WASP-69b (left), the column above it and its star (Image: W.M. Keck Observatory)
A few decades ago, it was questionable whether there were planets orbiting other stars at all (since the first was discovered with certainty only in 1995), but the number of known exoplanets has now risen to more than 5,500 (in 2016 alone, Nearly 1,500 of them have been discovered.) So, at present, there is not much news if they find new news. However, the planet WASP-69b private: It drags a comet-like column more than half a million kilometers long.
The exoplanet orbits a star 160 light-years away, and its column is made of helium gas. It's about the same size as Jupiter, though much lighter, and is so close to its star that it orbits in just 3.9 Earth days, so it's relatively common to celebrate the New Year on WASP-69b. Since the planet orbits close to the star, its surface is very hot: its atmosphere can reach 10,000 degrees Celsius. The solar wind constantly carries materials, such as helium, from the upper layer of the atmosphere, which expands due to heat, and this forms the tail that the planet pulls. The length of the column is one and a half times the average distance between the Earth and the Moon. The existence of a helium plume on the planet has long been suspected (the planet itself has been discovered before), but it has not yet been confirmed.
Exoplanet researchers from the University of California, Los Angeles (UCLA) analyzed images from the Keck Observatory built on the Manoa Kea volcano in Hawaii. Hence, the true length of the column and its characteristics were revealed. The results not only revealed the plume of this exoplanet, but also found an explanation for the absence of exoplanets smaller than Jupiter orbiting close to their star. Perhaps, over time, the star's radiation eroded their atmosphere to the point that they simply ran out and were destroyed. Jupiter-sized planets, on the other hand, have a large enough mass, and thus a gravitational field, to be able to retain most of their material.
WASP-69b loses 200,000 tons of material every second, but even with this staggering amount, it will be able to retain most of its mass for the rest of its star's life (i.e. it will never be completely depleted). By examining it, researchers can observe in real time how planets lose the upper layer of their atmosphere.
