Blue Horizontal--Branch Stars: The "Jump" in Stromgren u, Low Gravities, and Radiative Levitation of Metals

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dc.creatorGrundahl, F.
dc.creatorCatelan, M.
dc.creatorLandsman, W. B.
dc.creatorStetson, P. B.
dc.creatorAndersen, M. I.
dc.creator.
dc.date1999-09-27
dc.date.accessioned2026-07-07T02:33:30Z
dc.date.available2026-07-07T02:33:30Z
dc.descriptionWe study the ``jump'' in the blue horizontal--branch (BHB) distribution first detected by Grundahl et al. (1998) in the Galactic globular cluster (GC) M13. On the basis of Stromgren photometry for a sample of fourteen GC's we show that: 1) The jump is best characterized as a systematic shift, on a (u, u-y) color-magnitude diagram, from canonical zero-age HB (ZAHB) models, in the sense that the stars appear brighter and/or hotter than the models; 2) the jump is a ubiquitous phenomenon, ocurring over the temperature range 11,500 < Teff < 20,000K; 3) An analogous feature is present in (log g, log Teff) diagrams -- indicating a common physical origin for the two phenomena; 4) The physical mechanism responsible for the jump phenomenon is most likely radiative levitation of iron and other
dc.description6 pages, 3 figures, to appear in the proceedings of: "The Galactic Halo: from Globular Clusters to Field Stars"; 35'th Liege Int. Astroph. Coll., 1999
dc.identifierhttps://arxiv.org/abs/astro-ph/9909448
dc.identifierhttp://arxiv.org/abs/astro-ph/9909448
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/14867
dc.subjectAstrophysics
dc.titleBlue Horizontal--Branch Stars: The "Jump" in Stromgren u, Low Gravities, and Radiative Levitation of Metals
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