A radio continuum and neutral hydrogen counterpart to the IRAS Vela shell

Abstract

Aims. We look for radio-continuum and atomic neutral hydrogen (Hi) counterparts of the IRAS Vela shell (IVS). Methods. Neutral hydrogen (Hi) and 1410 MHz radio continuum surveys carried out with the Instituto Argentino de Radioastronomía (IAR) dishes are the main databases used in this investigation. Results. A good morphological correlation was found between arc-shaped structures at radio wavelengths and in the 100 μm IR emission. This correlation is observed at velocities of the Hi between -17.5 and -2.1 km s<SUP>-1</SUP>, in agreement with the velocities of the molecular gas detected in the region. The radial distribution of the different components is consistent with the presence of an expanding shell that is being ionized from inside. Assuming a distance of 400 pc, the amount of ionized and atomic gas associated with the IVS is 2.3 × 10<SUP>4</SUP> and 6.8 × 10<SUP>4</SUP> solar masses, respectively. The origin of the expansion of the IVS could not be identified.