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(...) HAT-P-26b – located some 437 light-years away from Earth – is what's called a 'warm' or 'hot Neptune', meaning its mass is similar to Neptune, but that the planet closely orbits its host star.
(...) What's unusual about HAT-P-26b is its unexpectedly primordial atmosphere, composed almost entirely of hydrogen and helium. For a planet that hangs so close to its star – orbiting it in just 4.23 days, in fact – that breaks a pattern astronomers are used to seeing in the atmospheric composition of other planets.
(...) in the case of HAT-P-26b, we've got a world that's not far out from its host star – and is in fact virtually clinging to it – and yet its atmosphere is almost entirely composed of hydrogen and helium, much like Jupiter and Saturn.
(...) "We did not know that you could form these-sized planets closer to their star."
(...) "I would say that has been a theme in the studies of exoplanets: Researchers keep finding surprising diversity."