Orbital solutions study of Subdwarf B wide binary systems

亚矮星B宽双星系统轨道解研究

• 批准号: 2108975
• 负责人: Tomomi Otani
• 金额: $ 23.24万
• 依托单位: Embry-Riddle Aeronautical University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2108975&HistoricalAwards=false
• 关键词: Orbital; solutions; study; Subdwarf; wide

Subdwarf B (sdB) stars are post main-sequence stars that paradoxically are small (0.10-0.25 solar radii), low mass (~0.5 solar masses), very hot (20,000 - 40,000 K), and extremely hydrogen deficient, being composed almost entirely of helium. These exotic objects are the dominant hot stellar population in globular clusters, spiral bulges, and elliptical galaxies, and are thought to form in binary systems through common envelope ejection (CEE), Roche-lobe overflow (RLOF), or white-dwarf mergers (WD2). Of the three formation "channels" only the CEE is easily observed using radial velocity measurements due to their short (hours to few-day) orbital periods. A research team at Embry-Riddle Aeronautical University will use small (1-m) telescopes to measure periodic arrival time variations in the pulsations of sdB stars, the same approach used by Ole Romer in 1676 to determine the speed of light, to increase the number of confirmed long period sdB systems and solitary sdB stars to gauge the formation channels. This technique is also capable of detecting Jupiter-like planets should they exist in these systems. This research will support two undergraduate researchers and one graduate student.To improve theoretical models of sdB star formation and evolution many more long-period sdB binary systems with a variety of orbital parameters will be needed. However, this would require many nights on large telescopes for an accurate radial velocity analysis. The pulsation timing method is much more efficient approach as 30% of sdB stars exhibit stable pulsations, with periods (p-mode) ranging from 1.5 - 5 minutes. Pulse arrival times change periodically as the sdB star’s reflex motion is manifested by the changing distance along the line of sight. This method is particularly effective for finding orbital solutions for long period binary (or planetary) systems, so this can be efficiently used for observational studies for RLOF and white-dwarf merger (WD2) channels. Frequent observations with 1-m class telescope are required, but the research team has access to the three 1-m telescopes of the Southeastern Association for Research in Astronomy (SARA) Observatory as well as a 1-m telescope on the ERAU campus. They will also search for pulsation period changes resulting due to binary evolution to estimate the current stage of each sdB star. The results will lead to a better understanding of sdB star formation and so a more complete understanding of the stellar populations in our own and other galaxies.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.

次矮星B（sdB）是后主序星，矛盾的是它们很小（0.10-0.25太阳半径），质量很低（~0.5太阳质量），温度很高（20，000 - 40，000 K），而且极度缺乏氢，几乎完全由氦组成。这些奇异的天体是球状星团、螺旋星系和椭圆星系中占主导地位的热恒星群，并被认为是通过共同包层抛射（CEE）、罗氏瓣溢出（RLOF）或白矮星合并（WD 2）形成的双星系统。在这三个编队“通道”中，只有CEE由于其轨道周期短（数小时至数天），使用径向速度测量很容易观测到。安布里-里德尔航空大学的一个研究小组将使用小型（1米）望远镜来测量sdB恒星脉动的周期性到达时间变化，与Ole Romer在1676年使用的确定光速的方法相同，以增加已确认的长周期sdB系统和孤立sdB恒星的数量来测量形成通道。这种技术也能够探测到类似彗星的行星，如果它们存在于这些系统中。为了改进sdB星星形成和演化的理论模型，需要更多具有不同轨道参数的长周期sdB双星系统。然而，这将需要在大型望远镜上进行许多夜晚的精确径向速度分析。脉动计时方法是更有效的方法，因为30%的sdB星表现出稳定的脉动，周期（p模式）范围为1.5 - 5分钟。由于sdB星星的反射运动表现为沿视线沿着变化的距离，因此脉冲到达时间周期性地变化。 这种方法对于寻找长周期双星（或行星）系统的轨道解特别有效，因此可以有效地用于RLOF和白矮星合并（WD 2）通道的观测研究。需要经常使用1米级望远镜进行观测，但研究小组可以使用东南天文学研究协会（SARA）天文台的三台1米望远镜以及ERAU校园内的一台1米望远镜。他们还将寻找由于双星演化而导致的脉动周期变化，以估计每个sdB星星的当前阶段。研究结果将有助于更好地理解sdB星星的形成，从而更全面地了解我们自己和其他星系中的恒星群。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。

项目成果

A Monte Carlo Method for Evaluating Empirical Gyrochronology Models and Its Application to Wide Binary Benchmarks

• DOI: 10.3847/1538-4357/ac6035
• 发表时间: 2021-05
• 期刊: The Astrophysical Journal
• 作者: T. Otani;T. Hippel;D. Buzasi;T. Oswalt;Alexander Stone-Martinez;Patrice Majewski Embry-Riddle Aeronautical University-Patrice-Majewski-Embry-Riddl

Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

• DOI: 10.3847/1538-4357/ac3a72
• 发表时间: 2021-09
• 期刊: The Astrophysical Journal
• 作者: T. Otani;A. Lynas-Gray;D. Kilkenny;C. Koen;T. von Hippel;M. Uzundag;M. Vučković;C. Pennock;R. Silvotti