Andrea M. Ghez measures stellar orbits around the supermassive black hole at the center of the Milky Way. Her team's Keck observations combined astrometry with radial velocities for the short-period star S0-2.
An angular orbit alone leaves a mass-distance degeneracy of an angular stellar orbit. Adding Doppler spectroscopy supplies a physical velocity scale, allowing central mass and Euclidean distance to be fitted together. Their 2008 analysis inferred roughly four million solar masses at a Euclidean distance of eight kiloparsecs, and examined how source confusion and assumptions about central motion affected the result.[ref]
Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits by Andrea M. Ghez and others. Abstract: Keck astrometry and radial velocities, unconstrained orbit and identified systematic limitations
Portrait of Andrea M. Ghez
. International Gemini Observatory/NOIRLab/NSF/AURA; still from Feeling gravity’s pull, a video by Julie Winokur. CC BY 4.0, via Wikimedia Commons. Source. Articles by others on the same topic
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Andrea M. Ghez is an American astronomer and professor known for her groundbreaking work in the field of astrophysics, particularly in the study of the supermassive black hole at the center of our galaxy, the Milky Way. She was awarded the Nobel Prize in Physics in 2020, sharing the honor with Reinhard Genzel for their collective discovery of the black hole, which is located in the region known as Sagittarius A*. Ghez is the Lauren B.