陳蕙雅思閱讀短文 - 天文家發現系外“太陽系”

兩個獨立的天文學家研究團隊可能已經確定了一個富有的行星系統，有七顆行星圍繞黃矮星KOI-351(KIC 11442793)。這是Kepler太空望遠鏡發現的行星數最多的星系統，之前是六顆行星的Kepler-11。 KOI-351位於距離地球約2,500光年，七個行星的軌道非常接近其主星，最週邊的KOI-351 b軌道和地球相似。

Astronomers may have identified one of the richest planetary systems yet.

The discovery of a seventh planet around the dwarf star KIC 11442793 could be a record, according to two separate teams of researchers.

The system bears some similarities to our own, but all seven planets orbit much closer to their host star, which lies some 2,500 light-years from Earth.

The crowded solar system is described in two papers published on the pre-print server Arxiv.org.

One of the identifications was made by volunteers using the Planet Hunters website. The site was set up to allow volunteers to sift through the public data from Nasa's Kepler space telescope - which was launched to search for so-called exoplanets - worlds orbiting distant stars.

Kepler uses the transit method to discover new planets, which entails looking for the dip in light as an alien world passes in front of its host star. But there is simply too much data for mission scientists to examine every light curve, so they developed computer programmes to search for the signature of a planetary transit.

"This is the first seven-planet system from Kepler, using a transiting search. We think [the identification] is very secure," said Chris Lintott, from the University of Oxford, co-author on the Planet Hunters paper.

"With a transiting system, once you get multiple planets, the odds of them being false positives are very small."