We use 10 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf (WD) cooling sequence in the solar-metallicity open cluster NGC 2158. Our photometry and completeness tests show that the end falls at magnitude m F606W = 27.5 ± 0.15, which implies an age between ~1.8 and ~2.0 Gyr, consistent with the age of 1.9 ± 0.2 Gyr obtained from fits to the main-sequence turn-off. The faintest WDs show a clear turn toward bluer colors, as predicted by theoretical isochrones. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under GO-10500.
THE BOTTOM OF THE WHITE DWARF COOLING SEQUENCE IN THE OLD OPEN CLUSTER NGC 2158
BEDIN, LUIGI;PIOTTO, GIAMPAOLO;
2010
Abstract
We use 10 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf (WD) cooling sequence in the solar-metallicity open cluster NGC 2158. Our photometry and completeness tests show that the end falls at magnitude m F606W = 27.5 ± 0.15, which implies an age between ~1.8 and ~2.0 Gyr, consistent with the age of 1.9 ± 0.2 Gyr obtained from fits to the main-sequence turn-off. The faintest WDs show a clear turn toward bluer colors, as predicted by theoretical isochrones. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under GO-10500.Pubblicazioni consigliate
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