Chemically Peculiar Main Sequence Stars

Magnetic Chemically Peculiar Main Sequence Stars 

An important difference between these fields and those observed in late-type stars is that the chemically peculiar star fields show no time dependence. The rotational phase of the dipole remains constant, in some cases over more than 3000 rotation periods (as in CVn), and there is no evidence for changes in the surface distribution of overabundance patches. Thus these fields seem to be a relic from an earlier stage of evolution and not to be continually generated by any dynamo activity. While their frequency 

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Magnetic Chemically Peculiar Main Sequence Stars... 

Abstract Although once it was thought that main-sequence stars are remarkably homogeneous with respect to their chemical composition, the upper main-sequence stars (30000 > Te > 7000) show a variaety of chemically peculiar stars besides the so-called normal stars. Those include the Am, Ap, A Bootis, He-deficient, and He-rich stars. This review summarizes the current data, which are necessary to construct and test the theoretical models of these stars. In the second half of the review we concentrate on Li. In the lower main-sequecnce stars abundances of Li have been determined in hundreds of stars. Some of the remarkable results are ... 

Fig. 3.37. Rough locations of chemically evolved and peculiar stars in the HR diagram. Full lines show the ZAMS with stellar masses indicated and evolutionary tracks for 0.8, 3 and 15 Af , the helium main sequence (0.5 to 1.5 A/ ),...

Preston, G.W. 1974 The chemically peculiar stars of the upper main sequence. ARAA 12, 257. 

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