The extraordinary stellar outflow Ou4

Romano Corradi, Instituto de Astrofisica de Canarias

Ou4 is a recently discovered highly collimated outflow with the impressive size of 1.2 degrees in the sky. It is located inside the 
H ii region Sh 2-129, but its nature is uncertain and its driving source is not yet identified. We present new deep optical images 
and spectra aimed at better understanding the origin of Ou4. The shockexcited nature of gas and its radial velocities strengthen 
the link between Ou4 and the star forming region at the centre of Sh 2-129, and in particular its most massive star, the triple 
system HR 8119 (B0V).