AAS 201st Meeting, January, 2003
Session 66. Star Formation II
Oral, Tuesday, January 7, 2003, 2:00-3:30pm, 608-609

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[66.02U] Variability of SiO Masers at 43 GHz in the Bipolar Nebula IRAS 19312+1950

K. Scott (Univ. of Evansville and Maria Mitchell Obs.)

SiO masers at several transitions had been detected in the bipolar nebula IRAS 19312+1950 by Nakashima and Deguchi in May 2000. While other SiO transitions showed only one velocity component at approx. 25 km/s, the J=1-0, v=2 transition demonstrated another component at approx. 53 km/s. We observed the source in June 2002 in the J=1-0, v=1 and v=2 transitions at 43 GHz with the Haystack 37m telescope. The 53 km/s feature was detected in both transitions, but no feature was seen at 25 km/s. We conclude that there are in this source two centers of strongly variable maser activity, widely separated in radial velocity (approx. 28 km/s). This resembles the unique, double-peaked SiO spectrum of Ori-KL, and we hypothesize that IRAS 19312+1950 may be another case of a young object whose SiO maser peaks arise in the receding and approaching sides of a rotating circumstellar disk. This project was supported by the NSF/REU grant AST-0097694 and the Nantucket Maria Mitchell Association.

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.