Neptune-Like Exoplanet Evaporates 100 Times Faster Into The Universe’s Dark Graveyard


A continuing quest to understand the fate of exoplanets leads astronomers to discover a planet, similar to Neptune's size, that quickly evaporates into its own demise.

Scientists believe that the lifespan of planets depends on the distance and speed at which they orbit their respective stars. Recent findings published in the journal Astronomy and Astrophysics showed that GJ 3470b is vanishing 100 times faster than a similar medium-sized exoplanet, GJ 436b.

PanCET Study

The study is part of the ongoing Panchromatic Comparative Exoplanet Treasury (PanCET), which is the largest exoplanet observation program using NASA's Hubble Space Telescope. It aims to measure the atmospheric chemistry of cloud or haze formation and atmospheric mass loss of 20 exoplanets.

"GJ 3470b is losing more of its mass than any other planet we've seen so far; in only a few billion years from now, half of the planet may be gone," said lead author David Sing, who is also a Bloomberg Distinguished Professor at Johns Hopkins University.

Sing added that what they found is scientific evidence that planets far away from the solar system can lose a significant portion of their entire mass.

Planets like super-Earths and hot Jupiters have shorter distances to their host stars. The relatively high temperatures of those cause the outermost layers of their atmospheres to strip off due to evaporation. GJ 3470b's host star is only 2 billion years old, which means that it is more energetic and has a greater blistering effect on the planet's less dense atmosphere.

Neptune-sized exoplanets, which are four times the size of Earth, are rare to find. Astronomers are only able to study them in UV light, which limits their capability to examine stars further than 150 light-years away from Earth.

Fate Of Exoplanets

The discovery of GJ 3470b and GJ 436b evaporating atmospheres helped the scientists to continually understand what happens to planets in distant worlds. Their hypothesis is that mini-Neptunes or those with hydrogen-dominated atmospheres are likely to downsize to become super-Earths.

"This sizable mass loss has major consequences for its evolution, and it impacts our understanding of the origin and fate of the population of exoplanets close to their stars," said lead researcher Vincent Bourrier, of the University of Geneva in Sauverny, Switzerland.

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