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首页> 外文期刊>The Astrophysical journal >Fundamental Properties and Distances of the Large Magellanic Cloud from Eclipsing Binaries. II. HV 982*
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Fundamental Properties and Distances of the Large Magellanic Cloud from Eclipsing Binaries. II. HV 982*

机译:麦哲伦星云从爬升二进制数的基本性质和距离。二。 HV 982 *

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We have determined the distance to a second eclipsing binary (EB) system in the Large Magellanic Cloud, HV 982 (~B1 IV-V + ~B1 IV-V). The measurement of the distance—among other properties of the system—is based on optical photometry and spectroscopy and space-based UV/optical spectrophotometry. The analysis combines the "classical" EB study of light and radial velocity curves, which yields the stellar masses and radii, with a new analysis of the observed energy distribution, which yields the effective temperature, metallicity, and reddening of the system plus the distance "attenuation factor," essentially (radius/distance)2. Combining the results gives the distance to HV 982, which is 50.2 ± 1.2 kpc. This distance determination consists of a detailed study of well-understood objects (B stars) in a well-understood evolutionary phase (core H burning). The results are entirely consistent with—but do not depend on—stellar evolution calculations. There are no "zero-point" uncertainties as, for example, with the use of Cepheid variables. Neither is the result subject to sampling biases, as may affect techniques that utilize whole stellar populations, such as red giant branch stars. Moreover, the analysis is insensitive to stellar metallicity (although the metallicity of the stars is explicitly determined), and the effects of interstellar extinction are determined for each object studied. After correcting for the location of HV 982, we find an implied distance to the optical center of the LMC's bar of dLMC = 50.7 ± 1.2 kpc. This result differs by nearly 5 kpc from our earlier result for the EB HV 2274, which implies a bar distance of 45.9 kpc. These results may either reflect marginally compatible measures of a unique LMC distance or, alternatively, suggest a significant depth to the stellar distribution in the LMC. Some evidence for this latter hypothesis is discussed.
机译:我们确定了到大麦哲伦星云HV 982(〜B1 IV-V +〜B1 IV-V)中第二个日食双星(EB)系统的距离。距离的测量以及系统的其他特性是基于光学光度法和光谱学以及基于空间的UV /光学分光光度法。该分析将对光速和径向速度曲线的“经典” EB研究结合在一起,产生了恒星质量和半径,并对观测到的能量分布进行了新分析,从而得出了有效的温度,金属性,系统变红以及距离“衰减因子”,本质上(半径/距离)2。结合结果可得出到HV 982的距离为50.2±1.2 kpc。该距离确定包括对处于良好理解的演化阶段(核心H燃烧)的易于理解的物体(B星)的详细研究。结果完全与(但不取决于)恒星演化计算一致。不存在“零点”不确定性,例如,使用造父变星。结果也不会受到采样偏差的影响,因为这可能会影响利用整个恒星种群的技术,例如红色巨型分支星。此外,该分析对恒星的金属感不敏感(尽管已明确确定了恒星的金属感),并且为每个研究对象确定了星际消光的影响。校正HV 982的位置后,我们发现到LMC棒的光学中心的隐含距离dLMC = 50.7±1.2 kpc。该结果与我们先前针对EB HV 2274的结果相差近5 kpc,这意味着钢筋距离为45.9 kpc。这些结果可能反映了唯一LMC距离的边缘兼容量度,或者暗示了LMC中恒星分布的深度。讨论了后一种假设的一些证据。

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