NUCLEOSYNTHESIS IN HIGH-ENTROPY HOT BUBBLES OF SUPERNOVAE AND ABUNDANCE PATTERNS OF EXTREMELY METAL-POOR STARS

Journal Article · Wed Sep 01 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/720/1/L1· OSTI ID:21452853

Izutani, Natsuko; Umeda, Hideyuki ^[1]

---

1. Department of Astronomy, School of Science, University of Tokyo, Hongo, Tokyo 113-0033 (Japan)

There have been suggestions that the abundance of extremely metal-poor (EMP) stars can be reproduced by hypernovae (HNe), not by normal supernovae (SNe). However, recently it was also suggested that if the innermost neutron-rich or proton-rich matter is ejected, the abundance patterns of ejected matter are changed, and normal SNe may also reproduce the observations of EMP stars. In this Letter, we calculate explosive nucleosynthesis with various Y {sub e} and entropy, and investigate whether normal SNe with this innermost matter, which we call the 'hot-bubble' component, can reproduce the abundance of EMP stars. We find that neutron-rich (Y {sub e} = 0.45-0.49) and proton-rich (Y {sub e} = 0.51-0.55) matter can increase Zn/Fe and Co/Fe ratios as observed, but tend to overproduce other Fe-peak elements. In addition, we find that if slightly proton-rich matter with 0.50 {<=} Y {sub e} < 0.501 with s/k {sub b} {approx} 15-40 is ejected as much as {approx}0.06 M {sub sun}, even normal SNe can reproduce the abundance of EMP stars, though it requires fine-tuning of Y {sub e}. On the other hand, HNe can more easily reproduce the observations of EMP stars without fine-tuning. Our results imply that HNe are the most likely origin of the abundance pattern of EMP stars.

• OSTI ID: 21452853
• Journal Information: Astrophysical Journal Letters, Vol. 720, Issue 1; Other Information: DOI: 10.1088/2041-8205/720/1/L1; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
ASTROPHYSICS
ENTROPY
NEUTRONS
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
PROTONS
SUPERNOVAE
BARYONS
BINARY STARS
ELEMENTARY PARTICLES
ERUPTIVE VARIABLE STARS
FERMIONS
HADRONS
NUCLEONS
PHYSICAL PROPERTIES
PHYSICS
STARS
SYNTHESIS
THERMODYNAMIC PROPERTIES
VARIABLE STARS