The Age of the Oldest Stars from the Faint End Slope of the White Dwarf LF in Globular Clusters
نویسندگان
چکیده
We propose to determine the absolute magnitude of the end of the white dwarf cooling sequence in the nearest globular clusters. Cooling models of white dwarfs predict ∼ 1 mag difference between an age of 10 and 15 Gyr. The end of the disk cooling sequence is known to occur at Mbol = +17; in the nearest globular clusters, this would be at H=30-31, reachable in a 30 hour exposure. Since the faintest WD are both red and faint, the infrared imaging capability of NGST is ideal for this task. Diffracted light from relatively bright (20th mag) main sequence stars must be controlled. This experiment would be the first measurement of the ages of the oldest stars that is independent of the main sequence turnoff and stellar evolution theory. ASWG DRM Proposal The Age of the Oldest Stars from the Faint End Slope of the White Dwarf LF in Globular Clusters Observing Summary: Target RA Dec KAB Configuration/mode Days NGC 6752 19 10 -59 58 32.0 NIR/CAM R10 6 NGC 104 00 24 -72 04 32.0 NIR/CAM R10 6 NGC 6397 17 40 -53 40 32.0 NIR/CAM R10 6
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