发表机构
NSF NOIRLab; University of North Florida; Vanderbilt University; Florida State University; Università di Roma Tor Vergata; INAF – Osservatorio Astronomico di Roma; INFN Sezione di Roma; INAF – Osservatorio Astronomico di Abruzzo; INFN, Sezione di Pisa; Dartmouth College（美国国家光学红外天文研究实验室; 北佛罗里达大学; 范德堡大学; 佛罗里达州立大学; 罗马托尔维加塔大学; 意大利国家天体物理研究所罗马天文台; 意大利国家核物理研究所罗马分部; 意大利国家天体物理研究所阿布鲁佐天文台; 意大利国家核物理研究所比萨分部; 达特茅斯学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用OGLE和WISE数据及盖亚DR3视差校准了天琴座RR型变星新的PLZ/PWZ关系，提供与食双星高度一致的麦哲伦云距离，并发现LMC中两个不同的RRL族群，为精确距离测量提供了新工具。
AI 中文摘要
天琴座RR型（RRL）变星，由于其周期-光度关系的存在，已被广泛用作银河系及本星系群内的主要标准烛光。在本工作中，我们提出了最新的经验性RRL周期-光度-金属丰度（PLZ）和周期-Wesenheit-金属丰度（PWZ）关系，结合光学（$V, I$）和中红外数据（$W1$），使用OGLE和WISE测光数据，并以盖亚DR3视差为基准。我们利用最大、最完整且均匀的银晕场RRL光谱金属丰度星表来校准这些关系。这些新的PLZ/PWZ关系提供的距离测量值与从大麦哲伦云和小麦哲伦云（MC）中的食双星推导出的距离值高度一致：$(m-M)_{0, LMC} = 18.47 \pm 0.07 (stat) \pm 0.05 (sys)$ mag 和 $(m-M)_{0, SMC} = 18.87 \pm 0.09 (stat) \pm 0.06 (sys)$ mag（分别与食双星距离的偏差在1%和10%以内）。我们还重新校准了测光金属丰度关系，以推导LMC和SMC中RRL星的个体[Fe/H]丰度。这使我们得以研究麦哲伦云的金属丰度梯度，并发现LMC中存在两个不同的基模RRL星族群（而在SMC中仅发现一个）。我们新推导的中红外周期-光度关系有望成为推导本星系群中较老恒星族群精确距离的重要工具，并且可以轻松适应于JWST NIRCam测光波段所获得的观测数据。
英文摘要
RR Lyrae (RRL) stars, thanks to the existence of their period-luminosity relations, have been widely used as primary standard candles within the Milky Way and the Local Group of galaxies. We present in this work the latest empirical RRL period-luminosity-metallicity (PLZ) and period-Wesenheit-metallicity (PWZ) relations combining optical ($V, I$) and mid-infrared data ($W1$) using OGLE and WISE photometry, anchored to Gaia DR3 parallaxes. We calibrate these relations with the largest, most complete, and homogeneous catalog of Galactic halo field RRL spectroscopic metallicities. These new PLZ/PWZ relations provide distance measurements in remarkable agreement with those derived from eclipsing binaries in the Large and Small Magellanic Clouds (MC): $(m-M)_{0, LMC} = 18.47 \pm 0.07 (stat) \pm 0.05 (sys)$ mag and $(m-M)_{0, SMC} = 18.87 \pm 0.09 (stat) \pm 0.06 (sys)$ mag (within 1% and 10% of eclipsing binary distances, respectively). We have also re-calibrated photometric metallicity relations to derive individual [Fe/H] abundances of LMC and SMC RRL stars. This allowed us to investigate the metallicity gradient of the MCs and discover two distinct populations of fundamental mode RRL stars in the LMC (only one is instead found in the SMC). Our newly derived mid-infrared period-luminosity relations are poised to become an essential tool to derive precise distances of older stellar populations in the Local Group of galaxies, and can easily be adapted to observations obtained in JWST NIRCam photometric bands.
Comments24 pages, 10 figures, 8 tables. Submitted to ApJ
