Far-Infrared Distributions in Nearby Spiral Galaxies NGC 2841 and NGC 2976 Observed with AKARI/Far-Infrared Surveyor (FIS)

摘要

Far-infrared(IR)imagesofthenearbySbgalaxyNGC2841andtheScgalaxyNGC2976atwavelengthsof65,90,140,and160$$mu$$mhavebeenobtainedwiththeFar-InfraredSurveyor(FIS)onboardAKARI.Bothgalaxiesrevealsimilarmorphologiesofdustrings.Theyare,however,significantlydifferentinthedusttemperature:acold($$sim$$21K)ringforNGC2841andawarm($$sim$$30K)ringforNGC2976,whichpresumablyreflectsthedifferenceintheoriginoftheringstructureforthedifferentHubbletypesofthegalaxy.Inadditiontothedust-ringstructure,awarmdustcomponentwasdetectedfromthecentralregionofNGC2841,whichmaybeattributedtoheatingbyitsLow-IonizationNuclearEmission-lineRegionnucleus.AsforNGC2976,anextendeddustcomponentwasobservedalongtheminoraxis,whichshowsadistributionsomewhatasymmetricaltothegalacticdisk;thismightbeassociatedwiththeHIbridgeintheM81/M82groupthatNGC2976belongsto.Bytakingadvantageofawealthofthefar-IRbandsoftheFIS,ithasbeendemonstratedthatthespectralenergydistributionofNGC2841isspatiallymorevariablethanthatofNGC2976.