探测附近热海王星GJ 436 b的凌日
Detection of transits of the nearby hot Neptune GJ 436 b
摘要：
这封信报告了对海王星质量的行星围绕附近的M矮星GJ 436运行的光度检测。它是迄今为止探测到的距离最近、体积最小、质量最小的凌日行星。它的质量比海王星稍大，M = 22.6 +-1.9 M地球。凌日光变曲线的形状和深度表明，它正穿过其边缘附近的主星盘（碰撞参量0.84 +-0.03），行星大小与天王星和海王星相当，R = 25200 +-2200 km = 3.95 +-0.35 R_地球。因此，它的主要成分很可能是水冰。如果目前的行星结构模型是正确的，那么在冰的顶部可能需要一层质量高达10%的H/He外层来解释观测到的半径。
英文摘要：
This Letter reports on the photometric detection of transits of the Neptune-mass planet orbiting the nearby M-dwarf star GJ 436. It is by far the closest, smallest and least massive transiting planet detected so far. Its mass is slightly larger than Neptune's at M = 22.6 +- 1.9 M_earth. The shape and depth of the transit lightcurves show that it is crossing the host star disc near its limb (impact parameter 0.84 +- 0.03) and that the planet size is comparable to that of Uranus and Neptune, R = 25200 +- 2200 km = 3.95 +- 0.35 R_earth. Its main constituant is therefore very likely to be water ice. If the current planet structure models are correct, an outer layer of H/He constituting up to ten percent in mass is probably needed on top of the ice to account for the observed radius.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
