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Observational study on the evolution of AGB stars and their mass-loss

AGB恒星演化及其质量损失的观测研究

基本信息

批准号：
12640234
负责人：
TANABE Toshihiko
金额：
$ 2.05万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640234/
关键词：
stellar evolution stars - late stages stars - AGB mass-loss cool stars long period variables circumstcllar dust Magellanic Clouds 質量放出現象

项目摘要

It is well known that globular clusters (GCs) associated with the Magellanic Clouds (MCs) are an ideal test field for the theory of stellar evolution because fundamental parameters of a star such as the mass, luminosity, metallicity, etc. can be estimated. We performed repeated observations of GCs in the MCs at South African Astronomical Observatory (SAAO) with a newly built 1.4 m telescope, IRSF and a near-infrared camera, SIRIUS and obtained the following results.1. We found that stars in the upper AGB all show variabilities and their periods and ampitudes tend to increase along AGB. At the tip of the AGB, stars turn to be Ions period variables, possibly Mira types.2. The mass-loss does not seem to occur along AGB but occur in a some special phase, probably in a very late phase.Although we found many variable stars, we could not detect short-period and possibly low amplitude variables because our observational chances were not dense. When the variability appears and how it evolves along AGB and the relationship between the luminosity and period along AGB still remains a future work.

与麦哲伦云（Magellanic Cloud，MC）相伴的球状星团（globular clusters，GC）是恒星演化理论的理想实验场，因为它可以估算出星星的质量、光度、金属丰度等基本参数。我们在南非天文台（SAAO）用一台新建成的1.4米望远镜IRSF和一台近红外相机SIRIUS对MCs中的GC进行了重复观测，获得了以下结果.我们发现，在AGB上部的恒星都表现出变化，它们的周期和振幅都有沿AGB沿着增大的趋势。在AGB的尖端，恒星变成离子周期变量，可能是Mira类型。虽然我们发现了许多变星，但由于观测机会不多，未能探测到短周期和低振幅变星。光变何时出现、如何沿AGB沿着演化以及光度与周期沿着的关系有待进一步研究。