论文标题
碳星作为标准蜡烛：ii。中位j幅度作为距离指示器
Carbon stars as standard candles: II. The median J magnitude as a distance indicator
论文作者
论文摘要
我们使用富含碳的渐近巨型分支星（CS）作为标准蜡烛，以及大型和小的麦哲伦云（LMC和SMC）作为基本校准器引入了一种新的距离测定方法。我们从（$（j-k_ {s}）_ 0 $，$ j_0 $）颜色图表中选择CS的样本，因为在过滤器的这种组合中，CS明亮且易于识别。我们使用修改的Lorentzian分布来拟合CS $ J $ -BAND光度函数，以使其不对称。我们使用最佳拟合分布的参数来确定给定星系的CS亮度函数是否类似于LMC或SMC的CS。基于这种相似之处，我们使用LMC或SMC作为校准器，并使用CS样本的中位数$ J $幅度（$ \ overline {J} $）估算给定星系的距离。我们将此新方法应用于两个本地组星系NGC 6822和IC 1613。我们发现NGC 6822具有“ LMC样” CS亮度函数，而IC 1613更为“ SMC样”。使用论文中发现的LMC和SMC的中值绝对$ J $幅度的值，我们找到了$μ__{0} = 23.54 \ pm0.03 $（stat）的NGC 6822和$μ__{0} = 24.34 \ pm0.05 $（act）的NGC 6822和$μ__{0}的距离模量。
We introduce a new distance determination method using carbon-rich asymptotic giant branch stars (CS) as standard candles and the Large and Small Magellanic Clouds (LMC and SMC) as the fundamental calibrators. We select the samples of CS from the ($(J-K_{s})_0$, $J_0$) colour-magnitude diagrams, as, in this combination of filters, CS are bright and easy to identify. We fit the CS $J$-band luminosity functions using a Lorentzian distribution modified to allow the distribution to be asymmetric. We use the parameters of the best-fit distribution to determine if the CS luminosity function of a given galaxy resembles that of the LMC or SMC. Based on this resemblance, we use either the LMC or SMC as the calibrator and estimate the distance to the given galaxy using the median $J$ magnitude ($\overline{J}$) of the CS samples. We apply this new method to the two Local Group galaxies NGC 6822 and IC 1613. We find that NGC 6822 has an "LMC-like" CS luminosity function while IC 1613 is more "SMC-like". Using the values for the median absolute $J$ magnitude for the LMC and SMC found in Paper I we find a distance modulus of $μ_{0}=23.54\pm0.03$ (stat) for NGC 6822 and $μ_{0}=24.34\pm0.05$ (stat) for IC 1613.
