Astronomers Spot Helium Cloud round Exo-Neptune HAT-P-11b


A global staff of astronomers has detected helium escaping from the higher ambiance of HAT-P-11b, a Neptune-mass exoplanet positioned within the constellation of Cygnus, about 122 light-years away. The inert gasoline is in an prolonged cloud that’s escaping from HAT-P-11b, simply as a helium balloon would possibly escape from an individual’s hand.

An artist’s impression of the exoplanet HAT-P-11b with its extended helium atmosphere blown away by the star, an orange dwarf star smaller, but more active, than the Sun. Image credit: Denis Bajram.

An artist’s impression of the exoplanet HAT-P-11b with its prolonged helium ambiance blown away by the star, an orange dwarf star smaller, however extra lively, than the Solar. Picture credit score: Denis Bajram.

Found in 2009, HAT-P-11b is about Four occasions the radius of Earth and about 26 occasions Earth’s mass.

The enormous planet orbits very near its host star, a Okay-type star known as HAT-P-11, and subsequently is extremely scorching, with temperatures round 1,100 levels Fahrenheit (605 levels Celsius).

Utilizing the Carmenes spectrograph on the Four-m telescope at Calar Alto in Spain, College of Geneva astronomer Romain Allart and co-authors detected helium atoms and measured their pace within the higher ambiance of HAT-P-11b.

“We suspected that its shut proximity to the star might influence the ambiance of the exoplanet,” Allart mentioned.

“These new observations are so exact that the exoplanet ambiance is undoubtly inflated by the stellar radiation and escapes to house.”

This artist's concept shows what the sky may look like on the exoplanet HAT-P-11b. Image credit: NASA / JPL-Caltech.

This artist’s idea exhibits what the sky could appear like on the exoplanet HAT-P-11b. Picture credit score: NASA / JPL-Caltech.

The observations are supported by a state-of-the-art pc simulation used to trace the trajectory of helium atoms.

“Helium is blown away from the day facet of the planet to its night time facet at over 6,200 mph (10,000 km an hour),” mentioned Dr. Vincent Bourrier, an astronomer on the College of Geneva.

“As a result of it’s such a light-weight gasoline, it escapes simply from the attraction of the planet and kinds an prolonged cloud throughout it.”

“It’s this phenomenon that makes HAT-P-11b so inflated, like a helium balloon.”

“This can be a actually thrilling discovery, notably as helium was solely detected in exoplanet atmospheres for the primary time earlier this 12 months,” mentioned Dr. Jessica Spake, an astronomer on the College of Exeter.

“The observations present helium being blasted away from the planet by radiation from its host star.”

“Hopefully we will use this new research to study what sorts of planets have massive envelopes of hydrogen and helium, and the way lengthy they’ll maintain the gases of their atmospheres.”

The findings had been revealed within the journal Science.


R. Allart et al. Spectrally resolved helium absorption from the prolonged ambiance of a heat Neptune-mass exoplanet. Science, revealed on-line December 6, 2018; doi: 10.1126/science.aat5879

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