Spitzer observations of Bow Shocks and Outflows in RCW 38

TL;DR

This study uses Spitzer and Chandra observations to identify bow shocks, outflows, and young stellar objects in RCW 38, revealing ongoing star formation and feedback processes in this massive star-forming region.

Contribution

First detailed infrared and X-ray analysis of bow shocks and outflows in RCW 38, linking feedback to star formation activity and identifying new YSOs and jets.

Findings

Detection of five bow shocks in RCW 38, with one only visible at 24 microns.

Identification of a jet and candidate HH objects in the nearby cluster DBS2003-124.

Evidence that outflows and feedback influence ongoing star formation in the region.

Abstract

We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at IRAC wavelengths, the fifth is visible only at 24 microns. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS~2, have caused an outflow to the NE and SW of the central subcluster. The southern lobe of hot ionised gas is detected in X-rays; shocked gas and heated dust from the shock-front are detected with Spitzer at 4.5 and 24 microns. The northern outflow may have initiated the present generation of star formation, based on the filamentary distribution of the protostars in the central subcluster. Further, the bow-shock driving star, YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are identified within this pillar at near- to mid-IR wavelengths. We also report on IRAC 3.6 & 5.8 micron observations of the cluster DBS2003-124, NE of RCW 38, where 33 candidate YSOs are identified. One star associated with the cluster drives a parsec-scale jet. Two candidate HH objects associated with the jet are visible at IRAC and MIPS wavelengths. The jet extends over a distance of ~3 pc. Assuming a velocity of 100 km/s for the jet material gives an age of about 30,000 years, indicating that the star (and cluster) are likely to be very young, with a similar or possibly younger age than RCW 38, and that star formation is ongoing in the extended RCW 38 region.