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

天文学家研究超新星是因为恒星灾难的最大光度可以相当于10亿个太阳的亮度，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见解。爆炸导致恒星膨胀和变薄，这使我们能够看到爆炸物质的更深层次。物质以光速的几分之一的速度被抛入太空。当这种情况发生时，天文学家可以读取恒星外层的信号，并探测恒星爆炸前后的性质。通过这些观测，我们对中子星和黑洞等致密天体的形成有了新的认识。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。超新星也是影响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银河系风中从星系中喷出物质。此外，超新星也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。超新星研究中的一个主要问题是确定恒星在爆炸前如何脱离质量。当爆炸与爆炸前排出的物质相撞时，研究人员将研究爆炸恒星的相互作用。对这些问题的深入理解将扩大我们对恒星如何以及何时弹出物质的了解。研究人员试图确定恒星是否有多次质量损失。他们还想知道质量损失如何改变恒星周围物质的分布。为了更好地理解这些问题，研究人员将研究一些在超新星爆炸时不含氢的恒星，因为这意味着要么恒星已经将所有富氢物质释放到太空中，要么伴星已经将其吸积。研究人员还将确定碰撞的强度如何随时间变化，因为碰撞的性质与底层超新星的性质有关。这项研究项目将有助于进一步了解我们在宇宙中的位置。它将用于培训STEM领域的年轻科学家。它将促进公众对科学的更深入了解。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·史密斯望远镜来搜索超新星的碰撞。窄带滤光片允许快速搜索氢特征的发射，这些特征表明超新星与先前喷出的富氢物质发生了碰撞。窄带滤光片观测还表明氢发射强度的变化，这是进一步了解相互作用性质的线索。研究人员将继续对与霍比-埃伯利望远镜的碰撞进行研究，以确认氢来自受冲击的物质，而不是来自星际介质中周围浓度的氢。他们在其他波长进行观测，包括使用NSF的甚大阵列射电天文台，以进一步限制受冲击材料的性质-温度和密度。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.