南洋杉计划造父变星的近红外光度测量与玉夫座星系NGC 7793的距离
The Araucaria Project. The Distance to the Sculptor Group Galaxy NGC 7793 from Near-Infrared Photometry of Cepheid Variables
摘要：
在较早的发现经典造父变星在玉夫座群螺旋星系NGC 7793从光学宽视场成像调查，我们已经进行了深近红外$J$ -和$K$ -波段跟踪测光这些造父变星的子样本，以获得更高的精度比什么是可能的，从光学测光，通过最小化变红和金属含量对距离结果的影响。结合我们新的近红外周期光度关系和以前的光学光度测量，我们得到了NGC 7793的真实距离模数为$(27.66 \pm 0.04)$ mag（统计）$\pm 0.07$ mag（系统），即距离为$(3.40 \pm 0.17)$ Mpc。我们还确定影响造父变星的平均变红是$E(B-V)=(0.08 \pm 0.02)$等，表明有显着的尘埃消光固有的星系除了小的前景消光。新的，改进的造父变星距离的比较，早期的距离测定NGC 7793从塔利-费舍尔和TRGB方法产生的协议内报告的不确定性，这些以前的测量。
英文摘要：
Following the earlier discovery of classical Cepheid variables in the Sculptor Group spiral galaxy NGC 7793 from an optical wide-field imaging survey, we have performed deep near-infrared $J$- and $K$-band follow-up photometry of a subsample of these Cepheids to derive the distance to this galaxy with a higher accuracy than what was possible from optical photometry alone, by minimizing the effects of reddening and metallicity on the distance result. Combining our new near-infrared period-luminosity relations with the previous optical photometry we obtain a true distance modulus to NGC 7793 of $(27.66 \pm 0.04)$ mag (statistical) $\pm 0.07$ mag (systematic), i.e. a distance of $(3.40 \pm 0.17)$ Mpc. We also determine the mean reddening affecting the Cepheids to be $E(B-V)=(0.08 \pm 0.02)$ mag, demonstrating that there is significant dust extinction intrinsic to the galaxy in addition to the small foreground extinction. A comparison of the new, improved Cepheid distance to earlier distance determinations of NGC 7793 from the Tully-Fisher and TRGB methods yields agreement within the reported uncertainties of these previous measurements.
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