There’s a warm Neptune?

Meet HAT-26b, an exoplanet 437 light years away from the Sun. Yeah, there’s loads of exoplanets in the Milky Way, so what makes this one so important? Well since you ask, it’s incredibly interesting because it’s just like Neptune in size and looks, but it’s much warmer as it’s a whole lot closer to the star that it orbits. The discovery also shows strong signs of HAT-26b containing water but it’s not a water world like some other exoplanets could potentially be.

Why is HAT-26b important?  The discovery of this huge exoplanet shows that gas giants and ice giants like Jupiter, Saturn, Uranus and Neptune have the ability to form nearer to a star that previously believed. HAT-26b is much closer than any of these planets to its host star, which makes it that much more rare. Two other giant exoplanets that have been found elsewhere in the galaxy, HAT-P-11b and WASP-43b, are both gas giants but like their equivalents in our solar system, are not particularly close to their star.

To study the exoplanet’s atmosphere, astronomers used the Hubble telescope and waited until HAT-26b passed in front of its star. Some of the light from the star is absorbed by the planet, which reveals the chemical composition of the planet’s atmosphere. The visible and infrared wavelengths showed evidence of water as well as an abundance of heavy metals, but much less than Neptune has. Overall, this is fascinating news as scientists look further into the various origin stories of the solar systems in the Milky Way, which will eventually help put our own solar system into the context of the entire galaxy.


Cover image credit: NASA/GSFC


For more information on Neptune, check out our complete two-page guide from way back in issue 7!

Warm Neptune HAT-26b

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