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Tomorrow's CfA Theory Seminar

Andrea Ghez (UCLA)

Title: New Results from the Galactic Center

Preliminary Abstract:

Recent measurements of the velocities of stars near the center of the
Milky Way have  provided the strongest evidence for  the presence of a
supermassive black   hole   in  a   galaxy,  but   the   observational
uncertainties poorly constrain   many of the  properties  of the black
hole. Determining the  accelerations of stars  in their  orbits around
the center provides much  more precise information about the  position
and  mass of  the  black hole.   Here  we report  measurements  of the
accelerations for three stars located ~0.005 pc from the central radio
source Sgr A*; these accelerations are comparable to those experienced
by the Earth  as it orbits  the Sun. These  data increase the inferred
minimum mass density  in the central region  of the Galaxy by an order
of magnitude relative to previous  results and localized the dark mass
to within 0.05  +- 0.04 arcsec of the  nominal position of Sgr A*.  In
addition, the orbital period of one of the  observed stars could be as
short as 15 years,  allowing us the opportunity in  the near future to
observe an entire period.

The seminar will be held in Pratt Conference Room (G04) at 12:30pm
at the CfA.