English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

It is unknown whether or not low-mass stars can form at low metallicity.While theoretical simulations of Population III (Pop III) star formation showthat protostellar disks can fragment, it is impossible for those simulations todiscern if those fragments survive as low-mass stars. We report the discoveryof a low-mass star on a circular orbit with orbital period P = 34.757 +/- 0.010days in the ultra metal-poor (UMP) single-lined spectroscopic binary system2MASS J18082002--5104378. The secondary star 2MASS J18082002--5104378 B has amass M_2 = 0.14_{-0.01}^{+0.06} M_Sun, placing it near the hydrogen-burninglimit for its composition. The 2MASS J18082002--5104378 system is on a thindisk orbit as well, making it the most metal-poor thin disk star system by aconsiderable margin. The discovery of 2MASS J18082002--5104378 B confirms theexistence of low-mass UMP stars and its short orbital period shows thatfragmentation in metal-poor protostellar disks can lead to the formation andsurvival of low-mass stars. We use scaling relations for the typical fragmentmass and migration time along with published models of protostellar disksaround both UMP and primordial composition stars to explore the formation oflow-mass Pop III stars via disk fragmentation. We find evidence that thesurvival of low-mass secondaries around solar-mass UMP primaries implies thesurvival of solar-mass secondaries around Pop III primaries with masses 10M_Sun < M_Star < 100 M_Sun. If true, this inference suggests that solar-massPop III stars formed via disk fragmentation could survive to the present day.

An Ultra Metal-poor Star Near the Hydrogen-burning Limit