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THE ARAUCARIA PROJECT. INFRARED TIP OF THE RED GIANT BRANCH DISTANCES TO FIVE DWARF GALAXIES IN THE LOCAL GROUP*

机译:阿劳卡里亚项目。本地小组中五个巨型星系的红色巨人分支的红外提示*

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We have obtained accurate near-infrared photometry of the tip of the red giant branch (TRGB) in the Local Group galaxies Sculptor, NGC?6822, NGC?3109, IC?1613, and WLM. We have used the derived TRGB magnitudes together with the absolute magnitude calibration of the near-infrared TRGB magnitude of Valenti et?al. to determine the distances of these five galaxies. The statistical errors in the distance moduli are typically 4%. The systematic uncertainties are dominated by the knowledge of the mean metallicities of the red giant branches and are in the range of 5%-8%. We observe a slight (2%) systematic difference between the distances derived from the J and K bands, respectively, which is within the 1σ errors of the distances. We compare the new distances derived in this paper with other recent distance determinations for our target galaxies and find excellent agreement. In particular, the near-infrared TRGB distances to the four dwarf irregular galaxies in the sample agree to better than 5% in each case with their Cepheid distances obtained from infrared photometry, indicating that there is no appreciable systematic offset between these two fundamental techniques using old and young stellar populations, respectively.
机译:我们已经获得了本地群星系Sculptor,NGC?6822,NGC?3109,IC?1613和WLM中红巨星分支(TRGB)尖端的精确近红外光度法。我们将推导的TRGB幅度与Valenti等人的近红外TRGB幅度的绝对幅度校准一起使用。确定这五个星系的距离。距离模的统计误差通常为4%。系统的不确定性主要由红色巨型分支的平均金属度的知识决定,范围为5%-8%。我们分别观察到从J波段和K波段得出的距离之间的轻微系统差异(2%),该距离在距离的1σ误差内。我们将本文得出的新距离与目标星系的其他最近距离确定进行了比较,并发现了极好的一致性。特别是,样品中四个矮小不规则星系的近红外TRGB距离在每种情况下都比通过红外光度法测得的造父变星距离好于5%,这表明使用这两种基本技术之间没有明显的系统性偏移。老年和青年恒星族分别。

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