Researchers who studied stars similar to the Sun found that almost one in four could have small, rocky planets just like the Earth。
For their research, scientists spent five years studying 166 Sun-like stars within 80 light year – or 470 trillion miles – of Earth。
Researcher Andrew Howard, from the University of California at Berkeley, said: "Of about 100 typical Sun-like stars, one or two have planets the size of Jupiter, roughly six have a planet the size of Neptune, and about 12 have super-Earths between three and ten Earth masses. If we extrapolate down to Earth-size planets between one-half and two times the mass of Earth, we predict that you'd find about 23 for every 100 stars."Last month, astronomers announced the discovery of the most Earth-like planet ever found – a rocky world three times the size of our own world, orbiting a star 20 light years away. The planet appears to have an atmosphere, gravity like our own – and could have flowing water on its surface。
The technique can only detect planets orbiting close to their stars. That means the true number of planets could be much higher. Over the next decade, new methods of planet detection and more powerful telescopes could soon be uncovering true Earth-like worlds orbiting distant stars, the scientists said。
据英国《每日邮报》29日报道，研究人员宣称，四分之一的类日恒星或有大小以及构成与地球相似的卫星。
研究中，科学家们用五年时间分析计算了166个距离地球80光年(470兆英里)以内的类日恒星。
来自加利福尼亚大学伯克利分校的研究员安德鲁-霍华德称：“在100个典型的类日恒星中，其中一到两个拥有的卫星和木星差不多大小，大约有六个恒星各拥有一颗和海王星等大的卫星，而拥有质量为3地球质量到10地球质量(注：地球质量是一种计量单位，1地球质量 = 5.9742 × 1024千克)的超级地球作为卫星的类日恒星约有12个。若我们考虑质量为1.5地球质量到2地球质量之间、大小同地球相同的卫星，则会发现每100个恒星中，这样的卫星就有23个。”
上月，天文学家宣称已发现最类似地球卫星——其大小为地球的三倍，表面为岩石覆盖，距离其环绕的恒星20光年。该行星似乎也拥有大气层和重力作用——其表面也可能有流水存在。
目前的探测技术只能检测到距离类日恒星较近的卫星。这便意味着环绕类日恒星的卫星数目要庞大得多。科学家称，未来10年里，新的卫星探测技术以及功能更加强大的望远镜会帮助人类解释遥远恒星周围的类地卫星的真相所在。 |