Astronomers have discovered an exoplanet evaporating at a rate faster than ever observed before. The exoplanet, called GJ 3470b, sits in the Cancer constellation, and was found by an international team of astronomers using the Hubble Space Telescope.
So far, most of the exoplanets discovered by astronomers are either hot Jupiter-sized planets or hot super-Earths (with diameters no more than 1.5 times the diameter of Earth). These planets are hot because they are located very close to their host star. Astronomers have rarely found a hot Neptune-sized exoplanet with size falling somewhere in between Jupiter and Earth.
But, GJ 3470b is a rare "warm Neptune." It is about 4.3 times as big as the Earth and is located about 3.7 million miles from its star. Scientists estimate that GJ 3470b has already lost up to 35 per cent of its mass over its lifetime, and it is still losing up to 10 billion grams of material every second.
A few years back, astronomers had discovered another "warm Neptune", called GJ 436b, whose rate of evaporation was 100 times less than that of GJ 3470b.
"GJ 3470b is losing more of its mass than any other planet we seen so far; in only a few billion years from now, half of the planet may be gone," said David Sing, co-author of the paper and Bloomberg Distinguished Professor at Johns Hopkins University.
GJ 3470b lies at "the edge of the evaporation desert," receiving intense radiation from its host star. These radiations heat its atmosphere to such a point that a massive cloud of gas is formed around the exoplanet. This cloud eventually escapes into the space, causing the atmosphere to shrink like a deflating balloon.
According to the research team, GJ 3470b is evaporating faster than GJ 436b. One reason for this faster evaporation rate could be its lower density, which makes GJ 3470b "less able to gravitationally hang on to the heated atmosphere."
Moreover, the host star of GJ 3470b is younger than the host star of GJ 436b, meaning GJ 3470b receives much more radiation than GJ 436b.
The study was conducted as part of the Panchromatic Comparative Exoplanet Treasury (PanCET) programme, which uses NASA's Hubble Space Telescope to measure the atmospheres of 20 exoplanets in ultraviolet, optical and infrared light.
The findings of the study are published in the Journal of Astronomy & Astrophysics.
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