The clos­est ex­o­planet to Earth could be ‘highly hab­it­able’, sci­en­tist claims

Tehran Times - - SCIENCE -

Ever since the dis­cov­ery of the ex­o­planet — known as Prox­ima Cen­tauri b — in 2016, peo­ple have won­dered whether it could be ca­pa­ble of sus­tain­ing life.

Now, us­ing com­puter mod­els sim­i­lar to those used to study cli­mate change on Earth, re­searchers have found that, un­der a wide range of con­di­tions, Prox­ima Cen­tauri b can sus­tain enor­mous ar­eas of liq­uid wa­ter on its sur­face, po­ten­tially rais­ing its prospects for har­bor­ing liv­ing or­gan­isms.

The “ma­jor mes­sage from our sim­u­la­tions is that there’s a de­cent chance that the planet would be hab­it­able,” said Anthony Del Ge­nio, a plan­e­tary sci­en­tist at the NASA God­dard In­sti­tute for Space Stud­ies in New York City. Del Ge­nio is also the lead au­thor of a pa­per de­scrib­ing the new re­search, which was pub­lished Sept. 5 in the jour­nal Astro­bi­ol­ogy.

Red-dwarf star

Prox­ima Cen­tauri is a small, cool red­dwarf star lo­cated just 4.2 light-years from the sun. De­spite its prox­im­ity, sci­en­tists still know very lit­tle about Prox­ima Cen­tauri’s plan­e­tary com­pan­ion, be­sides that its mass is at least 1.3 times that of Earth and that it goes around its par­ent starevery 11 days. There­fore, Del Ge­nio and his col­leagues had to make some rea­son­able guesses about the ex­o­planet Prox­ima Cen­tauri b — namely, that it had an at­mos­phere and an ocean on its sur­face — for their work to pro­ceed.

Prox­ima Cen­tauri b or­bits in its star’s hab­it­able zone, mean­ing it’s at just the right dis­tance to re­ceive enough starlight to keep its sur­face above the freez­ing tem­per­a­ture of wa­ter. But this zone is ex­tremely close to the star, space.com, a Live Sci­ence sis­ter site, re­ported. So it’s likely that the planet has be­come tidally locked due to grav­i­ta­tional forces.

This means that the same side of Prox­ima Cen­tauri b al­ways faces its par­ent star, much like how the moon al­ways shows the same side to Earth.

Pre­vi­ous sim­u­la­tions

Pre­vi­ous sim­u­la­tions pub­lished in a 2016 pa­per in the jour­nal As­tron­omy & Astro­physics mod­eled a hy­po­thet­i­cal at­mos­phere on Prox­ima Cen­tauri b and sug­gested that the star-fac­ing hemi­sphere of the ex­o­planet might be baked un­der an in­tense glare, while a space-fac­ing ocean would be frozen over. There­fore, only a cir­cle of warm sea might ex­ist on Prox­ima Cen­tauri b — a sce­nario Del Ge­nio’s team calls “eye­ball Earth.”

But the new sim­u­la­tions were more com­pre­hen­sive than prior ones; they also in­cluded a dy­namic, cir­cu­lat­ing ocean, which was able to trans­fer heat from one side of the ex­o­planet to the other very ef­fec­tively. In the re­searchers’ find­ings, the move­ment of the at­mos­phere and ocean com­bined so that “even though the night side never sees any starlight, there’s a band of liq­uid wa­ter that’s sus­tained around the equa­to­rial re­gion,” Del Ge­nio told Live Sci­ence.

He likened this heat cir­cu­la­tion to our own planet’s sea­side cli­mates. The U.S. East Coast is balmier than it would be oth­er­wise, he said, be­cause the Gulf Stream car­ries warm wa­ter up from the trop­ics.

The “ma­jor mes­sage from our sim­u­la­tions is that there’s a de­cent chance that the planet would be hab­it­able,” said Anthony Del Ge­nio, a plan­e­tary sci­en­tist at the NASA God­dard In­sti­tute for Space Stud­ies in New York City.

Newspapers in English

Newspapers from Iran

© PressReader. All rights reserved.