399 citations · 8.4k across the 106 of their papers we have counts for
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A Young White Dwarf Companion to Pulsar 1620-26: Evidence for Early Planet Formation
Steinn Sigurdsson, Harvey B. Richer, Brad M. Hansen +2
The pulsar B1620-26 has two companions, one of stellar mass and one of planetary mass. We detected the stellar companion using Hubble Space Telescope observations. The color and ma…
The need for a second black hole at the Galactic center
Brad Hansen, Milos Milosavljevic
Deep infra-red observations and long-term monitoring programs have provided dynamical evidence for a supermassive black hole of mass 3.e6 solar masses associated with the radio sou…
Searching for Variability in the Globular Cluster Messier 4
Robert D. Ferdman, Harvey B. Richer, James Brewer +11
Time-series data taken with the Hubble Space Telescope of a field six core radii (~5') from the center of the globular cluster Messier 4, and covering a period of about 10 weeks in…
The Galactic Inner Halo: Searching for White Dwarfs and Measuring the Fundamental Galactic Constant, Vo/Ro
Jasonjot S. Kalirai, Harvey B. Richer, Brad M. Hansen +9
We establish an extragalactic, zero-motion frame of reference within the deepest optical image of a globular star cluster, an HST 123-orbit exposure of M4 (GO 8679, cycle 9). The l…