Frits Paerels got his PhD in the Netherlands, was a postdoc and a researcher at UC Berkeley, and has been at Columbia since 1995. He has been a professor of astronomy since 2001. His interests have centered on high energy astrophysics, and especially on X-ray spectroscopy. Some of the topics he has worked on are the spectroscopy of X-ray binaries, the physics of the interstellar medium and the intergalactic medium, galaxy clusters, and, on and off, the spectroscopy of X-ray emitting neutron stars.
Title: Evidence for Photospheric Absorption Lines in the X-ray Spectrum of the Neutron Star in Puppis A
Abstract: I present evidence for atomic absorption in the photospheric spectrum of RX J0822-4300, the neutron star in Puppis A. The atmosphere is mainly composed of Oxygen and Neon. We see the predicted Zeeman splits and shifts and spectroscopically confirm the previously measured surface magnetic field strength. The gravitational redshift is z = 0.29. We also detect the pressure broadening of the absorption lines; this will allow a spectroscopic measurement of mass and radius of the star.