Events Archive

The Hydrodynamics of Common Envelope Episodes and the Formation of Close Neutron Star Binaries

Mon, Sep 28, 2015 at 12:00 pm

131A Campbell Hall

Morgan Macleod (UCSC)

A dynamic and crucial phase in the evolution of a binary star system comes when one star engulfs its companion in a shared gaseous envelope. The two stellar cores spiral tighter in response to drag forces. Eventually, they may deposit enough energy and momentum to expel the envelope, leaving behind a binary transformed by orbital tightening and mass accretion. This talk explores the …

More about The Hydrodynamics of Common Envelope Episodes and the Formation of Close Neutron Star Binaries

New Constraints on Cosmic Reionization from Planck and Hubble Space Telescope

Thu, Sep 24, 2015 at 4:00 pm

1 LeConte Hall

Brant Robertson (UCSC)

Understanding cosmic reionization requires the identification and characterization of early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign acquired the deepest blank-field infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic …

More about New Constraints on Cosmic Reionization from Planck and Hubble Space Telescope

Department Lunch Talk 9-24

Thu, Sep 24, 2015 at 12:30 pm

131A Campbell Hall

Dick McCray (UCB) - "Mapping the reverse shock in SN1987A" Vikram Ravi (Caltech) - "Pulsar timing limit on gravitational waves necessitates re-think of binary supermassive black hole evolution" Brant Robertson (UCSC [colloq. spkr.]) - “A New Model for Understanding Supersonic Turbulence”.

More about Department Lunch Talk 9-24

The nature of resolved structures in protoplanetary disks

Wed, Sep 23, 2015 at 3:00 pm

131A Campbell Hall

Robin Dong (UC Berkeley)

In the past few years, direct imaging at near-infrared (NIR) wavelengths and interferometric observations at millimeter wavelengths have revealed a panoply of fine structures in gaseous protoplanetary disks, such as spiral arms, gaps, streamers, and azimuthal asymmetries. The origins of these features are unknown at the moment, although many of them are widely speculated to be created by …

More about The nature of resolved structures in protoplanetary disks

Large Opacity Variations in the z~5.5 Lyman-alpha Forest: Implications for Cosmic Reionization

Tue, Sep 22, 2015 at 1:00 pm

131A Campbell Hall

Anson D’Aloisio (Washington)

When the first galaxies emerged, ~100 - 500 million years after the Big Bang, their starlight reionized and heated the intergalactic hydrogen that had existed since cosmological recombination. Much is currently unknown about this process, including what spatial structure it had, when it started and completed, and even which sources drove it. Recent observations of high-redshift quasars show …

More about Large Opacity Variations in the z~5.5 Lyman-alpha Forest: Implications for Cosmic Reionization

Molecular Gas and the Evolutionary Connection Between Submillimeter Galaxies and AGN at z~2-3

Mon, Sep 21, 2015 at 3:00 pm

131A Campbell Hall

Chelsea Sharon (Cornell)

Theoretical work has suggested that active galactic nuclei (AGN) play an important role in quenching star formation in massive galaxies. Direct evidence for AGN affecting the molecular ISM (the gas phase that fuels star formation) has so far been limited to detections of molecular outflows in low-redshift systems and extreme excitation regions which represent a tiny fraction of the total gas. …

More about Molecular Gas and the Evolutionary Connection Between Submillimeter Galaxies and AGN at z~2-3

What Peculiar Transients Can Teach Us About Stellar Evolution and Stellar Death

Mon, Sep 21, 2015 at 12:00 pm

131A Campbell Hall

Maria Drout (Harvard Cfa)

Multi-wavelength observations of supernovae not only probe the explosion mechanism, but also carry information about the configuration of the star at the moment of collapse and the mass-loss history of the progenitor system in the years immediately preceding its death. The study of supernovae therefore offers us one of our only observational views of the final stages of stellar evolution. As a …

More about What Peculiar Transients Can Teach Us About Stellar Evolution and Stellar Death

All Planets Great and Small

Thu, Sep 17, 2015 at 4:00 pm

1 LeConte

Rebekah Dawson, UC Berkeley

Discoveries of exoplanets so different from those in our Solar System have called in question conventional theories for how planetary systems form and evolve. I will present recent progress in our understanding of the physical processes that drive the assembly of planetary systems and result in the surprising variety of orbital architectures we observe today. I will …

More about All Planets Great and Small

Department Lunch Talk 9-17

Thu, Sep 17, 2015 at 12:30 pm

131A Campbell Hall

Jonathan Zrake (Stanford)
Philipp Moesta (UCB)
Bekki Dawson (UCB - colloq. spkr.)

Jonathan Zrake (Stanford) - "Fast magnetic free energy discharge by turbulence in force-free electrodynamics". Philipp Moesta (UCB) - "MHD-driven Supernovae in Three Dimensions" Bekki  Dawson (UCB - colloq. spkr.) - “The stellar activity problem for exoplanets”

More about Department Lunch Talk 9-17

Paths, Roadblocks, and Byways in Detecting Habitable Rocky Planets in Radial Velocity Data

Wed, Sep 16, 2015 at 3:00 pm

131A Campbell Hall

Sharon Wang (PSU)

The synergy between Kepler and the ground-based radial velocity (RV) surveys have made numerous discoveries of low-mass exoplanets, opening the age of Earth analogs. However, Earth analogs such as Kepler 452-b require a much higher RV precision ( ~ 10 cm/s) than the achievable with current instruments (~ 1 m/s) and understanding of stellar photosphere. I will talk about instrumental and data …

More about Paths, Roadblocks, and Byways in Detecting Habitable Rocky Planets in Radial Velocity Data

Theoretical approaches for studying the epoch of reionization and Dark Matter annihilation

Tue, Sep 15, 2015 at 1:00 pm

131A Campbell Hall

Alex Kaurov (Chicago)

We explore the properties of the intergalactic medium (IGM) during the epoch of reionization numerically. Our simulation models fully self-consistently all relevant physics, from radiative transfer to gas dynamics and star formation, in volumes of up to 40 co-moving Mpc, and with spatial resolution approaching 100 pc in physical units. The achieved resolution allows us to consider the IGM to …

More about Theoretical approaches for studying the epoch of reionization and Dark Matter annihilation

Cooling, AGN Feedback and Star Formation in Simulated Cool-Core Galaxy Clusters

Mon, Sep 14, 2015 at 12:00 pm

131A Campbell Hall

Yuan Li (University of Michigan)

The feedback from active galactic nuclei (AGNs) is widely considered to be the major heating source in cool-core galaxy clusters, preventing a classical cooling flow where the intra-cluster medium (ICM) cools at hundreds to a thousand solar masses per year. Numerical simulations with AGN feedback have successfully suppressed radiative cooling, but generally fail to reproduce the right amount …

More about Cooling, AGN Feedback and Star Formation in Simulated Cool-Core Galaxy Clusters

The Assembly of MASSIVE Elliptical Galaxies

Thu, Sep 10, 2015 at 4:00 pm

1 LeConte

Jenny Greene (Princeton)

Elliptical galaxies comprise the most massive galaxies in the universe today, but their assembly history remains a mystery. I study present-day elliptical galaxies in detail, including their surface brightness profiles, steller population gradients, angular momentum profiles, and gas content, to understand the roles or merging, gas accretion, and black hole growth on the …

More about The Assembly of MASSIVE Elliptical Galaxies

Department Lunch Talk 9-10

Thu, Sep 10, 2015 at 12:30 pm

131A Campbell Hall

Lauren Weiss, UCB
Melissa Graham, UCB
Jenny Greene, Princeton & UCB [Miller Professor, colloq. spkr.]

The Department Lunch Talk series is a weekly event that features three 20 minute talks presented mainly by local scientists of any level to present their work to a broad spectrum of the department and usually includes one short talk by the astronomy colloquium speaker of the day.  Subjects can include personal scientific research, reporting on other work appearing in journals, education and public outreach efforts, science policy, and professional development issues.

More about Department Lunch Talk 9-10

Composition and distribution of clouds in hot Jupiters atmospheres

Wed, Sep 9, 2015 at 3:00 pm

131A Campbell Hall

Vivien Parmentier (UCSC)

Over a large range of equilibrium temperatures clouds seem to dominate the transmission spectrum of hot Jupiters atmospheres but no trend allowing the classification of these objects have yet emerged. Recently observations of the light reflected by these planets provided insight on the cloud distribution on the dayside of these planets : for a handful of planets clouds seem more …

More about Composition and distribution of clouds in hot Jupiters atmospheres