Astronomy 160

This semester I’m the GSI for Astro 160: Stellar Physics. This is an upper division undergraduate course being taught by Prof. Eliot Quataert.

Here’s the course description:

Stars are the building blocks of galaxies and play a central role in the evolution of structure in the universe, in the nucleosynthesis of most elements, in the formation of compact objects (white dwarfs, neutron stars, and black holes), and as tools for measuring cosmological distances (e.g., Cepheids and Type 1a SN).  This course will cover the observations and physics of stars. Primary topics will include the structure of self-gravitating objects, energy transport in stars, nuclear fusion in stars, stellar evolution, the birth of compact objects, and stellar oscillations.

Further Evidence for the Bimodal Distribution of Neutron-star Masses

The Astrophysical Journal, Volume 719, Issue 1, pp. 722-727 (2010)

Josiah Schwab, Philipp Podsiadlowski and Saul Rappaport

We use a collection of 14 well-measured neutron-star masses to strengthen the case that a substantial fraction of these neutron stars were formed via electron-capture (e-capture) supernovae (SNe) as opposed to Fe core-collapse SNe. The e-capture SNe are characterized by lower resultant gravitational masses and smaller natal kicks, leading to lower orbital eccentricities when the e-capture SN has led to the formation of the second neutron star in a binary system. Based on the measured masses and eccentricities, we identify four neutron stars, which have a mean post-collapse gravitational mass of ~1.25 M sun, as the product of e-capture SNe. We associate the remaining 10 neutron stars, which have a mean mass of ~1.35 M sun, with Fe core-collapse SNe. If the e-capture SN occurs during the formation of the first neutron star, then this should substantially increase the formation probability for double neutron stars, given that more systems will remain bound with the smaller kicks. However, this does not appear to be the case for any of the observed systems and we discuss possible reasons for this.

Outstanding GSI Award

I was selected as one of the recipients of the 2009-2010 Outstanding Graduate Student Instructor Award in recognition of excellence in teaching in the Physics Department.

Physics 8B

This semester I’m one of the GSIs for Physics 8B: Introductory Physics.  This is an undergraduate course for non-majors being taught by Profs. Mike DeWeese and Catherine Bordel.

Here’s the course description:

Introduction to electricity, magnetism, electromagnetic waves, optics, and modern physics. The course presents concepts and methodologies for understanding physical phenomena, and is particularly useful preparation for upper division study in biology and architecture.