科普英语:星系为何停止形成恒星

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2018-10-09

Galaxiescomeinthreemainshapes-elliptical,spiral(suchastheMilkyWay),,,thatis,ceasestarformation,arenotwellunderstood,however,andc,usingalargesampleofaround70,000galaxies,ateamofresearchersledbyUniversityofCalifornia,RiversideastronomersBehnamDarvishandBa,whichincludedscientistsattheCaliforniaInstituteofTechnologyandLancasterUniversity,UnitedKingdom,combedthroughavailabledatafromtheCOSMOSUltraVISTAsurveythatgiveaccuratedistanceestimatesforgalaxiesoverthepast11billionyears,andfocusedontheeffectsofexternala,theresearchteamnotes,includedraggeneratedfromaninfallinggalaxywithinaclusterofgalaxies,whichpullsgasaway;multiplegravitationalencounterswithothergalaxiesandthedensesurroundingenvironment,resultinginmaterialbeingstrippedawayfromthegalaxy;andthehaltingofthesupplyofcoldgastothegalaxy,thusstranglingthegalaxablackhole(inwhichjets,winds,orintenseradiationheatuphydrogengasinthegalaxyorblowitoutcompletely,thuspreventingthegasfromcoolingandcontractingtoformstars)andstellaroutflow(forexample,high-velocitywindsproducedbymassiveyoungstarsandsupernovaethatpushthegasoutofthehostgalaxy).Byusingtheobservablepropertiesofthegalaxiesandsophisticatedstatisticalmethods,weshowthat,onaverage,externalprocessesareonlyrelevanttoquenchinggalaxiesduringthelasteightbillionyears,saidDarvish,aformergraduatestudentintheUCRiversideDepartmentofPhysicsandAstronomyandthefirstau,internalprocessesarethedominantmechanismforshuttingoffstar-formationbeforethistime,andclosertothebeginningoftheuniverse.本文链接:http:///xuexi/yingyu/201711/本站内容如无特别说明,均来自网络和网友投稿!如侵犯了您的权利,请联系我们删除。