Near-Infrared Observations of the IRAS/SiO Sources in the Galactic Bulge: a Large Scale Distribution

摘要

Near-infraredphotometricobservationsinthe$$J$$-,$$H$$-,and$$K$$-bandsweremadefor120IRASsourcestowardtheGalacticbulge($$-10^{circ}l15^{circ}$$and$$vertbvert3^{circ}$$,excluding$$vertlvert3^{circ}$$).Theyarewell-confirmed,mass-losinglate-typestarshavingaccurateradialvelocitiesderivedfromSiOmaserobservations.For118sources,single,unambiguousnear-infraredcounterpartswerefoundwithintheerrorsoftheIRAS/MSXpositions;andfortheother2sources,faintcandidatesonlydetectableinthe$$K$$-bandwerefound.Fromthe$$J$$-,$$H$$-,$$K$$-bandandIRAS12and25$$,{mumathrm{m}}$$intensities,weestimatedthespectralenergydistributionsofthesources,andobtaineddistancesassumingaconstantintrinsicluminosity.AddingallofthedistancedataoftheIRAS/SiOsourcesin$$-10^{circ}l25^{circ}$$publishedinpreviouspapers,wemappedthepositionsof272sampledstarsontotheGalacticplane.Themapclearlyshowsabarstructure,wherethemajoraxisofthebarisoriented$$22^{circ}(pm8^{circ}$$)fromtheSun-Galacticcenterline.Wealsoreanalyzedtheradial-velocityshiftwiththedistanceinthissample.TheseanalysessuggestthatthedataareconsistentwiththecurrentbartheoryoftheGalacticbulge.