The Life Cycles of Massive Stars: A New Approach to Measure Mass Loss

白色矮星是一颗低质量星星生命末期产生的恒星残骸，密度非常大，有行星大小。大约98%的恒星--包括我们的太阳--将以白色矮星的形式结束它们的生命。这个研究小组将发现并分析数十颗位于银河系非常年轻的星星团中的白色矮星。他们的研究将为恒星天体物理学提供重要的见解。他们将测量并比较白色矮星的质量与其他仍在进行聚变的恒星的质量，以确定它们在一生中损失了多少质量。这将被用来定义区分白色矮星形成和核心坍缩超新星的临界质量。他们将使用现有调查的数据，并使用光学望远镜获得新的数据。第二个目标是确定研究中年轻星星团的精确年龄。更广泛的影响包括进一步培训一名博士后科学研究人员和公共宣传。PI将继续他关于恒星和恒星死亡的公开讲座系列。他还将与附近学校的非洲裔美国人和印度学生合作，并帮助马里兰州的全国有色人种协进会科学奥林匹克运动会。一旦在星星集群中确定了白色矮星候选者，研究人员将对每个集群的颜色-星等图进行详细分析，以得出母系统的属性。接下来，他们将在4至10米望远镜上使用多目标光谱仪获得新发现的白色矮星的数据，并通过将巴尔末线光谱与团队的白色矮星大气和冷却模型拟合来确定基本的恒星属性（如有效温度，log g，质量，光度和冷却年龄）。 他们将通过在白色矮星质量分布中建立截断来测量分离白色矮星和超新星形成的临界质量。

White dwarfs are very dense, planet-sized, stellar remnants produced at the end of a low-mass star's life. About 98% of all stars - including our Sun - will end their lives as white dwarfs. This research team will find and analyze dozens of white dwarfs that are located in very young star clusters in the Milky Way galaxy. Their study will provide critical insights about stellar astrophysics. They will measure and compare the masses of white dwarfs with those of other stars still undergoing fusion, in order to determine how much mass is lost over their lifetimes. This will be used to define the critical mass that separates white dwarf formation from core collapse supernova. They will use data from existing surveys and obtain new data using optical telescopes. A secondary goal is to determine the precise ages of the young star clusters in the study. Broader impacts include further training of a postdoctoral researcher in science and public outreach. The PI will continue his public lecture series on stars and stellar death. He will also collaborate with African American and Indian students at nearby schools and help with the NAACP Scientific Olympics in Maryland.Once white dwarf candidates are identified in a star cluster, the researchers will perform a detailed analysis of each cluster's color-magnitude diagram to derive the properties of the parent system. Next, they will obtain data of the newly discovered white dwarfs with multi-object spectrographs on 4 to 10-m telescopes and determine fundamental stellar properties (such as effective temperature, log g, mass, luminosity and cooling age) by fitting the Balmer line spectra to the team's white dwarf atmosphere and cooling models. They will measure the critical mass separating white dwarf from supernova formation by establishing a truncation in the white dwarf mass distribution.