Are There Any Stars Lacking Neutron-Capture Elements? Evidence from Strontium and Barium

Дата и время публикации : 2012-11-14T21:08:36Z

Авторы публикации и институты :
Ian U. Roederer (Carnegie Observatories)

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: Accepted for publication in the Astronomical Journal (8 pages, 3 figures)
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: The cosmic dispersion in the abundances of the heavy elements strontium and barium in halo stars is well known. Strontium and barium are detected in most cool, metal-poor giants, but are these elements always detectable? To identify stars that could be considered probable candidates for lacking these elements, I examine the stellar abundance data available in the literature for 1148 field stars and 226 stars in dwarf galaxies, 776 of which have metallicities lower than [Fe/H]<-2.0. Strontium or barium have been detected in all field, globular cluster, and dwarf galaxy environments studied. All upper limits are consistent with the lowest detected ratios of [Sr/H] and [Ba/H]. The frequent appearance of these elements raises the intriguing prospect that at least one kind of neutron-capture reaction operates as often as the nucleosynthesis mechanisms that produce lighter elements, like magnesium, calcium, or iron, although the yields of heavy elements may be more variable.

Category: Physics