The same frequency of planets inside and outside open clusters of stars

Article

关键词: INTERMEDIATE-MASS STARS;    KEPLER;    SYSTEMS;    ISOCHRONES;    DYNAMICS;   

DOI  :  10.1038/nature12279

来源: SCIE

【 摘 要 】

Most stars and their planets form in open clusters. Over 95 per cent of such clusters have stellar densities too low (less than a hundred stars per cubic parsec) to withstand internal and external dynamical stresses and fall apart within a few hundred million years(1). Older open clusters have survived by virtue of being richer and denser in stars (1,000 to 10,000 per cubic parsec) when they formed. Such clusters represent a stellar environment very different from the birthplace of the Sun and other planet-hosting field stars. So far more than 800 planets have been found around Sun-like stars in the field(2). The field planets are usually the size of Neptune or smaller(3-5). In contrast, only four planets have been found orbiting stars in open clusters(6-8), all with masses similar to or greater than that of Jupiter. Here we report observations of the transits of two Sun-like stars by planets smaller than Neptune in the billion-year-old open cluster NGC6811. This demonstrates that small planets can form and survive in a dense cluster environment, and implies that the frequency and properties of planets in open clusters are consistent with those of planets around field stars in the Galaxy.

【 授权许可】

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