ChinaFocus:Researchersclassifyatmosphericescapemechanismoflow-massexoplanets_GuangmingOnlineKUNMING,May9(Xinhua)--AgroupofChineseresearchershasofferedaperspectiveontheatmosphericescapeprocessesoflow-massexoplanets,specificallyaprocessknownashydrodynamicescape,accordingtoaresearcharticlepublishedinthejournalNatureAstronomyonThursday.Thisresearchrevealedvariousdrivingmechanismsaffectingthehydrodynamicescapesandproposedanewclassificationmethodtounderstandtheescapeprocesses.Exoplanetsrefertoplanetsoutsidethesolarsystemandareapopularsubjectinastronomicalresearch.Theatmospheresoftheseplanetscanleavetheplanetandenterspaceforvariousreasons.Onesuchreasonishydrodynamicescape,whichistheprocessoftheupperatmosphereleavingtheplanetasawhole.AccordingtotheresearchersfromtheChineseAcademyofSciencesYunnanObservatories,thisprocessismuchmoreintensethantheparticlebehaviorescapeobservedinthesolarsystem'splanets.Theyaddedthathydrodynamicatmosphericescapemighthavehappenedintheearlystagesofthesolarsystem'splanets."IfEarthhadlostitsentireatmosphereviahydrodynamicescapeatthattime,itmighthavebecomeasdesolateasMars,"explainedGuoJianheng,aresearcherwiththeYunnanObservatories.EventhoughthisintenseescapenolongeroccursonplanetslikeEarth,spaceandgroundtelescopeshaveobservedthathydrodynamicescapestilloccursonsomeexoplanetsthatareveryclosetotheirhoststars.Thisprocessnotonlychangestheplanet'smassbutalsoaffectsitsclimateandhabitability.Beforethisstudy,peoplereliedoncomplexmodelstodeterminewhichphysicalmechanismwasdrivingthehydrodynamicescapeonaplanet,andtheconclusionswereoftenobscure.Theresearchersfoundthatthehydrodynamicatmosphericescapeoflow-massexoplanetscouldbedriveneithersolelyorjointlybytheplanet'sinternalenergy,theworkdonebythestar'stidalforces,orheatingbythestar'sextremeultravioletradiation.Theyproposedthatjustusingthebasicphysicalparametersofthestarandplanet,suchasmass,radius,andorbitaldistance,canclassifythemechanismsofhydrodynamicescapefromlow-massplanets.Onplanetswithlowmassandlargeradius,sufficientinternalenergyorhightemperaturecandriveatmosphericescape.Thestudyfoundthattheplanet'sinternalandpotentialenergyratiocandeterminewhethertheaforementionedescapeoccurs.Forplanetswhoseinternalenergycannotdriveatmosphericescape,researcherscanaccuratelydistinguishtherolesofstellartidalforcesandextremeultravioletradiationbyintroducingtidalforcesfromstarstocorrecttheratioofinternalenergytopotentialenergy.Theresultsofthisstudyarehelpfulinunderstandinghowaplanet'satmosphereevolvesovertimebutalsohavepotentialapplicationsinexploringtheevolutionandoriginsoflow-massplanets.Editor:DisclaimerTheviewsandopinionsexpressedinthisarticlearethoseoftheauthor's,GMW.cnmakesnorepresentationsastoaccuracy,suitability,orvalidityofanyinformationonthissiteandwillnotbeliableforanyerrors,omissions,ordelaysinthisinformation.