VERA Observations of H$_2$O Maser Sources in Three Massive Star-Forming Regions and Galactic Rotation Measurements

摘要

WepresenttheresultsofVLBIobservationsofthreeH$$_2$$Omasersourcesinmassivestar-formingregions:IRAS06058$$+$$2138,IRAS19213$$+$$1723,andAFGL2789.Wedeterminedtheannualparallaxesandpropermotionsforthesesourcesbyaphase-referencingmethod.TheestimateddistancestoIRAS06058$$+$$2138andAFGL2789are1.76$$pm$$0.11kpcand3.07$$pm$$0.30kpc,whicharelocatedinthePerseusspiralarm.ThedistancetoIRAS19213$$+$$1723is3.98$$pm$$0.57kpc,placingitintheCarinaa€“Sagittariusarm.Withestimated3-dimensionalvelocitycomponents,wehaveshownthatthegalacticrotationcurveisflatintherangeof6.4kpc$$leRle$$13kpcascombiningwithS269,whichwasobservedwithVERA.WehavealsofoundthattheoverallrotationcurveoftheGalaxydonotdependon$$Theta_0$$.Themasersourcesalsoshowdeviationsfromflatrotationcurvesbyafewkilometerspersecond.Wediscusspossiblereasonsforthesepeculiarmotions.