Astrophysics

Stars in nearly all globular clusters show complex relations among the abundances of light elements (up to Na).  Many also show anti-correlations of Mg and Al.  Until now, only one cluster (M15) conclusively showed any star-to-star variation in...

Abstract: A perturbed black hole rings down by producing radiation at certain fixed (complex) frequencies - the quasinormal frequencies. These frequencies can be identified with the spectrum of a non-self adjoint operator derived from the evolution...

Each week, we hold a relatively informal seminar/discussion series with an emphasis on extra-galactic and large-scale structure astrophysics.

During Galread a leader/visitor presents a recent paper to the discussion group. The PDF of the paper is...

Abstract 1. The Subaru Prime Focus Spectrograph (PFS) will soon be the first massively-multiplexed wide-field spectrograph on a 8-meter class telescope. PFS’s spectrograph system covers the optical to near-infrared—380 to 1260nm—in a single exposure...

Accretion-powered X-ray Pulsars (XRPs) are strongly magnetized neutron stars (NSs), that accrete matter from a donor companion star, often exhibiting a cyclotron resonant scattering feature (CRSF) in their X-ray spectra. Accretion onto their...

TBA

Intrigued by the recent Thirty Meter Telescope protests on Mauna Kea in Hawai‘i, I launched on a historical study of how astronomy came to the mountain, based on the observatories’ own archives, most of which had never been studied. These documents...

The Milky Way contains of order 10^8 stellar-mass black holes (BHs). Yet, fewer than 100 BH candidates are known, and only about 20 are dynamically confirmed. Our view of the BH population has been shaped almost entirely by observations of X-ray...