In case you don’t know, Kepler-51 is a 500-million-year-old G-type star, that’s placed 2,615 light-years away in the constellation of Cygnus. New data from NASA, ESA, and the Hubble Space Telescope showed that Kepler-51 hosts three of the lowest density exoplanets found up until now.
Their densities are of less than 0.1 g/cm3, and they have an atmospheric scale height of 10 times larger than a typical exoplanet. Super-puffs are known to be extrasolar planets that have masses that are only a few times larger than Earth’s, their radii are more massive than Neptune, and they have very low densities.
NASA’s Kepler first discovered these planets, and they are quite rare in our galaxy. We have found less than 15 up until now.
The Kepler-51 planetary system houses a new type of exoplanet
Dr. Zachory Berta-Thompson, from the Department of Astrophysical and Planetary Sciences, from the University of Colorado, stated that the trio found by Kepler-51 “take planetary puffiness to new levels.” She also said that their discovery was contrary to what teachers tell kids in undergraduate classrooms.
Kepler-51 is also known as KOI-620, and it’s the house of Jupiter-sized planets: Kepler-51b, c and d, and their orbital periods are 45, 85 and 130 days. These planets were discovered by Kepler back in 2012, and they are several times the mass of Earth. Their atmospheres are made out of hydrogen and helium.
All of these planets have a density of less than 0.1 g/cm3 of volume, which is really surprising. Researchers have observed two transits of Kepler-51b and d with the help of Hubble’s Wide Field Camera 3. They also found the spectra of both planets that do not have any chemical signatures. This was unexpected since they wanted to take a look at large water absorption characteristics, but there is nothing to look at.