We present near-infrared JHK photometry for the resolved stellar populations in 13 nearby galaxies: NGC 6822, IC 1613, NGC 3109, Sextans B, Sextans A, NGC 300, NGC 55, NGC 7793, NGC 247, NGC 5253, Cen A, NGC 1313, and M83, acquired from the 6.5 m Baade–Magellan telescope. We measure distances to each galaxy using the J-region asymptotic giant branch (JAGB) method, a new standard candle that leverages the constant luminosities of color-selected, carbon-rich AGB stars. While only single-epoch, random-phase photometry is necessary to derive JAGB distances, our photometry is time-averaged over multiple epochs, thereby decreasing the contribution of the JAGB stars’ intrinsic variability to the measured dispersions in their observed luminosity functions. To cross-validate these distances, we also measure near-infrared tip of the red giant branch (TRGB) distances to these galaxies. The residuals obtained from subtracting the distance moduli from the two methods yield an rms scatter of σ _JAGB−TRGB = ±0.07 mag. Therefore, all systematics in the JAGB method and TRGB method (e.g., crowding, differential reddening, star formation histories) must be contained within these ±0.07 mag bounds for this sample of galaxies because the JAGB and TRGB distance indicators are drawn from entirely distinct stellar populations and are thus affected by these systematics independently. Finally, the composite JAGB star luminosity function formed from this diverse sample of galaxies is well described by a Gaussian function with a modal value of M _J = –6.20 ± 0.003 mag (stat), indicating that the underlying JAGB star luminosity function of a well-sampled full star formation history is highly symmetric and Gaussian based on over 6700 JAGB stars in the composite sample.

中文翻译：

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麦哲伦望远镜对 13 个附近星系的近红外恒星光度测定：J 区渐近巨分支法距离


我们提供近红外 JHK 光度测量，用于 13 个邻近星系中已解析的恒星群：NGC 6822、IC 1613、NGC 3109、Sextans B、Sextans A、NGC 300、NGC 55、NGC 7793、NGC 247、NGC 5253、Cen A、 NGC 1313 和 M83，从 6.5 m 巴德-麦哲伦望远镜获取。我们使用 J 区渐近巨星分支 (JAGB) 方法测量到每个星系的距离，这是一种新的标准蜡烛，利用了颜色选择的、富含碳的 AGB 恒星的恒定光度。虽然只有单历元、随机相位光度测量对于推导 JAGB 距离是必要的，但我们的光度测量是多个历元的时间平均，从而减少了 JAGB 恒星的固有变异性对其观测到的光度函数中测量的色散的贡献。为了交叉验证这些距离，我们还测量了红巨星分支的近红外尖端（TRGB）到这些星系的距离。从两种方法中减去距离模量获得的残差产生 σ _JAGB−TRGB = ±0.07 mag 的 rms 散布。因此，JAGB 方法和 TRGB 方法中的所有系统学（例如，拥挤、差异红化、恒星形成历史）必须包含在该星系样本的 ±0.07 星等范围内，因为 JAGB 和 TRGB 距离指标是从完全不同的恒星中提取的人口，因此独立地受到这些系统的影响。最后，由这种不同的星系样本形成的复合 JAGB 恒星光度函数可以通过模态值为 M _J = –6.20 ± 0.003 mag (stat) 的高斯函数很好地描述，表明底层的 JAGB充分采样的完整恒星形成历史的恒星光度函数是高度对称的和高斯的，基于复合样本中超过 6700 颗 JAGB 恒星。