Kepler-51 is home to three super-swollen exoplanet: Kepler-51 is a 500 million-year-old G-type star located 2,615 light years away in the constellation Cygnus. New observations from the NASA / ESA Hubble Space Telescope showed that the Kepler-51 houses three of the lowest density exoplanets known to date.
At a density of less than 0.1 g / cm3, the elevation of the atmospheric scale on these planets is 10 times greater than that of a typical hot Jupiter exoplanet. Super puffs are several times larger than Earth, planets larger than Neptune and planets of much lower density.
First discovered by NASA’s Kepler space telescope, these planets are relatively rare in our galaxy, the Milky Way: so far less than 15 have been discovered. “A trio of Kepler-51 has taken planetary disturbances to new levels,” said Dr. Zachary Berta-Thompson is an astronomer in the Department of Astronomy and Planetary Sciences at the University of Colorado, Boulder.
“Their discovery was directly opposite to what we teach in graduate classes.” Also known as KOI-620, Kepler-51 houses three planets the size of Jupiter: Kepler-51B, C and D, with an orbital period of 45, 85 and 130 days. Discovered by Kepler in 2012, these planets are several times larger than Earth’s mass and have a hydrogen / helium atmosphere.
“The three planets had a density of less than 0.1 g / cm3, almost the same as the pink candy bought at any fair,” said Jessica Libby-Roberts, an astrologer and graduate student in the Department of Planetary Sciences. University of Colorado, Boulder.
“We knew they were low density. But when you photograph a cotton candy ball in the form of Jupiter, it is really low density. ” This representation shows three massive planets orbiting Kepler-51 compared to some planets in our solar system.
Dr. Berta-Thompson, Libby-Roberts and colleagues saw two transits of the Kepler-51B with the Hubble 3 wide-field camera. The researchers found no chemical signs in the spectra of both planets. “It was completely unexpected. We had planned to see large water absorption facilities, but they weren’t there. They forced us out,” Libby-Roberts said.
“However, unlike Earth’s water clouds, clouds on these planets can be formed by salt crystals or photochemical rewards, such as those found on Saturn’s largest moon, Titan.” These clouds provide scientists with an idea of how Kepler-51B and D compare to other low mass and gas rich exoplanets.
“By comparing the flat spectra of the overpopulations with the spectra of other planets, we could support the hypothesis that the formation of clouds / mists is associated with the temperature of the planet: the colder a planet is, the deeper it becomes”, said.
“The low density of these planets is the result of the early age of the system, just 500 million years older than our Sun of 4.6 million years.” “The models suggest that these planets formed outside the star’s snow line,” areas of possible orbits where frozen matter can escape. After this, the planets went inward. “
The authors also found that Kepler-51B, C and D flow at high speed. He calculated that if this trend continued, the planets could be substantially reduced in the next billion years, increasing their frustration. Finally, they can be transmitted as a common class of exoplanets called ‘mini-neptunes‘.
“People are really struggling to discover why this system is so different from everyone else. We are trying to show, in fact, that it looks like these other systems, ”said Libby-Roberts. Dr. Berta-Thompson said: “A good fact of their rarity is that we are seeing them at a time of their evolution, where we rarely have the opportunity to see planets.”
The team article will be published in the Astronomical Journal.