Using ultraviolet information from the NASA/ESA Hubble Space Telescope, astronomers have detected carbon ions — charged particles that work together with magnetic fields — within the magnetosphere of the Neptune-sized exoplanet HAT-P-11b and located that the metallicity of its ambiance is decrease than anticipated.
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 energetic, than the Sun. Image credit score: Denis Bajram.
HAT-P-11b is positioned roughly 122 light-years away within the constellation of Cygnus.
Discovered in 2009, the planet is 4 occasions the radius of Earth and about 26 occasions Earth’s mass.
Also often called Kepler 3b, it orbits very near its host star, the tenth magnitude Okay-type star HAT-P-11, and subsequently is extremely scorching, with temperatures round 605 levels Celsius (1,100 levels Fahrenheit).
HAT-P-11b most likely has a rocky core, wrapped in a thick, gaseous envelope of about 90% hydrogen.
“This is the first time the signature of an exoplanet’s magnetic field has been directly detected on a planet outside our Solar System,” mentioned Dr. Gilda Ballester, an astronomer on the University of Arizona Lunar and Planetary Laboratory.
“A strong magnetic field on a planet like Earth can protect its atmosphere and surface from direct bombardment of the energetic particles that make up the solar wind.”
“These processes heavily affect the evolution of life on a planet like Earth because the magnetic field shelters organisms from these energetic particles.”
Hubble’s observations of an prolonged area of charged carbon particles that encompass the exoplanet HAT-P-11b and streaming away in an extended tail are finest defined by magnetic subject, the primary such discovery on a planet exterior of our Solar System. The planet is depicted because the small circle close to the middle. Carbon ions fill an immense area it. In the magnetotail, not proven to its full extent, ions escape on the noticed common speeds of about 161,000 kmh. Image credit score: Lotfi Ben-Jaffel / Institute of Astrophysics, Paris.
Using Hubble, Dr. Ballester and colleagues noticed carbon ions not solely in a area surrounding HAT-P-11b, but in addition extending in an extended tail that streamed away from the planet at common speeds of 161,000 kmh (100,000 mph).
The tail reached into area for no less than 1 AU (astronomical unit), the space between Earth and the Sun.
The astronomers then used 3D laptop simulations to mannequin interactions between the planet’s uppermost atmospheric areas and magnetic subject with the incoming photo voltaic wind.
“Just like Earth’s magnetic field and its immediate space environment interact with the impinging solar wind, which consists of charged particles traveling at about 1.45 million kmh (900,000 mph), there are interactions between HAT-P-11b’s magnetic field and its immediate space environment with the solar wind from its host star, and those are very complex,” Dr. Ballester mentioned.
“The physics in the magnetospheres of Earth and HAT-P-11b are the same; however, the exoplanet’s close proximity to its star causes its upper atmosphere to warm and essentially ‘boil off’ into space, resulting in the formation of the magnetotail.”
The staff additionally discovered that the metallicity of HAT-P-11b’s ambiance — the variety of chemical parts in an object which might be heavier than hydrogen and helium — is decrease than anticipated.
“HAT-P-11b’s low atmospheric metallicity challenges current models of exoplanet formation,” the researchers mentioned.
“We think the exoplanet more resembles a mini-Jupiter than a Neptune.”
“The atmospheric composition we see on HAT-P-11b suggests that further work needs to be done to refine current theories of how certain exoplanets form in general.”
The new outcomes seem within the journal Nature Astronomy.
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L. Ben-Jaffel et al. Signatures of robust magnetization and a metal-poor ambiance for a Neptune-sized exoplanet. Nat Astron, revealed on-line December 16, 2021; doi: 10.1038/s41550-021-01505-x
