Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars

Details Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars

2010-05-14

arxiv.org/abs/1005.2475v1

Astronomy and Astrophysics

Astrophysics

Galaxy Astrophysics

20 pages, 14 figures. ApJ accepted

Scientific paper

We investigate the star formation and chemical evolution in the early universe by considering the merging history of the Galaxy in the {\Lambda}CDM scenario according to the extended Press-Schechter theory. We give some possible constraints from comparisons with observation of extremely metal-poor (EMP) stars. We demonstrate that (1) The hierarchical structure formation can explain the characteristics of the observed metallicity distribution function (MDF) including a break around [Fe/H]~-4. (2) A high mass IMF of peak mass ~10Msun with the contribution of binaries, derived from the statistics of carbon enhanced EMP stars (Komiya et al. 2007), predicts the frequency of low-mass survivors consistent with the number of EMP stars observed for -4~<[Fe/H]~<-2.5. (3) The stars formed from primordial gas before the first supernova explosions in their host mini-halos are assigned to the HMP stars with [Fe/H]~-5. (4) There is no indication of significant changes in the IMF and the binary contribution at metallicity -4~<[Fe/H]~<-2.5, or even larger as long as the field stars of Galactic halo are concerned. We further study the effects of the surface pollution through the accretion of ISM along the chemical and dynamical evolution of the Galaxy for low-mass Pop.III and EMP survivors. Because of shallower potential of smaller halos, the accretion of ISM in the mini-halos in which these stars were born dominates the surface metal pollution. This can account for the surface iron abundances as observed for the HMP stars if the cooling and concentration of gas in their birth mini-halos is taken into account. We also study the feedback effect from the very massive Pop. III stars. The metal pre-pollution by PISNe is shown to be compatible with the observed lack of their nucleosynthetic signatures when some positive feedback on gas cooling works and changes IMF from being very massive to being high mass.

Affiliated with

Also associated with

No associations

Rating

Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-519057