Bow shocks around runaway stars

We found nine new stellar bow shock candidates, three new bubble candidates, and one intermediate structure candidate. One of them is an in situ bow shock candidate. We also found 17 already known bow shocks in our sample, though we discarded one, and 62 miscellaneous sources showing some IR emission around the runaways.

We geometrically characterized the sources in IR using the WISE-4 band and estimated the ISM density at the bow shock positions, obtaining median values of ~6 and ~4cm^-3^ using 2D and 3D peculiar velocities, respectively. Most of the new discovered bow shocks come from new runaway discoveries. Within our samples we found that ~24% of the O-type runaway stars show bow shocks, while this decreases to ~3% for Be-type runaway stars.

Two bow shocks present radio emission but not as clear counterparts, and two others show hints of radio emission. The physical scenarios indicate that two sources could still be compatible with nonthermal radio emission. The new sample of O and Be runaway stars allowed us to discover both new stellar bow shocks and bubbles.

Their geometrical characterization can be used to assess the physical scenario of the radio emission. Deeper radio observations are needed to unveil a population of radio-detected bow shocks, and the physical scenarios occurring in these sources.