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Abstract: In response to the proposed high helium content stars as an explanation forthe double main sequence observed in Omega Centauri, we investigated theconsequences of such stars elsewhere on the color-magnitude diagram. Weconcentrated on the horizontal branch where the effects of high helium areexpected to show themselves more clearly. In the process, we developed aprocedure for comparing the mass loss suffered by differing stellar populationsin a physically motivated manner. High helium stars in the numbers proposedseem absent from the horizontal branch of Omega Centauri unless their mass losshistory is very different from that of the majority metal-poor stars. It ispossible to generate a double main sequence with existing Omega Centauri starsvia accretion of helium rich pollution consistent with the latest AGB ejectatheoretical yields, and such polluted stars are consistent with the observed HBmorphology of Omega Centauri. Polluted models are consistent with observedmerging of the main sequences as opposed to our models of helium rich stars.Using the B-R-B+V+R statistic, we find that the high helium bMS starsrequire an age difference compared to the rMS stars that is too great, whereasthe pollution scenario stars have no such conflict for inferred Omega Centaurimass losses.



Autor: G. Newsham, D. M. Terndrup Ohio State

Fuente: https://arxiv.org/







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