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http://hdl.handle.net/2248/2135
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DC Field | Value | Language |
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dc.contributor.author | Maas, T | - |
dc.contributor.author | Giridhar, S | - |
dc.contributor.author | Lambert, D. L | - |
dc.date.accessioned | 2008-03-06T07:35:38Z | - |
dc.date.available | 2008-03-06T07:35:38Z | - |
dc.date.issued | 2007-09 | - |
dc.identifier.citation | The Astrophysical Journal, Vol. 666, pp. 378 – 392 | en |
dc.identifier.uri | http://hdl.handle.net/2248/2135 | - |
dc.description.abstract | Abundance analyses from high-resolution optical spectra are presented for 19 type II Cepheids in the Galactic field. The sample includes both short-period (BL Her) and long-period (W Vir) stars. This is the first extensive abundance analysis of these variables. The C, N, and O abundances with similar spreads for the BL Her and W Vir show evidence for an atmosphere contaminated with 3α process and CN-cycling products. A notable anomaly of the BL Her stars is an overabundance of Na by a factor of about 5 relative to their presumed initial abundances. This overabundance is not seen in the W Vir stars. The abundance anomalies running from mild to extreme in W Vir stars but not seen in the BL Her stars are attributed to dust-gas separation that provides an atmosphere deficient in elements of high condensation temperature, notably, Al, Ca, Sc, Ti, and s-process elements. Such anomalies have previously been seen among RV Tau stars which represent a long-period extension of the variability enjoyed by the type II Cepheids. Comments are offered on how the contrasting abundance anomalies of BL Her and W Vir stars may be explained in terms of the stars’ evolution from the blue horizontal branch. | en |
dc.format.extent | 538279 bytes | - |
dc.format.mimetype | application/pdf | - |
dc.language.iso | en | en |
dc.publisher | University of Chicago Press | en |
dc.relation.uri | http://www.journals.uchicago.edu/doi/abs/10.1086/520081 | en |
dc.relation.uri | http://arxiv.org/abs/0706.2029 | en |
dc.subject | stars: abundances—stars: variables | en |
dc.title | The Chemical Compositions of the Type II Cepheids-The BL Herculis and W Virginis Variables | en |
dc.type | Article | en |
Appears in Collections: | IIAP Publications |
Files in This Item:
File | Description | Size | Format | |
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Giridhar.pdf | 525.66 kB | Adobe PDF | ![]() View/Open |
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