Apr 24 2002
From The Space Library
Scientists announced an estimate of the universe's age based on new HST images of very faint white dwarf stars in Messier 4 (M4), a cluster of stars in the constellation Scorpius. The researchers had closely examined M4's white dwarf stars~ low-mass stars that have exhausted their fuel sources for thermonuclear fusion. Although white dwarfs cool at a predictable rate, enabling scientists to estimate their age, they become progressively fainter as they cool, making them difficult to observe. The HST had provided the first deep exposures of these dim stars, which the astronomers discovered were M4's oldest white dwarf stars, at around 12 to 13 billion years old. Earlier Hubble observations had revealed that the first stars in the universe had formed less than 1 billion years after the universe's emergence from the Big Bang. Thus, the researchers had discovered that the age of these M4 white dwarfs supported the previous estimates that the universe's age is 13 to 14 billion years old. The use of this new methodology to estimate the universe's age represented a major departure from those used previously. (NASA, “Hubble Uncovers Oldest 'Clocks' in Space To Read Age of Universe,” news release 02-73, 24 April 2004; Brad M. S. Hansen et al., “The White Dwarf Cooling Sequence of the Globular Cluster Messier 4,” Astrophysical Journal 574, no. 2 (1 August 2002): L155-L158.)
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