Astrometry of Galactic Star-Forming Region Sharpless 269 with VERA: Parallax Measurements and Constraint on Outer Rotation Curve
[摘要] Wehaveperformedhigh-precisionastrometryofH$$_2$$OmasersourcesintheGalacticstar-formingregionSharpless269(S269)withVERA.Wesuccessfullydetectedatrigonometricparallaxof$$189pm8mu$$as,correspondingtoasourcedistanceof$$5.28^{+0.24}_{-0.22}$$kpc.Thisisthesmallestparallaxevermeasured,andthefirstonedetectedbeyond5kpc.ThesourcedistanceaswellasthepropermotionswereusedtoconstraintheouterrotationcurveoftheGalaxy,demonstratingthatthedifferenceofrotationvelocitiesattheSunandatS269(whichis13.1kpcawayfromtheGalaxy’scenter)islessthan3%.Thisgivesthestrongestconstraintontheflatnessoftheouterrotationcurve,andprovidesadirectconfirmationoftheexistenceofalargeamountofdarkmatterintheGalaxy’souterdisk.
[发布日期] [发布机构]
[效力级别] [学科分类] 天文学(综合)
[关键词] "ISM: star forming regions";"ISM: individual objects (Sharpless 269)";"masers (H2O)";VERA [时效性]
