Probing the Faintest Stars in a Globular Star Cluster

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dc.creatorRicher, Harvey B.
dc.creatorAnderson, Jay
dc.creatorBrewer, James
dc.creatorDavis, Saul
dc.creatorFahlman, Gregory G.
dc.creatorHansen, Brad M. S.
dc.creatorHurley, Jarrod
dc.creatorKalirai, Jasonjot S.
dc.creatorKing, Ivan R.
dc.creatorReitzel, David
dc.creatorRich, R. Michael
dc.creatorShara, Michael M.
dc.creatorStetson, Peter B.
dc.date2007-02-07
dc.date.accessioned2026-07-07T10:21:45Z
dc.date.available2026-07-07T10:21:45Z
dc.descriptionNGC 6397 is the second closest globular star cluster to the Sun. Using 5 days of time on the Hubble Space Telescope, we have constructed the deepest ever color-magnitude diagram for this cluster. We see a clear truncation in each of its two major stellar sequences. Faint red main sequence stars run out well above our observational limit and near to the theoretical prediction for the lowest mass stars capable of stable hydrogen-burning in their cores. We also see a truncation in the number counts of faint blue stars, namely white dwarfs. This reflects the limit to which the bulk of the white dwarfs can cool over the lifetime of the cluster. There is also a turn towards bluer colors in the least luminous of these objects. This was predicted for the very coolest white dwarfs with hydrogen-rich atmospheres as the formation of H2 causes their atmospheres to become largely opaque to infrared radiation due to collision-induced absorption.
dc.description12 pages, 4 figures. Full Resolution Figures in Science, 2006, 313, 936
dc.identifierhttps://arxiv.org/abs/astro-ph/0702209
dc.identifierhttp://arxiv.org/abs/astro-ph/0702209
dc.identifierScience313:936,2006
dc.identifierdoi:10.1126/science.1130691
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/175277
dc.subjectAstrophysics
dc.titleProbing the Faintest Stars in a Globular Star Cluster
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