Discoverers of a fourth body orbiting nearby star call it hard to explain
Astronomers who previously imaged three giant planets around a single star have once again hit the jackpot by finding a fourth large body in the star system. More massive than Jupiter, the newly discovered planet lies considerably closer to the nearby star HR 8799 than the other three planets, raising questions about how all four giants formed.
The planet’s discoverers think so at least. But some other researchers disagree, saying that the situation may not be all that difficult to explain with current planet formation theories.
The star HR 8799 and its planetary retinue lie just 130 light-years from Earth. Captured in a series of telescope images over 15 months, the newly found planet lies about 14.5 astronomical units from its sun. That puts the planet about midway between where Saturn and Uranus sit in the solar system and much closer than its three companions, which the team unveiled two years ago (SN: 12/6/08, p