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dc.contributor.authorVandenBerg, Don A.
dc.contributor.authorBergbusch, Peter A.
dc.contributor.authorFerguson, Jason W.
dc.contributor.authorEdvardsson, Bengt
dc.date.accessioned2014-11-10T15:42:58Z
dc.date.available2014-11-10T15:42:58Z
dc.date.issued2014-10-10
dc.identifier.citationVandenBerg, Don A.; Bergbusch, Peter A.; Ferguson, Jason W.; Edvardsson, Bengt. 2014. Isochrones for old (> 5 GYR) stars and stellar populations. I. models for-2.4 <= [Fe/H] <=+0.6, 0.25 <= Y <= 0.33, and-0.4 <= [alpha/Fe] <=+0.4. The Astrophysical Journal, vol. 794:no. 1:Article no. UNSP 72en_US
dc.identifier.issn0004-637X
dc.identifier.otherWOS:000342581200072
dc.identifier.urihttp://dx.doi.org/10.1088/0004-637X/794/1/72
dc.identifier.urihttp://hdl.handle.net/10057/10874
dc.descriptionClick on the DOI link to access the article (may not be free).en_US
dc.description.abstractCanonical grids of stellar evolutionary sequences have been computed for the helium mass-fraction abundances Y = 0.25, 0.29, and 0.33, and for iron abundances that vary from 2.4 to +0.4 (in 0.2 dex increments) when [alpha/Fe] = +0.4, or for the ranges 2.0 <= [Fe/H] <= +0.6, 1.8 <= [Fe/H] <= +0.6 when [alpha/Fe] = 0.0 and -0.4, respectively. The grids, which consist of tracks for masses from 0.12 M-circle dot to 1.1-1.5 M-circle dot (depending on the metallicity) are based on up-to-date physics, including the gravitational settling of helium (but not metals diffusion). Interpolation software is provided to generate isochrones for arbitrary ages between approximate to 5 and 15 Gyr and any values of Y, [alpha/Fe], and [Fe/H] within the aformentioned ranges. Comparisons of isochrones with published color magnitude diagrams (CMDs) for the open clusters M67 ([Fe/H] approximate to 0.0) and NGC 6791 ([Fe/H] approximate to 0.3) and for four of the metal-poor globular clusters (47 Tuc, M3, M5, and M92) indicate that the models for the observed metallicities do a reasonably good job of reproducing the locations and slopes of the cluster main sequences and giant branches. The same conclusion is reached from a consideration of plots of nearby subdwarfs that have accurate Hipparcos parallaxes and metallicities in the range -2.0 <= [Fe/H] <= -1.0 on various CMDs and on the (log T-eff, M-V) diagram. A relatively hot temperature scale similar to that derived in recent calibrations of the infrared flux method is favored by both the isochrones and the adopted color transformations, which are based on the latest MARCS model atmospheres.en_US
dc.language.isoen_USen_US
dc.publisherIOP Publishingen_US
dc.relation.ispartofseriesThe Astrophysical Journal;v.794:no.1
dc.subjectGlobular clusters: individual (47 Tuc, M3, M5, M92)en_US
dc.subjectOpen clusters and associations: individual (M67, NGC 6791)en_US
dc.subjectStars: abundancesen_US
dc.subjectStars: evolutionen_US
dc.subjectStars: Population IIen_US
dc.titleIsochrones for old (> 5 GYR) stars and stellar populations. I. models for-2.4 <= [Fe/H] <=+0.6, 0.25 <= Y <= 0.33, and-0.4 <= [alpha/Fe] <=+0.4en_US
dc.typeArticleen_US
dc.rights.holderCopyright IOP Publishing, 2014


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