August 28, 1995: Peering deep into the globular star cluster M4 with the Hubble telescope, Canadian and American astronomers have discovered a large number of "stellar corpses," called white dwarf stars, which may be used eventually to refine age estimates of the universe.
The observation was so sensitive that even the brightest of the detected white dwarfs was no more luminous than a 100-watt light bulb seen at the moon's distance (239,000 miles). A Hubble color image of a small portion of the cluster reveals eight white dwarf stars [inside the white circles] among the cluster's much brighter population of yellow, Sun-like stars and cooler red dwarf stars. Hubble reveals a total of 75 white dwarfs in one small area within M4 out of a total of about 40,000 white dwarfs that the cluster is predicted to contain. The picture on the left is a view of the cluster taken by a ground-based telescope.See the rest:
Credit: Harvey Richer (University of British Columbia, Vancouver, Canada) and NASA