17
October 2002
Milky Way: Central casting
Evidence from stellar velocities suggests there is a black hole at the centre of the Milky Way, but the possibility remained that some other large body might have similar effects. Now the analysis of ten years of imaging of the star closest to radio source Sgr A*, pinpointed as the centre of the Galaxy, has allowed its orbit around Sgr A* to be determined. An orbital period of 15.2 years, and close approach of 17 light hours, point to the presence of a tiny central body 3.7 million times the mass of the Sun. This is 'supermassive' black hole territory. Alternatives such as clusters of dark matter cannot match those specifications.
A star in a 15.2-year orbit around the supermassive
black hole at the centre of the Milky Way
R. SCH�DEL,
T. OTT, R. GENZEL, R. HOFMANN, M. LEHNERT, A. ECKART, N. MOUAWAD, T. ALEXANDER,
M. J. REID, R. LENZEN, M. HARTUNG, F. LACOMBE, D. ROUAN, E. GENDRON, G. ROUSSET,
A.-M. LAGRANGE, W. BRANDNER, N. AGEORGES, C. LIDMAN, A. F. M. MOORWOOD, J. SPYROMILIO,
N. HUBIN & K. M. MENTEN
Nature 419, 694–696 (2002);
doi:10.1038/nature01121
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Astronomy: Into the heart of darkness
KARL
GEBHARDT
The Milky Way, like other galaxies, is thought to harbour a black
hole at its centre. The remarkable observation of a star in close orbit around
the Galactic Centre is the first firm evidence that this is so.
Nature
419, 675–676 (2002); doi:10.1038/419675a
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