IAS/PU Joint Astrophysics Colloquium

With current technology, young (<100 Myr) planets can be directly imaged - resolved from their parent star - in the near-infrared with adaptive optics. I will discuss results from such imaging, particularly the four-planet system orbiting HR8799. The outer two planets have been characterized spectroscopically using adaptive optics on the Keck telescope, showing non-equilibrium chemistry as well as evidence of composition enhanced in C/O from the original stellar nebula. The next step in direct imaging is Gemini Planet Imager and its counterparts on other telescopes. GPI is a a facility-class instrument operating on the Gemini South telescope, combining advanced adaptive optics with a coronagraph and near-infrared integral field spectrograph. Almost an order of magnitude more sensitive than current instruments, GPI had first light in November 2013. I will present an overview of the instrument and early science results including the orbit and spectrum of the planet Beta Pictoris b, polarization of the HR4796A circumstellar dust disk, and the status of the 600-star GPI Exoplanet Survey. Finally, I will discuss the potential of the WFIRST/AFTA space telescope for direct exoplanet imaging.

http://www.ias.edu/sns/~seminar/colloquia.shtml

Anomalous X-ray Pulsars and Soft Gamma-Ray Repeaters (SGRs) are young neutron stars characterized by high X-ray quiescent luminosities, outbursts, and, in the case of SGRs, sporadic giant flares. They are believed to be magnetars, that is neutron...

Saturn’s satellite Enceladus displays a bewildering array of thermal activity. I will describe our attempts to understand these phenomena in terms of tidal heating associated with the 2:1 mean motion resonance between Enceladus and Dione. Then I...

I review the physics of launching, acceleration, and propagation of radiation driven winds. I will consider two kinds of outflows powered by radiation emitted from the AGN central engine: (1) outflows driven from the innermost part of a black hole...

Explorations of the radio sky in the time-domain are an exciting frontier in astrophysics, and one where new observational capabilities will open up new windows on the universe. As one of a new generation of widefield, low-frequency radio telescopes...

The first light of a core-collapse supernova emerges the moment a shock front breaches the stellar photosphere — just after the star has been engulfed by its explosion, and just before it releases its fastest ejecta. Shock emergence is implicated in...

ABSTRACT: The IceCube Neutrino Observatory has recently discovered a diffuse flux of astrophysical neutrinos, neutrinos from beyond the solar system. But how does one collect neutrinos at the South Pole? Why study neutrinos for astronomy? In this...

Deviations from a uniformly expanding universe are of interest in modern cosmology, most particularly because the amplitude of such peculiar motions measures the strength of gravity on scales of roughly 10-100 Mpc. I will review various recent...

After 50 years of dreaming about it, space-based microlensing observations are now underway. A 2014 100-hr Spitzer Pilot Program generated "microlens parallaxes" for dozens of lenses, opening the prospect of measuring the Galactic distribution of...

A combination of sub-mm observations and numerical simulations have the potential to yield direct constraints on the environment of planet formation. After a review of recent observational surprises, I will discuss the implications of our first...