He did his postdoctoral work at the Owens Valley Radio Observatory, California Institute of Technology, and was on the faculty of the Department of Physics at Columbia University.

He is a founding member and Associate Director of the UCLA Galactic Center Group along with Eric Becklin and Andrea Ghez.

[1] The UCLA Galactic Center group uses images from the Keck Observatory to map the orbits of stars bound to the Milky Way's supermassive black hole, enabling a test of general relativity.

[5] He continues to study high energy phenomena in the Galactic Center, including an X-ray fountain,[6] radio structures connected to the central black hole Sgr A*, and star formation, including the detection of one of the most luminous stars in the Milky Way.

[7] His early work included landmark theoretical[8] and observational[9] studies of mass loss in the advanced stages of evolution of red giant stars, including examples of spectacular mass loss in red giants.