AI discovers star with eight planets

Solar system is no longer the only known eight-system

Eight planets around a sun-like star: The Kepler-90 planetary system is the same as our solar system. © NASA / Ames Research Center / Wendy Stenzel
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Machine brain as a planet hunter: Our sun is no longer the only known star with eight planets. Around the 2, 545 light-years distant star Kepler -90 circle also eight companions. The eighth planet of this system was not discovered by a human astronomer, but by a learning artificial intelligence. In the data of the Kepler Space Telescope she has tracked down the tiny variations in light that the planet causes in transit in front of its star.

The Kepler Space Telescope is the most successful "planet hunter" astronomy possesses. Hundreds of exoplanets have already tracked this eye in space through their transits - the faint dimming of the light that the planets create when passing in front of their star. Among the Kepler discoveries are plenty of Earth twins, but above all, the sheer number of planetary discoveries has allowed astronomers to identify initial regularities - and mysterious gaps - in the planetary existence of our galaxy.

Learning machine brain as investigator

The latest discovery, however, is not from a human astronomer - it was an artificial intelligence. The enormous amount of data accumulated by the Kepler telescope brought Google AI software engineer Christopher Shallue to the point of evaluating an adaptive computer brain. "Machine learning can always shine when there's so much data that people can not search through it, " explains Shallue.

In the case of Kepler, it was about 35, 000 possible transit signals that the telescope had recorded in four years of search. For the AI ​​search, the researchers first trained their adaptive neural network on the basis of 15, 000 confirmed planetary signals. At these, the system learned which features characterize the light curve of a true planet transit until it was correct in 96 percent of the cases.

Search in foreign planetary systems

Then the real search began: The researchers let the AI ​​evaluate a dataset of 670 stars around which already planets were known. Your assumption: If these stars already have one or more planets, then there is a high probability that other, previously undiscovered companions are hiding in their vicinity. display

How Artificial Intelligence Helps Planet Search "NASA Ames

And indeed: The AI ​​has been found in several cases. "Of course, we also received many false positive results, " says Andrew Vanderburg of the University of Texas at Austin. "But this is like sifting Gerll to find gems: with a finer sieve you can find more stones, but also more gems."

An eighth planet around Kepler-90

The most exciting find was the machine brain around Kepler-90, a sun-like star about 2, 545 light-years away. Seven planets were already known in this system - all very close to their parent star. Now, the AI ​​has tracked down an eighth planet orbiting the star third from the inside Kepler-90i only takes 14.4 days to complete a round.

This Kepler -90 is the first known planetary system around a strange star, which has eight planets just like our solar system. "For the first time since the first planets of our own solar system were discovered, we now know that our solar system is not the only record holder with eight planets, " says Vanderburg.

The planetary sizes of Kepler-90 are similar to those in the solar system. NASA / Ames Research Center / Wendy Stenzel

Mini version of our solar system

The Kepler-90 Eightsystem has similarities to our own solar system as well as differences. So even with the alien star, the size of the planets grows outward: while the six inner-most planets rank between the size of a super-earth and Neptungr e, the two outer planets are big gas giants in Jupiter format.

Unlike the solar system, however, all planets are very close together: "The Kepler-90 system is like a mini version of our solar system, " explains Vanderburg. Transmitted to our system, the orbits of all eight planets were still within Earth's orbit around the sun.

Due to their close proximity to their star, the inner planets of Kepler-90 - and also the newly discovered Kepler-90i - are not very friendly to life. Temperatures of more than 400 degrees Celsius are likely to prevail on its surface, much like the daytime side of Mercury.

The search continues

In addition to the eighth planet around Kepler-90, the AI ​​has also discovered other previously undiscovered planets around other stars. The researchers want to let their learning machine brain next on an even larger record of Kepler data this time the light curves of more than 150, 000 stars.

"As we expected, there are exciting discoveries to be found in our archived Kepler data, " says Paul Hertz, director of astrophysics at NASA. "This discovery proves that our data will be a treasure chest for years to come."

(NASA Ames, 15.12.2017 - NPO)