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November 20, 1995
At the Core of M15
(UCO/Lick Observatory, UC Santa Cruz)
Densely packed stars in the core of the globular cluster
M15 are shown
in this Hubble Space Telescope (HST)
image taken in April of 1994. The
stars revealed are contained in an area 1.6 light years across and
their colours roughly indicate their temperatures - hot stars
appear blue, cooler stars look reddish-orange. M15 has long been
recognized as one of the densest cluster of stars in our galaxy outside of
the galactic centre itself.
Even the unprecedented resolving
power of the HST cameras could not separate the individual stars in its
innermost regions. However,
this HST image reveals that the density of stars continues
to rise toward the cluster's core, suggesting that a sudden,
runaway collapse due to the gravitational attraction of many closely
packed stars or a single central massive object, perhaps a
could account for the core's extreme density.
Tomorrow's picture: M42: Orion Nebula Mosaic
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