Absolute Proper Motions of H2O Masers Away from the Galactic Plane Measured with VERA in the “Superbubble” Region NGC 281

[摘要] Wereportonabsoluteproper-motionmeasurementsofanH2OmasersourceintheNGC281Westmolecularcloud,whichislocated$$sim$$320pcabovetheGalacticplaneandisassociatedwithanHIloopextendingfromtheGalacticplane.Weconductedmulti-epochphase-referencingobservationsofthemasersourcewithVERA(VLBIExplorationofRadioAstrometry)overamonitoringperiodof6months,since2006May.WefindthattheH2OmaserfeaturesinNGC281WestaresystematicallymovingtowardthesouthwestandfurtherawayfromtheGalacticplanewithaverticalvelocityof20–30kms$$^{-1}$$atitsestimateddistanceof2.2–3.5kpc.OurnewresultsprovidethemostdirectevidencethatthegasintheNGC281regionontheHIloopwasblownoutfromtheGalacticplane,mostlikelyinasuperbubbledrivenbymultipleorsequentialsupernovaexplosionsintheGalacticplane.

[学科分类] 天文学(综合)

[关键词] "Galaxy: kinematics and dynamics";"ISM: bubbles";"H II regions";"ISM: individual objects (NGC 281)";"masers (H²O)"