First NIR Polarimetry of 30 Doradus

[摘要] Wehavecarriedoutthefirstnear-infrared(NIR)polarimetricimagingobservationsofthecentralpart(7$$lap{.}^{prime}$$7$$imes$$7$$lap{.}^{prime}$$7$$sim110{m;pc}imes110{m;pc}$$)of30Doradus.Thetotalsof106,131,and34sourceshavesignificantpolarizationdegreesat$$J,H$$,and$$K_{ms}$$,respectively.The$$E$$-vectorstoward30Dorweremappedwithunprecedentedlyhighresolutions.Aspreviouslynoticedbyopticalobservations,thereisanoveralltendencyforthe$$E$$-vectorstoberoughlyalignedintheeast-westdirection.Inaddition,ourobservationsrevealamorecomplexstructureoftheiralignment.Thepositionanglesofthe$$E$$-vectorsarenotuniform,butshowagradualspatialvariation.Itisplausibletoassumethattheytracethemagneticfieldtoward30Dor.Oneoftheexpandingshellstoward30Dor,Shell5,isclearlyenvelopedby$$E$$-vectors.Theexpandingshellhasprobablysweptthemagneticfieldtogetherintotherim,whilecreatingthecurvedstructure.WeobtainedtheratiosofpolarizationdegreeamongtheNIRwavelengths:$$P_H/P_J=0.76pm0.02$$and$$P_{K_{ms}}/P_H=0.87pm0.06$$.Thesefitapower-lawdependenceof$$Pproptolambda^{-0.9}$$.

[学科分类] 天文学(综合)

[关键词] "Magellanic Clouds";"infrared: ISM";"ISM: magnetic fields";polarization