它已经变成了天文学家所谓的‘亚巨星’，也就是说成为已经耗尽了核心中氢燃料的恒星，并且正在变成红巨星。
It has become what astronomers call a subgiant , or a star that has exhausted all of its hydrogen fuel in the core and is on its way to becoming a red giant .
亚巨星