Distribution and Kinematics of Molecular Gas in Barred Spiral Galaxies. II. NGC 253

[摘要] Thelargescalemappingofthediskofanearbybarredgalaxy,NGC253inCO(J=1–0),wasmadewithanangularresolutionof16″.Moleculargasconcentratesinthenuclearregionandthelarge-scalebarseeninnear-infraredimages.Theradialdistributionofmoleculargasindicatesasecondarypeak,whoseradiusagreeswiththatoftheHαringandtheendsofthebar,aswellasacentralstrongpeak.Theradialdistributioniswellfittedbyanexponentialfunctionorapowerlawoutsidethesecondarypeak.Arotationcurveisrisingintheinnerregionandchangestoflatatthering.Thesefactssuggestthatmoleculargasinfallsfromtheouterdiskbylosingangularmomentumduetogaseousviscosityintheregionofthedifferentialrotation,andaccumulatesatthering.Inthebarregion(andwithinthecorotationradius),moleculargasagainlosesitsangularmomentumduetothebarpotential,andisinfallingtowardthenuclearregion.Theupperlimitofthenoncircularmotionalongthemajoraxisofthebarintheleadingedgeofthebaris≈70–130kms−1intherestframeofthebar.

[学科分类] 天文学(综合)

[关键词] "galaxies: individual (NGC 253)";"galaxies: kinematics and dynamics";"galaxies: starburst";"galaxies: structure";"ISM: molecules"