Origin of the CEMP-no Group Morphology in the Milky Way
| Autor: | Di Tian, Jinmi Yoon, Devin D. Whitten, Timothy C. Beers |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
Milky Way FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Galactic halo Group (periodic table) 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences Dwarf galaxy Physics Star formation Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Galaxy Stars Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Halo Astrophysics::Earth and Planetary Astrophysics |
| Popis: | The elemental-abundance signatures of the very first stars are imprinted on the atmospheres of CEMP-no stars, as various evidence suggests they are bona-fide second-generation stars. It has recently been recognized that the CEMP-no stars can be sub-divided into at least two groups, based on their distinct morphology in the $A$(C)-[Fe/H] space, indicating the likely existence of multiple pathways for their formation. In this work, we compare the halo CEMP-no group morphology with that of stars found in satellite dwarf galaxies of the Milky Way -- a very similar $A$(C)-[Fe/H] pattern is found, providing clear evidence that halo CEMP-no stars were indeed accreted from their host mini-halos, similar in nature to those that formed in presently observed ultra-faint dwarfs (UFDs) and dwarf spheroidal (dSph) galaxies. We also infer that the previously noted "anomalous" CEMP-no halo stars (with high $A$(C) and low [Ba/Fe] ratios) that otherwise would be associated with Group I may have the same origin as the Group III CEMP-no halo stars, by analogy with the location of several Group III CEMP-no stars in the UFDs and dSphs and their distinct separation from that of the CEMP-$s$ stars in the $A$(Ba)-$A$(C) space. Interestingly, CEMP-no stars associated with UFDs include both Group II and Group III stars, while the more massive dSphs appear to have only Group II stars. We conclude that understanding the origin of the CEMP-no halo stars requires knowledge of the masses of their parent mini-halos, which is related to the amount of carbon dilution prior to star formation, in addition to the nature of their nucleosynthetic origin. 13 pages, 3 figures, and 1 table, accepted for publication in the Astrophysical Journal with minor changes |
| Databáze: | OpenAIRE |
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