A new planet in the Kepler-51 system has been discovered by NASA's James Webb Space Telescope (JWST). The "super-puff" planets in the Kepler-51 system have densities as light as cotton candy.
The discovery was made while scientists from Osaka University and Penn State studied Kepler-51d, one of the system's three known planets that is 2,600 light-years away from Earth.
The team discovered a fourth planet, Kepler-51e, after observing anomalous gravitational effects influencing the planet's orbit.
This is the first known discovery of a planet using JWST using a technique called transit timing variations, in which the gravitational pull of one planet changes the timing of another planet's transit across its star.
Co-lead of the study and Penn State postdoctoral fellow Dr. Jessica Libby-Roberts called the Kepler-51 system "exceptional."
She stated: "The three planets that were previously known have densities so low they resemble cotton candy, and they are roughly the size of Saturn but only a few times the mass of Earth.
"Now, we've found a fourth planet, and its presence is reshaping our understanding of the system." The discovery clarifies the enigmatic Kepler-51 system, which NASA's Kepler Space Telescope initially observed.
Their enormous helium and hydrogen atmospheres, which have held up in the face of intense radiation from their young star, make the planets unique.
The newest member of the system, Kepler-51e, is thought to have an orbit of 264 days, which puts it close to the star's habitable zone.
Since it hasn't been directly seen transiting its star, scientists estimate that its mass is comparable to that of the other three planets, but they don't know its radius or density.