Epoch J2000.0 Equinox J2000.0 (ICRS)
|Right ascension||17h 45m 39.73s|
|Declination||−29° 00′ 29.7″|
GCIRS 13E was first identified as GCIRS 13, which was later resolved into two components GCIRS13E and W. GCIRS 13E was initially modelled as a single object, possibly a binary system. It was even classified as a Wolf-Rayet star because of its strong emission line spectrum, and named WR 101f. It was then resolved into seven Wolf-Rayet and class O stars. The highest-resolution infrared imaging and spectroscopy can now identify 19 objects in GCIRS 13E, of which 15 are dense gaseous regions. The remaining four objects are stars: WN8 and WC9 Wolf-Rayet stars; an OB supergiant; and a K3 giant.
The motions of the members of GCIRS 13E appear to indicate a much higher mass than can be accounted for by the visible objects. It has been proposed that there may be an intermediate-mass black hole with a mass of about 1,300 M☉ at its centre. There are a number of problems with this theory. However, the true nature of the cluster remains unknown.
GCIRS 13E is a small cluster dominated by a few massive stars. It is thought that massive stars cannot form so close to a supermassive black hole and since such massive stars have a short lifespan it is thought that GCIRS 13E must have migrated inward toward the central black hole within the past 10 million years, probably from about 60 light-years further out than its current orbit. The stars are possibly the remains of a globular cluster where a middleweight black hole such as could develop through runaway star collisions.
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