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June 26, 2015

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Planet zips around its sun sporting comet-like tail: study 

June 26, 2015
Courtesy 
and World Science staff

A gi­ant plan­et is or­bit­ing its sun while sport­ing a comet-like tail, which con­sists of hy­dro­gen gas drift­ing away from its sur­face, ac­cord­ing to as­tro­no­mers. 

The sci­en­tists at­trib­ute the ef­fect to high-energy light from the star that is push­ing hy­dro­gen off the plan­et’s up­pe­r at­mos­phere. 

An "artistic" rendering of plan­et GJ 436b as it might look from near­by, deve­loped by study collab­orator Mark Gar­lick of the Univ­ers­ity of War­wick.


The find­ings con­cern­ing the al­ien world, about the weight of Nep­tune, are re­ported in this week’s is­sue of the re­search jour­nal Na­ture

Re­search­ers had pre­vi­ously sug­gested that small plan­ets or­bit­ing close to their par­ent stars could lose some frac­tion of their at­mos­pheres in this way, but con­fi­dent mea­sure­ments of such losses had been lack­ing, ac­cord­ing to the au­thors of the new stu­dy. 

Pe­ter Wheat­ley of the Uni­vers­ity of War­wick in the U.K. led an x-ray ob­serva­t­ion proj­ect to trace the heat­ing of the at­mos­phere of the plan­et. 

The ob­serva­t­ions, he said, re­veal “a large cloud of hy­dro­gen gas ab­sorb­ing the light from a red dwarf star as its exoplan­et, GJ 436b, passes in fron­t.” An exoplan­et is a plan­et out­side our so­lar sys­tem, and a red dwarf star is a small, rel­a­tively cool, low-burning star.

“The cloud forms a comet-like tail as a re­sult of ul­tra­vi­o­let light com­ing from the star push­ing on the hy­dro­gen and caus­ing it to spir­al out­wards,” Wheat­ley con­tin­ued.

He added that the amount of gas be­ing lost is about 1,000 met­ric tons per sec­ond, equiv­a­lent to about one-thousandth of the weight of the plan­et eve­ry bil­lion years. But “the same pro­cess is likely to be much stronger on oth­er exoplan­ets, where the en­tire at­mos­phere could be re­moved or evap­o­rat­ed to de­struc­tion.”

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A giant planet is orbiting its sun followed by a comet-like tail, which consists of hydrogen gas drifting away from its surface, according to astronomers. The scientists attribute the effect to high-energy light from the star that is pushing hydrogen off the planet’s upper atmosphere. The findings concerning the alien world, about the weight of Neptune, are reported in this week’s issue of the research journal Nature. Researchers had previously suggested that small planets orbiting close to their parent stars could lose some fraction of their atmospheres in this way, but confident measurements of such losses had been lacking, according to the authors of the new study. Peter Wheatley of the University of Warwick in the U.K. led an x-ray observation project to trace the heating of the atmosphere of the planet. The observations, he said, reveal “a large cloud of hydrogen gas absorbing the light from a red dwarf star as its exoplanet, GJ 436b, passes in front.” An exoplanet is a planet outside our solar system, and a red dwarf star is a small, relatively cool, low-burning star. “The cloud forms a comet-like tail as a result of ultraviolet light coming from the star pushing on the hydrogen and causing it to spiral outwards,” Wheatley continued. He added that the amount of gas being lost is about 1,000 metric tons per second, equivalent to about one-thousandths of the weight of the planet every billion years. But “the same process is likely to be much stronger on other exoplanets, where the entire atmosphere could be removed or evaporated to destruction.”