical origin of cosmic acceleration remains a mystery. The Dark Energy Survey (DES) aims to address the questions: why is the expansion speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If dark energy, is it the energy density of the vacuum (Einstein’s cosmological constant) or something else? Continue reading… Probing Cosmic Acceleration with the Dark Energy Survey |
| Probing the Dark Universe | Thu. December 11th, 2014 8:00 pm-10:00 pm |
Probing the Dark Universe Josh Frieman, University of Chicago / FermiLab Over the last two decades, cosmologists have made a remarkable discovery about our Universe: only 4% is made of ordinary matter—atoms, molecules, etc. The other 96% is dark, in forms unlike anything with which we are familiar. About 25% is dark matter, which holds galaxies and larger‐scale structures together, and may be a new elementary particle. And 70% is thought to be dark energy, which is driving the expansion of the Universe to speed up. This talk will introduce the Dark Universe, overview what we have learned about it, |
| Globular Cluster Streams as Galactic High-Precision Scales | Wed. November 19th, 2014 11:00 am-1:00 pm |
Globular Cluster Streams as Galactic High-Precision Scales Andreas Küpper, Columbia University Tidal streams are promising probes of the gravitational potential of the Milky Way and of the clumsiness of its dark-matter halo. We model the tidal stream of the Milky Way globular cluster Palomar 5 (Pal 5), and show that the unique geometry of the problem yields powerful constraints on the model parameters characterizing the Local Standard of Rest (LSR), the Milky Way and Pal 5 itself. Using only SDSS data and a few radial velocities from the literature, we find that the distance of the Sun from the Galactic Center is 8.30+/-0.25 kpc, Continue reading… Globular Cluster Streams as Galactic High-Precision Scales |
| Directions to the Nearest Alien Earth-like Planet | Thu. November 13th, 2014 8:00 pm-10:00 pm |
Directions to the Nearest Alien Earth-like Planet Sarah Ballard, University of Washington Astronomers used to hedge at the question of whether the Sun and its system of planets are unusual in the cosmos. The study of exoplanets – planets around other stars – is relatively new. State-of- the-art instruments just brush up against the sensitivity to find planets similar to our very own planet Earth. I will summarize findings from the past couple years that contextualize Earth as one potentially habitable, rocky planet among many. However, the environments of these worlds are by-and-large astoundingly different from the conditions that have nourished life here at home. Continue reading… Directions to the Nearest Alien Earth-like Planet |
| Choose Your Own Adventure: Multiplicity of Planets among the Kepler M Dwarfs | Wed. November 12th, 2014 11:00 am-1:00 am |
Choose Your Own Adventure: Multiplicity of Planets among the Kepler M Dwarfs Sarah Ballard, University of Washington The Kepler data set has furnished more than 130 exoplanetary candidates orbiting M dwarf hosts, nearly half of which reside in multiply transiting systems. I investigate the proposition of self-similarity in this sample, first posited by Swift et al. (2013) for the analysis of the five-planet system orbiting the small star Kepler-32. If we compare the predictions of one single mode of planet multiplicity and coplanarity against the Kepler sample, we can test whether we replicate the multi-planet yield of Kepler. Continue reading… Choose Your Own Adventure: Multiplicity of Planets among the Kepler M Dwarfs |
| A Tale of Three Neutrinos | Wed. October 29th, 2014 11:00 am-1:00 am |
A Tale of Three Neutrinos Derek Fox, Penn State University I will discuss recent work to identify the brightest sources of high-energy (e_nu > TeV) neutrinos in the cosmos, those amenable to detection by IceCube, ANTARES, and other high-energy neutrino facilities. In our first tale, a neutrino produced in the high energy-density, high Lorentz-factor outflow of a gamma-ray burst arrives in coincidence with the high-energy photons from that event. While these photons might trigger a burst detection by Swift or another GRB mission, they might alternatively fail to trigger; I will discuss how the Astrophysical Multimessenger Observatory Network under development at Penn State would help to identify these subthreshold coincidences. |
| Do astronomical data contradict the existence of dynamically relevant particle cold or warm dark matter? | Wed. October 8th, 2014 11:00 am-1:00 pm |
Do astronomical data contradict the existence of dynamically relevant particle cold or warm dark matter? Pavel Kroupa, University of Bonn The dual-dwarf-galaxy theorem, according to which two types of galaxies must exist and which must be true in the standard model of cosmology, appears to be ruled by astronomical data: both types of dwarf galaxy, those with putative exotic dark matter and those known to not contain dark matter even if it were to exist, cannot be distinguished by observation. Furthermore, the arrangement of satellite galaxies in rotating disk-like vast near-polar structures around the Milky Way and Andromeda galaxies and the frequent occurrence of anisotropic flattened satellite populations around major galaxies, |
| Lifting the Dusty Veil: Understanding the Stellar Structure of Spiral Disks | Fri. September 26th, 2014 12:30 pm-2:30 pm |
Lifting the Dusty Veil: Understanding the Stellar Structure of Spiral Disks Andrew Schechtman-Rook, University of Wisconsin Measuring the vertical distribution of starlight in spiral galaxies can give valuable insights on both the formation and growth of these complex systems. Unfortunately the study of such structure outside of our Milky Way is significantly hampered by the presence of interstellar dust, which acts to attenuate light in a highly complex manner. The dust is preferentially distributed near the midplane, which makes studying that region extremely difficult. Using a combination of sub-arcsecond resolution near-infrared imaging and advanced radiative transfer modeling we have probed the stellar disk structure of several nearby edge-on spiral galaxies on vertical scales of less than 100 pc. Continue reading… Lifting the Dusty Veil: Understanding the Stellar Structure of Spiral Disks |
| Astrophysics’ Extreme Matter Experiments: Understanding the Diagnostics | Wed. September 17th, 2014 11:00 am-1:00 pm |
Astrophysics’ Extreme Matter Experiments: Understanding the Diagnostics Chris Fryer Los Alamos National Lab Astrophysical Transients (supernovae, gamma-ray bursts, kilanovae, …) are often hailed as ideal laboratories to study matter at high temperatures and nuclear densities. But, as with any experiment, what we can learn about the physics of extreme matter depends both on the quality of the experiment: how well we can constrain the initial conditions and how well we can tie the observed diagnostics back to the physics we wish to study. I will review the wealth of diagnostics astronomers gather in astrophysical transients and discuss how these are used to improve our understanding of extreme states of matter Continue reading… Astrophysics’ Extreme Matter Experiments: Understanding the Diagnostics |
| Testing Galaxy Formation with Clustering Statistics and ΛCDM Halo Models at z=0-1 | Wed. September 10th, 2014 11:00 am-1:00 pm |
Testing Galaxy Formation with Clustering Statistics and ΛCDM Halo Models at z=0-1 Ramin Skibba, UC San Diego Galaxies form and evolve in particular environments of the cosmic web, which consists of a variety of filaments and knots, as well as voids and underdense regions. The influence of a galaxy’s environment on its evolution has been studied and compared extensively in the literature, although differing techniques are often used to define ‘environment.’ I will begin by assessing measures of environmental correlations using mock galaxy catalogs. I will introduce a new method for quantifying environmental correlations, Continue reading… Testing Galaxy Formation with Clustering Statistics and ΛCDM Halo Models at z=0-1 |