[Picture of Ghez]

Andrea Ghez

Office: PAB 3-911
Phone: (310)206-0420
ghez at astro.ucla.edu

Educational Background

Current Professional Positions

Curriculum Vitae: Short-version & Long-version (Bio)

Research Interests

Professor Ghez is currently interested in using and developing high spatial resolution imaging techniques to (1) study star formation and (2) investigate the proposed massive black hole at the center of our Galaxy. Owing to turbulence in our atmosphere, the resolution of pictures obtained with traditional imaging techniques from large ground based telescopes is a factor of 10-30 worse than the theoretical limit. Using a variety of interferometric techniques and adaptive optics, Professor Ghez has been able to produce diffraction-limited images of a variety of astronomical objects. With the Keck Telescopes, these images have the highest spatial resolution currently obtainable from the ground or space.

In her studies of star forming regions, she has found that most, if not all, young stars have companion stars and the majority are located at distances that are less than the size our Solar system. This raises a host of interesting questions. What effect do the close companion stars have on the formation of planets around these young stars? How do single stars, such as our Sun, form? What mechanism produces multiple star systems and what can influence their final properties? To address these issues and others, she works at a variety of different telescopes observing sources primarily at infrared wavelengths.

The case for a massive black hole at the center of our Galaxy has been argued over the past few decades, however it has not been previously possible to prove this tantalizing hypothesis. In principle the stars in the vicinity of the Galactic Center can be used as ``test particles" to probe the for the presence of a central dark mass. However, the density of stars in this region is so high that previous studies have reached an impasse due to limitations in angular resolution. With the ability to carry out diffraction-limited imaging at Keck, Prof. Ghez has mapped the Galactic Center with unprecedented angular resolution. These observations reveal stars moving at apparent speed as high as 12,000 km/sec (~4% the speed of light!) whose orbits implies the presence of 3.7 million times that mass of the Sun of dark matter interior to a radius of about 0.0002 pc (6 light hours or 600 Rs). This exceeds volume averaged mass densities inferred for any other galaxy and leads to the conclusion that our Galaxy harbors a massive central black hole. If galaxies as inactive as our own support a central black hole, then one might assume that such objects can be found at the centers of all galaxies! ( more information, pictures & animations )

Selected Publications

Ghez, A. M., Neugebauer, G., & Matthews, K. 1993, AJ, 106, 2005
The Multiplicity of T Tauri Stars in the Taurus-Auriga & Ophiuchus-Scorpius Star Forming Regions: A 2.2 micron Imaging Survey

Ghez, A.M., White, R.J. and Simon, M. 1997, ApJ, 490, 353
High Spatial Resolution Imaging of Pre-Main Sequence Binary Stars: Resolving the Relationship Between Disks and Close Companions

Ghez, A. M., Klein, B. L., Morris, M., and Becklin, E. E. 1998, ApJ, 509 678
High Proper Motions in the Vicinity of Sgr A*: Unambiguos Evidence for a Massive Central Black Hole

White, R.J. & Ghez, A.M. 2001, 556, 265
Observational Constraints on the Formation and Evolution of Binary Stars

Ghez, A.M., Morris, M., Becklin, E.E., Tanner, A.& T. Kremenek, 2000, Nature, 407, 349
The Accelerations of Stars Orbiting the Milk Way's Central Black Hole

Ghez, A.M., Duchene, G., Matthews, K., Hornstein, S. D., Tanner, A., Larkin, J., Morris, M., Becklin, E.E., Salim, S., T. Kremenek, Thompson, D., Soifer, B. T., McLean, I., Neugebauer, G. 2003, ApJ, 586, L127
The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth

Ghez, A.M., Salim, S., Weinberg, N.N., Lu, J.R., Do, T., Dunn, J.K., Matthews, K., Morris, M.R., Yelad, S., Becklin, E.E., Kremenek, T., Molosavljevic, M., Naiman, J. 2008, ApJ, 689, 1044
Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits

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Last modified January 26, 2011