Precision RR Lyrae Distances for a Population II Route to the Distance Scale

人口 II 路线的精确 RR Lyrae 距离到距离标度

• 批准号: 1714534
• 负责人: Massimo Marengo
• 金额: $ 27.93万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1714534&HistoricalAwards=false
• 关键词: Precision; RR; Lyrae; Distances; Population

The investigator will analyze the change in brightness of a special class of variable stars, called RR Lyrae stars. These pulsating stars are very common in the old stellar clusters found in the Milky Way and other galaxies. These stars are important because they can be used as yardsticks to measure distances on scales of thousands to millions of light years. Distances are measured using a relation between their variability period (the time it takes these stars to cycle through their brightness variations), and their intrinsic luminosity. This "period-luminosity" relation makes them ideal "standard candles." The investigator will better calibrate measurements of distances across the universe, using RR Lyrae stars. Accurate distances are needed to better understand the expansion rate and the age of the cosmos. They also hope to achieve a better understanding of the physics of stars and of the stellar clusters where RR Lyrae stars are found.The Iowa State University Physics & Astronomy department engages the local community with numerous outreach activities. The student-run Planetarium shows, in particular, draw large crowds of all ages, and are offered monthly to the public, as well as to the local K-12 schools (over 40,000 students in Ames and nearby school districts). This project will refurbish telescope equipment previously located off-campus at the Fick observatory facility (now discontinued) making it available to the public as part of a new in-campus, wheelchair-accessible, observation site for outreach activity (e.g., star and Sun parties following planetarium shows for the general public and K-12 students). They will also prepare two new modules for planetarium shows based on the science of variable stars and the cosmological distance scale as a way to communicate to the local community an example of federally-funded research that is done at Iowa State University.Since Henrietta Leavitt discovered the Cepheid Period-Luminosity relation in 1908, pulsating stars have been an invaluable distance estimator. More than a century after this groundbreaking result, Cepheids are still the cornerstone of an ever more intricate cosmological distance ladder. Recent results from the Planck mission, however, reveal some tension between the value of cosmological parameters derived from the study of the cosmic background radiation with respect to "direct" measurements still crucially relying on Cepheids. With this project, the investigators aim to provide an alternative Population II stellar distance estimator based on the newly re-discovered period-luminosity relation of RR Lyrae variables and the availability of high precision parallaxes from the Gaia spacecraft. The investigators will (1) calibrate the Period-Luminosity-Metallicity (PLZ) and Period-Wesenheit-Metallicity (PWZ) relations for a large sample of Galactic RR Lyrae at optical and infrared wavelengths; (2) use the calibrated RR Lyrae PLZ and PWZ relations to precisely measure Galactic globular clusters' distances and calibrate globular clusters' distance scale estimators, enabling new fundamental tests of stellar evolution and stellar population models; and (3) validate the observational PLZ and PWZ relations against recently developed nonlinear, time-dependent, convective, hydrodynamic models of RR Lyrae stars calculated for a broad range of metal abundances. The investigators have demonstrated their ability to perform these measurements by completing the analysis of two of the target clusters. The investigators have all the data and models crucial to this project.

研究人员将分析一类特殊的变星的亮度变化，称为RR Lyrics星。 这些脉动恒星在银河系和其他星系中发现的古老恒星团中非常常见。 这些恒星很重要，因为它们可以被用来作为尺度来测量数千到数百万光年的距离。 距离是利用它们的变化周期（这些恒星通过亮度变化循环的时间）和它们的内在光度之间的关系来测量的。 这种“周期-光度”关系使它们成为理想的“标准蜡烛”。“研究人员将使用RR Lyrics恒星更好地校准整个宇宙的距离测量。 需要精确的距离来更好地了解宇宙的膨胀率和年龄。 他们还希望更好地理解恒星的物理学和发现RR型天琴座恒星的星团。爱荷华州州立大学物理天文学系与当地社区开展了许多外展活动。 特别是学生经营的天文馆表演，吸引了所有年龄段的大批人群，每月向公众以及当地K-12学校（艾姆斯和附近学区的40，000多名学生）提供。 该项目将重新配置以前位于菲克天文台设施（现已停产）校外的望远镜设备，使其作为新的校园内轮椅无障碍观测站的一部分提供给公众，以开展外联活动（例如，星星和太阳党后，天文馆显示为公众和K-12学生）。 他们还将为天文馆的展览准备两个新的模块，这两个模块是基于变星科学和宇宙学距离尺度的，作为向当地社区传达联邦资助的研究的一个例子，该研究是在爱荷华州州立大学完成的。自从亨里埃塔莱维特在1908年发现造父变星周期-亮度关系以来，脉动星一直是一个宝贵的距离估算器。 在这一突破性的结果之后的世纪，造父变星仍然是一个更加复杂的宇宙距离阶梯的基石。 然而，普朗克使命的最新结果揭示了从宇宙背景辐射研究中得出的宇宙学参数值与仍然主要依赖造父变星的“直接”测量值之间的一些紧张关系。 通过这个项目，研究人员的目标是提供一种替代的星族II恒星距离估计器，该估计器基于新发现的RR Lyrics变量的周期光度关系和盖亚航天器的高精度视差的可用性。 研究人员将（1）在光学和红外波长上校准银河系RR型天琴座的大样本的周期-亮度-金属丰度（PLZ）和周期-Weseneirs-金属丰度（PWZ）关系;（2）利用校正后的RR Lyrics PLZ和PWZ关系精确测量球状星团的距离，并校正球状星团的距离尺度估计值，使新的基本测试的恒星演化和恒星人口模型;（3）验证观测PLZ和PWZ的关系，对最近开发的非线性，时间依赖性，对流，流体动力学模型的RR天琴座恒星计算的广泛的金属丰度。 研究人员通过完成对两个目标集群的分析，证明了他们进行这些测量的能力。 研究人员拥有对该项目至关重要的所有数据和模型。

项目成果

On the Use of Field RR Lyrae as Galactic Probes. III. The α-element Abundances*

关于使用 Field RR Lyrae 作为银河探测器。

• DOI: 10.3847/1538-4357/abfa23
• 发表时间: 2021
• 期刊: The Astrophysical Journal
• 作者: Crestani, J.;Braga, V. F.;Fabrizio, M.;Bono, G.;Sneden, C.;Preston, G.;Ferraro, I.;Iannicola, G.;Nonino, M.;Fiorentino, G.
• 通讯作者: Fiorentino, G.

On the Use of Field RR Lyrae as Galactic Probes. V. Optical and Radial Velocity Curve Templates

• DOI: 10.3847/1538-4357/ac1074
• 发表时间: 2021-07
• 期刊: The Astrophysical Journal
• 作者: V. Braga;J. Crestani;M. Fabrizio;G. Bono;G. Preston;C. Sneden;J. Storm;S. Kamann;M. Latour;H. Lala;B. Lemasle;Z. Prudil;G. Altavilla;B. Chaboyer;M. Dall’ora;I. Ferraro;C. Gilligan;G. Fiorentino;G. Iannicola;L. Inno;S. Kwak;M. Marengo;S. Marinoni;P. Marrese;C. Martínez-Vázquez;M. Monelli;J. Mullen;N. Matsunaga;J. Neeley;P. Stetson;E. Valenti;M. T. I. A. D. Roma;M. Catone;Italy.;S. Center;Roma;D. D. Astronomia-D.;Universidade Federal do Rio Grande do Sul-Universidade-Federal-do-Rio-Grande-do-Sul-102904658;P. Alegre;Brazil.;D. Fisica;Universita' di Roma Tor Vergata;The Observatories of the Carnegie Institution for Science-The-Observatories-of-the-Carnegie-Institution-for-102218800;Pasadena;Ca;Usa;D. Astronomy;M. Observatory;The University of Texas;Austin;Tx;L. I. A. Potsdam;Potsdam;H Germany;A. R. Institute;Liverpool John Moore's University;Liverpool;UK.;Institute for Theoretical Astrophysics;Georg-August-Universitat Gottingen;A. Rechen-Institut;Zentrum fur Astronomie der Universitat Heidelberg;Heidelberg;Universit'e de Nice Sophia-antipolis;Cnrs;Observatoire de la Côte d'Azur;Laboratoire Lagrange;Nice;France;D. Physics;Astronomy;Dartmouth College;Hanover;I. -. Capodimonte;Napoli;Universita degli Studi di NapoliParthenope'';I. S. University;Ames;Ia;Cerro Tololo Inter-American Observatory;NSF's National Optical-Infrared Astronomy Research Laboratory-NSF's-National-Optical-Infrared-Astronomy-Research-1753670520;L. Serena;Chile.;Instituto de Astrof'isica de Canarias-Instituto-de-Astrof'isica-de-Canarias-102997450;La Laguna;Tenerife;Spain.;T. U. O. Tokyo;Tokyo;Japan.;Florida Atlantic University;Boca Raton;Fl;H. Astronomy;Astrophysics;National Research Council;Victoria;Bc;Canada;E. Observatory;G. B. Munchen;Instituto Milenio de Astrof'isica;Santiago;P. U. C. D. Chile;Instituto Milenio de Astrofisica

Standard Galactic field RR Lyrae II: a Gaia DR2 calibration of the period–Wesenheit–metallicity relation

• DOI: 10.1093/mnras/stz2814
• 发表时间: 2019-10
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: J. Neeley;M. Marengo;W. Freedman;B. Madore;R. Beaton;D. Hatt;Taylor J. Hoyt;A. Monson;J. Rich;A. Sarajedini;M. Seibert;V. Scowcroft

Metallicities from high-resolution spectra of 49 RR Lyrae variables

• DOI: 10.1093/mnras/stab857
• 发表时间: 2021-03
• 作者: C. Gilligan;B. Chaboyer;M. Marengo;J. Mullen;G. Bono;V. Braga;J. Crestani;M. Dall’ora;G. Fiorentino;M. Monelli;J. Neeley;M. Fabrizio;C. Mart'inez-V'azquez;F. Th'evenin;C. Sneden

Metallicity of Galactic RR Lyrae from Optical and Infrared Light Curves. I. Period–Fourier–Metallicity Relations for Fundamental-mode RR Lyrae

• DOI: 10.3847/1538-4357/abefd4
• 发表时间: 2021-03
• 期刊: The Astrophysical Journal
• 作者: J. Mullen;M. Marengo;C. Martínez-Vázquez;J. Neeley;G. Bono;M. Dall’ora;B. Chaboyer;F. Th'evenin-F.-Th'e