LEAPS-MPS: A Systematic Investigation of Transient Behavior in RR Lyrae Variable Stars

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。天琴座RR恒星是一类变星，其脉动与其固有光度有相对直接的关系。因此，这些恒星提供了一个“标准蜡烛”，用来测量整个银河系(甚至到其他星系)的距离。由于天琴座RR恒星在整个宇宙中设定距离尺度的作用，在其机制的大致轮廓首次被描述几十年后，人们仍在继续研究它们的脉动。这种理解的任何改变都可能对天文学的其他部分产生重大影响。该团队将研究脉动的基本模式的幅度变化，以及它的第一个泛音，以及这些原本是径向脉动的恒星上的非径向脉动。他们将进行地面光谱观测，而TESS航天器则对同一颗恒星进行光度观测，以便进行实时比较。本科生来自西班牙裔服务机构中代表性不足的群体，他们将参与研究的各个方面。该团队最近发现了双模天琴座RR恒星V338 Boo的基本脉动模式的幅度发生了变化。基本脉动的幅度在几十天的尺度上变化，而第一泛音的幅度保持不变。此外，其他研究小组最近发现了非径向脉动，其幅度也在数十天的范围内变化。该团队将观测一组RR-Lyrae恒星，以寻找类似的脉动变化，并将进一步与TESS卫星进行共入射观测，以比较实时光谱变化与光度变化。该团队将观测已知的天琴座RR恒星；对这些模式和变化的研究将为恒星内部的天体物理模型提供信息。这一奖项反映了NSF的法定任务，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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). RR Lyrae stars are a class of variable star whose pulsations have a relatively straightforward relationship to their intrinsic luminosities. As such, these stars provide a ‘standard candle’ against which to measure distance throughout the galaxy (and even to other galaxies). Because of their role in setting distance scales throughout the universe, pulsations of RR Lyrae stars continue to be studied decades after the broad outline of the mechanism was first described. Any change in that understanding could have significant implications on other parts of astronomy. The team will study changes in the amplitude of the fundamental mode of pulsation, along with its first overtone, as well as non-radial pulsations on these otherwise radially pulsing stars. They will make ground-based spectroscopic observations while the TESS spacecraft conducts photometric observations of the same star, allowing real-time comparison. Undergraduate students, drawn from under-represented groups at a Hispanic Serving Institution, will be involved in all aspects of the research. The team recently discovered changes in the amplitude of the fundamental pulsation mode of the double-mode RR Lyrae star V338 Boo. The fundamental pulsation’s amplitude is found to change on the scale of many tens of days, while the first overtone’s amplitude remains constant. Further, other teams have recently discovered non-radial pulsations whose amplitudes also change on the scale of tens of days. The team will observe a set of RR-Lyrae stars to look for similar changes in pulsations, and will furthermore conduct co-incident observsations with the TESS satellite to compare real-time spectroscopic variations with photometric variations. The team will observe known RR Lyrae stars; the study of these modes and variations will inform astrophysical models of stellar interiors.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.