HST Image of a Galaxy's Nucleus
This Hubble Space Telescope view of galaxy NGC 7457, was taken on August 17, 1990 with the Wide Field/Planetary Camera. The picture on the left with high contrast shows the central portion of the galaxy. Predictably, the density of the starry population smoothly increases toward the galactic center.
The picture on the right is of the same galaxy, but the contrast has been adjusted to reveal a surprisingly high concentration of stars pinpointed exactly at the galaxy's core. The nucleus is so compact it is even beyond HST's 0.1 arcsecond resolution. Stars are crammed together at least 30,000 times more densely than they are in our own stellar neighborhood. It is not yet known how this tight core is gravitationally held together.
Forty million light-years away, NGC 7457 is one of the first "normal" galaxies that HST has observed. This unexpected finding suggests that the cores of many galaxies may be far more densely packed with stars than earlier thought.