Detections of SiO and H2O Masers in the Bipolar Nebula IRAS 19312+1950

[摘要] WereportonthedetectionofSiOandH2Omaserstowardanewlyfoundbipolarnebula,IRAS19312+1950.ThisobjectexhibitsextremeredIRAScolor[log(F25/F12)=0.5andlog(F60/F25)=0.7]andanebulosityhavingasizeofabout30″extendedtothesouth-westinthe2MASSnear-infraredimage.Towardthisobject,wehavedetectedemissionfromtheH2O6(1,6)–5(2,3)transition,theSiOJ=1–0,v=1and2,andJ=2–1,v=1transitions,andtheSO2(2)–1(1)andH13CNJ=1–0transitions.ThethermallinesofSOandH13CNareshiftedbyabout12kms−1inradialvelocitywithrespecttothemaserlines,indicatingthatthermalemissioncomesfromthebackgroundmolecularcloud.However,theSiOJ=2−1,v=2spectrumshowsanothercomponentofSiOemissionseparatedby26kms−1fromthemaincomponent,thatmightbeformedinarotatingorexpandingshell.

[学科分类] 天文学(综合)

[关键词] "ISM: molecules";masers;"planetary nebulae: individual (IRAS 19312+1950)";"stars: AGB and post-AGB";"stars: mass-loss"