Understanding subdwarf B stars through asteroseismology

AST 0307480 PI Reed经过几十年的恒星演化理论和观测恒星天文学的进步，我们银河系中大多数恒星演化的后期阶段--它们脱落外层并暴露出致密核心的阶段--隐藏着许多尚未解答的问题。最近，我们已经开始利用一个强大的工具，天体地震学，探测恒星的内部和模拟其结构的振荡和脉动的恒星。亚矮星B（sdB）是位于Hertzsrung-Russell图水平分支的演化恒星，被认为是低质量白色矮星的前身。它们的祖先是像我们的太阳一样的恒星。到目前为止，观测的重点一直是发现新的脉动sdB星。随着30多个成员的发现，这个领域现在已经足够成熟，可以把我们享受的成功应用于白色矮星的sdB恒星。要做到这一点，需要获得足够的光度数据，以解决往往复杂的脉动结构的个别对象。作为水平分支星，sdB星在其核心燃烧氦，由于它们有限的氢包层，这些星没有壳层氢燃烧，简化了它们的结构，使它们更容易建模。 到目前为止，只有少数脉动sdB星解决脉动光谱，其中一些揭示了非常有趣的结果。这项研究的目标是充分应用天体地震学的工具，sdB星通过解决几个额外的成员的脉动谱。这需要大量的望远镜时间在国家设施，贝克天文台（由我们的家庭机构运营）和与国际合作者的多站点观测活动之间分配。脉动恒星也可以用来寻找行星。sdB星的伴星可以通过脉动相位的周期性变化被探测到。这样的测量很容易对长周期的亚木星质量行星敏感。更广泛的影响。 本科生将协助获得和减少本研究项目中的数据。通过让本科生接触研究，他们能够更好地决定天文学是否是他们正确的职业道路。此外，它允许西南密苏里州的学生竞争力申请研究生课程的基础上强大的本科研究经验。

AST 0307480PI ReedAfter decades of progress in both stellar evolution theory and observational stellar astronomy, the late stages of evolution of most of the stars in our Galaxy - stages in which they shed their outer envelopes and expose their compact cores - conceal many still-unanswered questions. Recently, we have begun to exploit a powerful tool, astroseismology, for probing the interiors of stars and modeling their structure from oscillations and pulsations of the stars. Subdwarf B (sdB) stars are evolved stars located on the so-called horizontal branch of the Hertzsrung-Russell diagram, and they are thought to be the precursors of low mass white dwarf stars. Their progenitors are stars like our Sun. To date, the observational emphasis has been on discovering new pulsating sdB stars. With over 30 members discovered, the field is now mature enough to turn the success we have enjoyed applying astroseismology of white dwarfs to sdB stars. To do so requires that sufficient photometric data be obtained to resolve the often complex pulsation structure of individual objects. As horizontal branch stars, sdB stars are burning helium in their cores, With their limited hydrogen envelopes, these stars have no shell hydrogen burning simplifying their structure, and making them easier to model. Thus far only a few pulsating sdB stars have resolved pulsation spectra, some of which have revealed very interesting results. The goal of this research is to fully apply the tools of astroseismology to sdB stars by resolving the pulsation spectra of several additional members. This requires substantial telescope time to be split between national facilities, Baker Observatory (operated by our home institution), and multi-site observational campaigns with international collaborators. Pulsating stars may also be used to look for planets. Companions to sdB stars can be detected as periodic variations in the pulsation phases. Such measurements are readily sensitive to sub-Jupiter mass planets with long periods. Broader impacts. Undergraduate students will assist in obtaining and reducing the data in this research project. By exposing undergraduate students to research, they are better able to decide if astronomy is the correct career path for them. Additionally, it allows Southwest Missouri State's students to competitively apply for graduate programs based on a strong undergraduate research experience.