Stassun Keivan G, Mathieu Robert D, Cargile Phillip A, Aarnio Alicia N, Stempels Eric, Geller Aaron
Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Nature. 2008 Jun 19;453(7198):1079-82. doi: 10.1038/nature07069.
The mass and chemical composition of a star are the primary determinants of its basic physical properties-radius, temperature and luminosity-and how those properties evolve with time. Accordingly, two stars born at the same time, from the same natal material and with the same mass, are 'identical twins,' and as such might be expected to possess identical physical attributes. We have discovered in the Orion nebula a pair of stellar twins in a newborn binary star system. Each star in the binary has a mass of 0.41 +/- 0.01 solar masses, identical to within 2 per cent. Here we report that these twin stars have surface temperatures differing by approximately 300 K ( approximately 10 per cent) and luminosities differing by approximately 50 per cent, both at high confidence level. Preliminary results indicate that the stars' radii also differ, by 5-10 per cent. These surprising dissimilarities suggest that one of the twins may have been delayed by several hundred thousand years in its formation relative to its sibling. Such a delay could only have been detected in a very young, definitively equal-mass binary system. Our findings reveal cosmic limits on the age synchronization of young binary stars, often used as tests for the age calibrations of star-formation models.
恒星的质量和化学成分是其基本物理性质（半径、温度和光度）以及这些性质如何随时间演化的主要决定因素。因此，两颗同时诞生、来自相同原始物质且质量相同的恒星是“同卵双胞胎”，因此可以预期它们具有相同的物理属性。我们在猎户座星云的一个新生双星系统中发现了一对恒星双胞胎。双星中的每颗恒星质量为0.41±0.01个太阳质量，相差不到2%。在此我们报告，这两颗双胞胎恒星的表面温度相差约300K（约10%），光度相差约50%，两者都具有高置信度。初步结果表明，这两颗恒星的半径也相差5%-10%。这些惊人的差异表明，其中一颗双胞胎恒星相对于其同胞在形成过程中可能延迟了几十万 年。这样的延迟只有在非常年轻、质量绝对相等的双星系统中才能被检测到。我们的发现揭示了年轻双星年龄同步的宇宙极限，而年轻双星常被用作恒星形成模型年龄校准的测试。
