Multifrequency study of the ring nebula SG 13

J.Vasquez(1,2), C.E.Cappa(1,2), and S. Pineault(1,3)

1 - Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET), C.C.5, 1894, Villa Elisa, Argentina;
2 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, La Plata, Argentina;
3 - Départment du physique, de génie physique et d'optique and Centre de
recherche en astrophysique du Québec (CRAQ), Université Laval, Québec, Canada GIVOA6

We investigate the morphology and kinematics of the interstellar medium in the
environs of the open cluster Mrk 50, which includes the Wolf-Rayet star WR 157
and a number of early B-type stars. The analysis was performed using radio con
tinuum images at 408 and 1420 MHz, and HI 21cm line data taken from the Canadian Galactic Plane Survey, molecular observations of the CO(1-0) line at 115 GHz from the Five College Radio Astronomy Observatory and available mid and far IR observations obtained with the MSX and IRAS satellites, respectively.

This study allowed identification of the radio continuum and molecular counterpart of the ring nebula SG 13, while no neutral atomic structure was found to be associated. The nebula is also detected in images in the mid and far infrared, showing the existence of dust well mixed with the ionized gas. We estimate the main physical parameters of the material linked to the nebula.

The interstellar gas distribution in the environs of Mrk 50 is compatible with
a stellar wind bubble created by the mass loss from WR 157.

The distribution of young stellar object (YSO) candidates in the region shows that stellar formation activity may be present in the molecular shell that encircles the ring nebula.

Reference: MNRAS
Status: Manuscript has been accepted