WeeklyScienceUpdateFriday,June29,2012SmallExoplanetsMayAboundNotallstarsarecreatedequal.Althoughallofthemarebornmostlywithhydrogen,thetraceamountsofotherelementspresentcanvarybyatleastafactoroften,dependingontheparticularconditionsofthestar'sbirthcloud.Sinceplanetscondenseoutofthematerialindisksaroundyoungstars,astronomerswonderwhetherstarswithrelativelylargeamountsoftheseotherelementswillmakerockyplanetsmoreeasily.Spectralobservationsofthestar'slightcanrevealitsoriginalelementalcomposition,whilethedramaticnewmethodsfordetectingexoplanetscanidentify,atleastapproximately,whichstarshostrockyplanets(liketheEarth)andwhichoneshostprimarilygaseousplanets(likeJupiter).Recentobservationshaveconcludedthatheavy-element-richstarsaremuchmorelikelytoharborgasgiantplanetslikeJupiter,buttherelationshipforthesmaller,Earth-sizedplanetshasbeenunknown.Inthelatestissueofthejournal,Nature,CfAastronomersDaveLatham,GuillermoTorres,GilbertEsquerdo,JohnGeary,BobStefanik,andSamuelQuinn,andtheircolleaguesreportontheirspectroscopicstudiesof152starshostingexoplanets,asubsetofthe1235candidatestarsidentifiedbytheKeplersatelliteashoststars.ThescientistsfindthatplanetswithradiilessthanfourEarthradiiformaroundhoststarswithawiderangeofelementalabundances(butonaverage,theylookliketheSun),whereaslargeplanetslikeJupiterpreferentiallyformaroundstarsthathaveahigherabundancesofelementsthandoestheSun.ThewidevarietyofconditionsinstarsthathostEarth-likeplanetspromptstheteamtoconcludethatterrestrialplanetsmaybewidespreadinthediskoftheGalaxy,withnospecialrequirementofenhancedelementabundancesneededfortheirformation.HYPERLINK"http://www.cfa.harvard.edu/news/2012/su201226.html"SmallExoplanetsMayAboundThisartist'sillustrationshowsthe63hotJupitersystems(planetarysystemswithJupiter-sizeplanetcandidates)inthree-dayorbits,withsimulatedstellarcolors,anddisksandtransitingplanetsilhouettesshownatthesamerelativescale.Credit:FermilabCenterforParticleAstrophysics/JSteffenHYPERLINK"http://www.cfa.harvard.edu/image