Collaborative Research: The Importance of Binarity on the Origin of Wolf-Rayet Stars

该项目旨在展示高质量恒星如何失去最外层，暴露出它们的核心。这些天体被称为沃尔夫-拉叶星（WR）。它们的大部分氢都消失了，它们由核燃烧的产物组成，如氦，碳和氧。WR型恒星已接近生命的尽头，注定会爆发成壮观的超新星。有两种方法可以形成这些WR。在第一种情况下，外层被“恒星风”吹走，在这种情况下，物质被强光的压力从星星上吹走。在第二种方法中，物质被轨道运行的伴星星星的引力从星星上拉下来。很可能一些WR星以一种方式形成，而另一些则形成另一种。该项目的目标是找出每种方法形成的WR星的比例。这一结果在科学上非常重要，因为这些大质量恒星在宇宙生态中起着至关重要的作用，它们制造了构成我们星球和地球上生命的元素。它们在生命结束时的强烈爆炸将这些元素释放到太空中，引发了下一代恒星和行星的形成。这些观察也将为本科生提供暑期实习项目。该项目包括编制和免费分发大学天文学练习。调查员小组将采用三种相辅相成的办法。首先，他们将测量富氮沃尔夫-拉叶星（WN）代表性样本的光度和化学成分，并将其与进化模型预测的结果进行比较。第二，研究神秘的“WN 3/O3”星的性质。它们要么是剥离双星的原型，要么是O型星和WR之间缺失的一环。第三，他们将对大麦哲伦星云和小麦哲伦星云中的O型恒星进行系统的调查。O星和WR星的相对数量作为质量（光度）的函数是WR起源的最基本诊断之一。这三个程序一起将把数字和不确定性的二进制文件的比例形成的每一个机制。作者还将构建一个包含1000颗明亮恒星的高分辨率光谱图集，涵盖广泛的光谱类型和光度类别。这本地图集的目的是作为一个启发性的资源，不仅为天文学家，而且为天文学学生。它将用于北方亚利桑那大学的本科生实验室练习。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is designed to demonstrate how high-mass stars lose their outermost layers, exposing their cores. Such objects are known as Wolf-Rayet (WR) stars. Most of their hydrogen is gone, and they are made up of the products of nuclear burning such as helium, carbon, and oxygen. WR stars are near the ends of their lives and are destined to explode as spectacular supernovae. There are two methods by which these WRs might form. In the first of these, the outer layers are removed by "stellar winds," in which matter is pushed off the star by the pressure of their intense light. In the second method, material is pulled off the star by the gravity of an orbiting companion star. It is likely that some WR stars form one way, while others form the other. The goal of this project is to find what fraction of WR stars is formed by each method. This result will be important scientifically, because these high-mass stars play a vital role in the ecology of the Universe, manufacturing the elements that make up our planet and the life on it. Their intense explosions at the ends of their lives release these elements into space, triggering the formation of the next generation of stars and planets. These observations will also provide summer internship projects for undergraduates. The project includes the construction and free distribution of college-level exercises in astronomy. The investigator team will use three complementary approaches. First, they will measure the luminosities and chemical composition of representative samples of nitrogen-rich Wolf-Rayet stars (WN) and compare these to those predicted by the evolutionary models. Second, the nature of the enigmatic "WN3/O3" stars will be investigated. These are either archetypes of stripped binaries or a missing link between O stars and WRs. Third, they will conduct a systematic survey for O-type stars in the Large and Small Magellanic Clouds. The relative number of O and WR stars as a function of mass (luminosity) is one of the most fundamental diagnostics of the origins of WRs. Together these three programs will put numbers and uncertainties on the fraction of binaries formed by each mechanism. The authors will also construct a high-resolution spectral atlas of 1000 bright stars covering a wide range of spectral types and luminosity classes. This atlas is intended as a heuristic resource available not only for astronomers but also for astronomy students. It will be used in undergraduate lab exercises at Northern Arizona University. These spectra and teaching units will then be made freely available to everyone through a website.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.