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The Central Dark Mass of the Milky Way

Published online by Cambridge University Press:  13 May 2016

A. Eckart ,
R. Genzel  and
T. Ott
A. Eckart
Affiliation:
I. Physikalisches Institut, Universität zu Köln, Zülpicherstraße 77, 50937 Köln, Germany
R. Genzel
Affiliation:
MPE, Garching, Postfach 1312, 85741 Garching, Germany
T. Ott
Affiliation:
MPE, Garching, Postfach 1312, 85741 Garching, Germany

Abstract

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Measurements of the proper motions and radial velocities of stars in the central cluster of the Milky Way have revealed the presence of a 2-3 million solar mass black hole at the position of the compact radio source Sagittarius A* (SgrA*). The overall stellar motions do not deviate strongly from isotropy and are consistent with a spherical isothermal stellar cluster. Speckle spectroscopy with SHARP at the NTT and slit spectroscopy with ISAAC at the VLT suggests that several of them are early type stars. This is consistent with the idea that these stars are members of an early type cluster with small angular momentum and therefore are now in the immediate vicinity of SgrA*. Most recent data now allows to measure the curvatures of the stellar orbits for a few of the stars that are closest to the center and have the largest proper motions of up to 1400 km/s. The curvatures indicate that the stars indeed orbit the central compact object and will allow to further determine its mass and compactness.

Type
The Inner Regions of Galaxies
Information
Symposium - International Astronomical Union , Volume 205: Galaxies and their Constituents at the Highest Angular Resolutions , 2001 , pp. 20 - 27
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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