Collaborative Research: Searching for the Expelled Envelope of Stripped-Envelope Supernovae

天文学家研究超新星是因为恒星灾难的最大亮度可以相当于10亿个太阳，这是一个令人敬畏的奇观。通过研究哪些恒星成为超新星，我们对恒星生命周期的过程有了新的认识。爆炸使星星膨胀变薄，这使我们能够更深入地观察爆炸物质。物质以光速的百分之几的速度被抛入太空。当这种情况发生时，天文学家可以读取来自恒星外层的信号 探测这颗星星爆炸前后的性质。通过这些观测，我们对致密天体的形成有了新的认识，比如中子星和黑洞。喷出的物质富含新元素，因此超新星是宇宙核演化的主要驱动力。超新星也是星系物理结构和组成的重要因素。超新星释放的能量可能会刺激或抑制恒星的形成。超新星也可能在超新星加热的星系风中从星系中喷出物质。此外，超新星是银河系外距离的精确指示器。通过对超新星的研究，我们可以确定宇宙膨胀的历史。超新星研究的一个主要问题是确定恒星在爆炸前如何脱落质量。调查人员将研究爆炸星星的相互作用，当爆炸与爆炸前被驱逐的物质相撞时。对这些问题的深入理解将扩大我们对恒星如何以及何时喷射物质的了解。研究人员试图确定恒星是否有多次质量损失。他们还想知道质量的损失如何改变星星周围物质的分布。 为了更好地理解这些问题，研究人员将选择不含氢的恒星作为超新星爆炸时的研究对象，因为这意味着恒星要么已经排出了所有的氢，由于碰撞的性质与超新星的性质有关，研究人员还将确定碰撞的强度如何随时间变化。这项研究项目将有助于我们进一步了解我们在宇宙中的位置。它将有助于培养STEM领域的年轻科学家。它将促进公众对科学的更深入理解。研究人员使用德克萨斯州麦克唐纳天文台的2.7米哈兰J.史密斯望远镜来寻找超新星的碰撞。窄带滤波器允许快速搜索氢特征的发射，这些特征表明超新星与先前排出的富氢物质碰撞的存在。窄带滤波器的观测结果也表明了氢发射强度的变化，这是相互作用性质的进一步线索。研究人员将继续研究与Hobby-Eberly望远镜的碰撞，以确认氢发射来自冲击物质，而不是来自星际介质中的氢浓度。他们在其他波长进行观测，包括使用NSF的超大阵列射电天文台，以进一步限制冲击材料的性质-温度和密度。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。

Astronomers study supernovae because the maximum luminosity of a stellar catastrophe can equal that of a billion suns, which is an awesome spectacle to see. By studying which stars become supernovae, we gain new insights into the course of the stellar life cycle. The explosion causes the star to expand and thin out, and this allows us to see ever deeper into the exploding matter. Matter is thrown into space at a few percent of the speed of light. When this happens, astronomers can read the signals from the outer layers of the stars and probe the nature of the star both before and after it exploded. Through these observations, we gain new insight into the formation of compact objects, such as neutron stars and black holes. The ejected matter is enriched in new elements, and thus, Supernovae are principal drivers of the nuclear evolution of the Universe. Supernovae are also an important factor in the physical structure and composition of galaxies. The energy released by supernovae may stimulate or inhibit the formation of stars. Supernovae may also eject matter from galaxies in supernova-heated galactic winds. Additionally, Supernovae serve as exquisite indicators of extragalactic distances. Through the study of Supernovae, we can determine the history of the cosmic expansion.A major issue in supernova research is determining how stars shed mass prior to explosion. The investigators will study the interaction of the exploding star, when the explosion collides with matter that was expelled before the explosion. Deeper understanding of these issues will expand our knowledge of how and when stars eject matter. The investigators seek to determine whether stars have multiple episodes of mass loss. They also want to know how the loss of mass alters the distribution of matter around the star. To better understand these questions, the investigators will study select stars that contain no hydrogen by the time they explode as supernovae because this means either the stars have expelled all their hydrogen-rich material into space or a companion star has accreted it. The investigators will also determine how the strength of the collision varies in time because the collision properties are related to the nature of the underlying supernova.This research project will help further our understanding of our place in the Universe. It will serve to train young scientists in the STEM fields. It will promote deeper understanding of science in the public. It will be accompanied by broad outreach in appropriate venues for writing and speaking.The investigators use the 2.7m Harlan J. Smith telescope at McDonald Observatory, in Texas, to search for the collision of supernovae. Narrow-band filters permit a rapid search for emission of hydrogen features that signify the presence of the collision of the supernova with previously-expelled hydrogen-rich material. The narrow-band filter observations also indicate variations in the strength of the hydrogen emission, which is a further clue to the nature of the interaction. The investigators will continue studies of collisions with the Hobby-Eberly Telescope to confirm that the hydrogen emission is from shocked material and not from ambient concentrations of hydrogen in the interstellar medium. They perform observations at other wavelengths, including the use of the NSF's Very Large Array radio observatory, to further constrain the properties - temperature and density - of the shocked material.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.