Studies on Blue Straggler Stars in different stellar environments

【日時】2月10日(水) 10:30~12:00
【場所】国立天文台・三鷹 北研1階講義室
【タイトル】Studies on Blue Straggler Stars in different stellar environments
【発表者(敬称略)】趙正実 (総研大 D1・三鷹、指導教員 有本信雄)
Blue straggler stars (BSS) are located above and blue-ward of MS turn-off in a CMD of stellar clusters. They have been found in many stellar environments in observational studies during past 50 years.
Two different mechanisms of them are commonly believed nowadays: mass transfer in binary systems and stellar merger occurred through a direct stellar collision. The former might be dominant in lower density environments, whereas the later might be considered to mainly occur in high-density environments.
The most studies on these objects are focus on the globular clusters because the dynamical environment of them could produce both of BSS formed by different mechanisms. In recent years researches for BSS in dwarf spheroidal galaxies (dSphs) are also increased.
Interestingly there is found a statistically significant anti correlation between the relative BSS frequency respect to HB stars and absolute magnitude in dwarf galaxies, it is similar to that observed in globular clusters.
In this presentation, the previous studies on BSS, involving with observational properties- binarity, rotation velocity, abundance, radial distribution in different environments etc., will be introduced.
However, these properties were not enough to distinguish different formation mechanisms.
It is clear that a great deal of work remains to be done both observationally and theoretically on characteristics and physical mechanisms of BS.