本帖最后由 gohomeman1 于 2010-4-10 10:05 编辑
原文摘要:
Epsilon Aurigae (ϵ Aur) is a visually bright, eclipsing binary star system with a period of 27.1 years. The cause of each 18-month-long eclipse has been a subject of controversy for nearly 190 years because the companion has hitherto been undetectable. The orbital elements imply that the opaque object has roughly the same mass as the visible component, which for much of the last century was thought to be an F-type supergiant star with a mass of ~15M⊙ (M⊙, mass of the Sun). The high mass-to-luminosity ratio of the hidden object was originally explained by supposing it to be a hyperextended infrared star or, later, a black hole with an accretion disk, although the preferred interpretation was as a disk of opaque material at a temperature of ~500 K, tilted to the line of sight and with a central opening.
柱一(御夫座ε)是明亮的食双星,互绕周期为27.1年。对它长达18个月的掩食过程,已经争论了190年之久,因为伴星迄今还没搞清。根据轨道根数,一般近似地认为不透明伴星与明亮的主星质量相当,而上世纪主流的观点认为主星是15个太阳质量左右的F型(白色)超巨星。大质量就意味着高光度,如此暗天体的早期解释是一颗大气层巨幅扩展的红外星,后来也有认为是带吸积盘的黑洞的。当然,比较合理的解释是:一个与我们视线有倾角的、中心带孔的、温度约550K(~280℃)的不透明物质环。
Recent work implies that the system consists of a low-mass (2.2M⊙–3.3M⊙) visible F-type star, with a disk at 550 K that enshrouds a single B5V-type star. Here we report interferometric images that show the eclipsing body moving in front of the F star. The body is an opaque disk and appears tilted as predicted. Adopting a mass of 5.9M⊙ for the B star, we derive a mass of ~(3.6 ± 0.7)M⊙ for the F star. The disk mass is dynamically negligible; we estimate it to contain ~0.07Mcircle plus (Mcircle plus, mass of the Earth) if it consists purely of dust.
最新的研究认为:双星系统的主星为2.2~3.3个太阳质量的F型星,伴星则是包裹在550K尘埃气体盘中的B5V型星。我们在此报告:根据干涉图像测定,掩食伴星已经移到主星前,它带有尘埃气体盘,与先前预计一样是带倾角的。我们的数据支持:伴星质量约5.9个太阳,主星质量约3.6±0.7个太阳。盘的质量可以忽略不计,我们估计如果它基本由尘埃组成,大概只有0.07个地球质量。 |