A SHORT-PERIOD CENSOR OF SUB-JUPITER MASS EXOPLANETS WITH LOW DENSITY

作者：Szabo Gy M^*; Kiss L L

来源：Astrophysical Journal Letters, 2011, 727(2): L44.

DOI：10.1088/2041-8205/727/2/L44

• planets and satellites: general

Despite the existence of many short-period hot Jupiters, there is not one hot Neptune with an orbital period less than 2.5 days. Here, we discuss a cluster analysis of the currently known 106 transiting exoplanets to investigate a possible explanation for this observation. We find two distinct clusters in the mass-density space, one with hot Jupiters with a wide range of orbital periods (0.8-114 days) and a narrow range of planet radii (1.2 +/- 0.2 R-J) and another one with a mixture of super-Earths, hot Neptunes, and hot Jupiters, exhibiting a surprisingly narrow period distribution (3.7 +/- 0.8 days). These two clusters follow strikingly different distributions in the period-radius parameter plane. The branch of sub-Jupiter mass exoplanets is censored by the orbital period at the large-radius end: no planets with mass between 0.02 and 0.8 M-J or with radius between 0.25 and 1.0 R-J are known with P-orb < 2.5 days. This clustering is not predicted by current theories of planet formation and evolution, which we also review briefly.

• 出版日期2011-2-1