Open Cluster NGC 6791 15 Oz Stainless Steel Travel Mug
"In studying the dimmest burned-out stars in globular star cluster NGC 6791, NASA's Hubble Space Telescope has uncovered a paradox: three different populations of stars exist in an object where all the stars should have formed at the same time out of an interstellar cloud of gas and dust.
...Two of the populations are burned-out stars called white dwarfs. One group of these low-wattage stellar remnants (red circles) appears to be 6 billion years old, another (blue circles) appears to be 4 billion years old. The ages are out of sync with those of the cluster's normal stars, which are 8 billion years old."