PARIS: A graduate student Berkeley and his colleagues have discovered three new “exoplanets” orbiting a cool and smallish star after studying data sent back by the Kepler spacecraft that is sweeping the Milky Way in search of distant solar systems.
The smallest of the three planets is 1½ times the size of Earth and is flying around its star in the “habitable zone,” where surface temperatures are moderate enough for liquid water — like the oceans on planet Earth — to exist.
Erik Petigura, who works at Berkeley with planet seeker Geoffrey Marcy, the world’s champion planet hunter, discovered evidence of the exoplanets less than two weeks ago in the reams of computer data on light curves that Kepler has amassed since it began searching the distant skies in 1999.
Petigura’s find was immediately confirmed by ground-based telescopes in Chile, Hawaii and California. Among the telescopes was the unique Automated Planet Finder at UC’s Lick Observatory atop Mount Hamilton east of San Jose.
The Kepler telescope detects planets around distant stars by noting the faint dimming of a star’s light when an object like a planet passes across the star’s face — a passage known as “transiting.”
In this case the exoplanets’ star is known as a red M-dwarf. It is about half the size and mass of our own sun, Petigura said, and at about 150 light-years away from Earth, is near enough for other astronomers to study the planets’ atmospheres to learn whether their gases are similar to Earth’s and might conceivably support life.
A report on the new discovery has been submitted to the Astrophysical Journal by Petigura and his colleagues, Ian Crossfield of the University of Arizona and Andrew Howard of the University of Hawaii.
Kepler’s continued ability to detect new planets, Petigura said, is particularly significant because the spacecraft was disabled more than two years ago when its steering mechanism failed. At NASA’s Ames Research Center in Mountain View, the Kepler mission’s engineers developed an alternative way to keep it operating, and since then it’s been scanning the night sky on a new mission called K2:
Instead of aiming only at the two constellations, Cygnus and Lyra, Kepler is scanning the entire night sky and moving under the impulse of the sun’s powerful solar wind.
