In space, there is one very exotic class of exoplanets. Scientists call them “hot Neptune”. They are so rare that among 3869 confirmed worlds had been discovered only a few such planets. However, their rarity may be able to explain the recent discovery made by an international team of astronomers. This discovery is called Gliese 3470 b. This exoplanet has an interesting feature – it evaporates with incredibly high speed. On their observations, the scientists reported in the journal Astronomy & Astrophysics.
Opening ekzoplanety contributes to the hypothesis that such a small number of well-known hot Neptune may be due to the fact that in reality, planets of this class turn into miniature is one of the most widely used classes of exoplanets discovered by the telescope “Kepler”.
A hot Neptune is a giant planet the size and mass comparable to Neptune or Uranus, however, being much closer to the parent star (at a distance, even less than the distance between the earth and the Sun). In addition, as the name implies, these planets are very hot — its atmospheric temperature is approximately 927 degrees Celsius.
There are other “naturopathie” of the planet, but usually they are much further from their stars. So we face the conundrum of either a hot Neptune – are very rare in themselves or they appear as normal, but then disappear somewhere. And maybe they turn into something else, as follows from the findings of the latest research.
In General, Gliese 3470 b is not the first discovered planet with a steamy atmosphere. For example, a few years ago was discovered Gliese 436 b, which is also evaporated, but not at such a high speed. An international team of astronomers in the new study notes that the “new” planet, though it is approximately the same distance from the parent star, like Gliese 436 b, but is much hotter and evaporates 100 times faster. And if this continues further, then Gliese 3470 b sooner or later turn into mininatur or even super-earths, say scientists.
“Gliese 3470 b is losing mass much faster than any other we have seen previously on the planet. Just a few billion years, half of this planet can disappear,” — said the physicist David Singh of Johns Hopkins University and one of the authors of the study.
Both planets (Gliese 436 b and Gliese 3470 b) revolve about 6 million kilometers from their parent stars (1/10 of the distance between the Sun and mercury). Gliese 436 b orbits old stars class red dwarf, but more cold and stable between the ages of four to eight billion years. Gliese 3470 b also rotates around a red dwarf, but more young – its age is about two billion years. The star is hotter and less stable. Thus, Gliese 3470 b is subjected to a much more powerful stellar radiation, which leads eventually to a rapid loss of atmosphere.
In addition, despite the fact that the planets have comparable sizes, Gliese 3470 b has a lower density compared to Gliese 3470 b. Thus, its force of gravity holding the atmosphere are less pronounced in comparison with the latter. This observation suggests that the level of atmospheric evaporation in the case of the hot Neptune can be one of the crucial values in the fact that these planets are not so much.
In the future, the researchers hope to further study the data of extrasolar planets using future space telescope “James Webb”, which is scheduled to be launched in 2021.
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