Credit: Kitt Peak National Observatory 0.9-meter telescope, National Optical Astronomy Observatories; courtesy M. Bolte (University of California, Santa Cruz)
[Right] - A HST color image of a small portion of the cluster only 0.63 light-years across reveals 8 white dwarf stars (inside blue 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 the total of about 40,000 white dwarfs that the cluster is predicted to contain. The Hubble results will allow astronomers to refine theoretical predictions of the rate at which white dwarfs cool -- an important prerequisite for making reliable estimates for the age of the universe and of our Milky Way galaxy, based on white dwarf temperatures. The image was taken with the Wide Field and Planetary Camera 2.
Credit: Harvey Richer (University of British Columbia, Vancouver, Canada) and NASA
Last Modification: 9 May 1998, 17:30 MET