Astronomy 381S - Spring 2014
Seminar in Theoretical Astrophysics
M 3:30 · RLM 15.216B · Not for credit Spring 2014
Date
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Speaker
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Title
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Jan 13
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Milos Milosavljevic
University of Texas at Austin
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Organizational meeting.
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Jan 20
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Martin Luther King, Jr. Holiday: University closed. No talks scheduled.
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Jan 27
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An Astronomy Faculty Meeting is being held at this time. Scheduled Astro Theory talks are being postponed until next week.
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Feb 3
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Chalence Safranek-Shrader
University of Texas at Austin
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"Formation of the First Low-Mass Stars from Cosmological Initial Conditions"
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Feb 3
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Milos Milosavljevic
University of Texas at Austin
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Journal Club: "Primordial Supermassive Stars and Convection in RGB and AGB Atmospheres"
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Feb 10
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No talk scheduled.
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Feb 17
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Alan Sluder
University of Texas at Austin
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"The Role of Population III Supernovae in Galactic Chemical Evolution"
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Feb 24
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Wenbin Lu
University of Texas at Austin
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"Are There Very Massive (Maybe Pop-III) Stars Around a GRB Progenitor?"
abstract
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Mar 3
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Chiara Ceccobello
University of Amsterdam, Netherlands
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(host: Pawan Kumar) "Inverse-Compton drag of a Highly Magnetized GRB jet in Stellar Envelope"
The collimation and evolution of relativistic outflows in gamma-ray bursts
(GRBs) are determined by their interaction with the stellar envelope through
which they propagate before reaching the distance where energy is dissipated
and gamma-rays are produced.
We consider the case of a Poynting flux dominated relativistic outflow
and show that it suffers strong IC scattering drag near
the stellar surface and the outer parts of the jet are slowed down to
sub-relativistic speed especially if its initial magnetization parameter is between 10^3 and 10^6.
However, if the temperature of the cocoon surrounding the jet were to be
larger than about 10 keV, and the magnetization is larger than 10^7, then an optically thick
layer of electrons and positrons forms at the interface of the cocoon and
the jet, and this pair screen protects the interior of the jet from IC drag.
Pairs in the screen annihilate when the jet emerges above the stellar surface
giving rise to a brief pulse of about 100 MeV radiation.
close
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Mar 10
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Spring Break: March 10-14. No talk scheduled.
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Mar 17
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No talk scheduled.
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Mar 24
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Thomas B. McCord
Bear Fight Institute (BFI)
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Special Planets/Life/ISM Seminar: (host: Bill Cochran) "The Composition of Vesta and Ceres from the Dawn Mission"
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Mar 31
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Christa Gall
Dark Center, Copenhagen
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(host: Volker Bromm) "Dust in the Early Universe: Overview"
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Apr 7
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No talk scheduled.
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Apr 14
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Krista Soderlund
UT Institute of Geophysics
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(Joint Seminar in Theory/ISM/Planets) "Convective Dynamics in the Interiors of Ice Giants and Icy Satellites"
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Apr 21
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No talk scheduled.
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Apr 28
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No talk scheduled.
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