mm VLBA Observations of SiO masers: probing the close stellar environment of the PPN OH231.8+4.2

Desmurs, J. F.; Contreras, C. Sanchez; Bujarrabal, V.; Alcolea, J.; Colomer, F.

mm VLBA Observations of SiO masers: probing the close stellar environment of the PPN OH231.8+4.2

Authors

Desmurs, J. F.

Contreras, C. Sanchez

Bujarrabal, V.

Alcolea, J.

Colomer, F.

Description

We present milliarsecond-resolution maps of the SiO maser emission v=1 J=2-1 (3 mm) in the bipolar post-AGB nebula OH231.8+4.2, and compare them with our previous observations of the v=2 J=1-0 line (7 mm). Our observations show that the SiO masers arise in several bright spots forming a structure elongated in a direction perpendicular to the symmetry axis of the nebula. This, and the complex velocity gradient observed, is consistent with the presence of an equatorial torus in rotation and with an infall of material towards the star.
2 pages. 1 figure. Proceedings of the 7th European VLBI Network Symposium held in Toledo, Spain on October 12-15, 2004. Editors: R. Bachiller, F. Colomer, J.-F. Desmurs, P. de Vicente (Observatorio Astronomico Nacional), p. 213-214. Needs evn2004.cls