- One solar system with sun older than ours has five planets
- Find doubles the number of confirmed Kepler planets
- Discovery leads Nasa scientists to say galaxy is ‘positively loaded with planets of all sizes’
- One sun older than ours has five planets
- Technique used could speed up space telescope’s hunt for planets
NASA’s Kepler space telescope has discovered 11 new planetary systems hosting 26 confirmed planets.
It’s the latest find from a two-year space scan, and brings the total to 60 confirmed planets. The new haul triples the number of multi-planet solar systems found by Kepler.
Doug Hudgins, a Kepler scientist at Nasa says, ‘In just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets. Our galaxy is positively loaded with planets of all sizes and orbits.’
The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen are between Earth and Neptune in size.
Further observations will be required to determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune.
All the new planets are closer to their host star than Venus is to our Sun.
Kepler-33, a star that is older and more massive than our Sun, had the most planets. The system hosts five planets, ranging in size from 1.5 to 5 times that of Earth.
‘Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky,’ said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington.
Kepler identifies planet candidates by repeatedly measuring the change in brightness of stars to detect when a planet passes in front of the star. That passage casts a small shadow toward Earth and the Kepler spacecraft.
Each of the new confirmed planetary systems contains two to five closely spaced transiting planets. In tightly packed planetary systems, the gravitational pull of the planets on each other causes some planets to accelerate and some to decelerate along their orbits.
Kepler detects this effect by measuring the changes, or so-called Transit Timing Variations (TTVs).
Planetary systems with TTVs can be verified without requiring extensive ground-based observations, accelerating confirmation of planet candidates. The TTV detection technique also increases Kepler’s ability to confirm planetary systems around fainter and more distant stars.
Five of the systems (Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33) contain a pair of planets where the inner planet orbits the star twice during each orbit of the outer planet.
Four of the systems (Kepler-23, Kepler-24, Kepler-28 and Kepler-32) contain a pairing where the outer planet circles the star twice for every three times the inner planet orbits its star.
The properties of a star provide clues for planet detection. The decrease in the star’s brightness and duration of a planet transit, combined with the properties of its host star, present a recognizable signature. When astronomers detect planet candidates that exhibit similar signatures around the same star, the likelihood of any of these planet candidates being a false positive is very low.
‘The approach used to verify the Kepler-33 planets shows the overall reliability is quite high,’ said Jack Lissauer, planetary scientist at NASA Ames Research Center at Moffett Field, Calif., and lead author of the paper on Kepler-33.
These discoveries are published in four different papers in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.
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