08-5-29(四)下午北大天文系会议室 刘浩斌博士学术报告

发信人: bora (亚得里亚海边的岁月), 信区: Astronomy
标  题: PKU-KIAA刘浩斌博士学术报告
发信站: 北大未名站 (2008年05月27日21:38:07 星期 二) , 站内信件

北京大学KIAA-PKU 刘浩斌博士将在北京大学科维理天文与天体物理研究所 & 天文系作学术报告：

题目：Evolution and Fate of Extremely-Metal Poor Stars

时间:  2008年5月29日(星期四),下午3:30
地点:  北京大学理科二号楼2907(天文系会议室)

欢迎参加！
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Abstract

Most carbon-enhanced metal-poor(CEMP) stars observed are probably formed
by binary mass transfer from a low-metallicity AGB companion. Thus it is
important to understand the evolution of extremely low AGB stars.

I will show that HE 0107-5240, the second most metal-poor star observed so
far, can be formed by mass transfer from a six to seven solar mass
companion (Lau et al 2007) after second dredge up.  However, this
mechanism only works for extremely metal-poor stars. In order to fit the
observation of other observed CEMP stars, some form of flash-driven mixing
mechanism may still be needed.

How different mixing schemes affect the critical mass and metallicity of
helium-flash deep driven mixing is currently investigated. Moreover, a few
models evolving through the mixing episode will be discussed to illustrate
the effect of the helium flash driven mixing quantitatively.

On the other hand, models by several authors such as Gil-Pons et al (2007)
and Lau et al (2008) shows that zero-metallicity AGB stars could end their
lives as type 1.5 supernovae. Lau et al (2008) shows that these stars show
no third dredge up and the core grows much faster after thermal pulses
cease.  Thus the probability of supernova type 1.5 is higher than
previously estimated.

The possibility of type 1.5 supernovae occurring in extremely metal-poor
stars is currently investigated by a grid of AGB stars with different mass
and metallicity. The possibility of supernovae type 1.5 and the
explanation for the absence of third dredge-up for extremely metal-poor
AGB stars will be discussed.
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