Jets and Wide Angle Outflows in Cepheus E: New Evidence from Spitzer

TL;DR

This study uses enhanced Spitzer infrared imaging to reveal detailed structures of jets and wide angle outflows in the young protostar Cepheus E, providing new insights into their morphology and shock properties.

Contribution

It introduces a novel image processing approach with HiRes deconvolution to improve resolution and analyze jet/outflow features in Cepheus E in unprecedented detail.

Findings

Detection of wide angle outflow in scattered light

Identification of 29 jet-driven bow shocks and knots

Spectroscopic analysis of shock-heated gas in jets

Abstract

In some protostellar objects both wide angle outflows and collimated jets are seen, while in others only one is observed. Spitzer provides unprecedented sensitivity in the infrared to study both the jet and outflow features. Here, we use HiRes deconvolution to improve the visualization of spatial morphology by enhancing resolution (to sub-arcsecond levels in the IRAC bands) and removing the contaminating sidelobes from bright sources. We apply this approach to study the jet and outflow features in Cep E a young, energetic Class 0 protostar. In the reprocessed images we detect: (i) wide angle outflow seen in scattered light; (ii) morphological details on at least 29 jet driven bow shocks and jet heads or knots; (iii) three compact features in 24 micron continuum image as atomic/ionic line emission coincident with the jet heads; and, (iv) a flattened 35 arcsec size protostellar envelope seen against the interstellar background PAH emission as an absorption band across the protostar at 8 micron. By separating the protostellar photospheric scattered emission in the wide angle cavity from the jet emission we show that we can study directly the scattered light spectrum. We present the H2 emission line spectra, as observed in all IRAC bands, for 29 knots in the jets and bowshocks and use them in the IRAC color -- color space as a diagnostic of the thermal gas in the shocks driven by the jets. The data presented here will enable detailed modeling of the individual shocks retracing the history of the episodic jet activity and the associated accretion on to the protostar. The Spitzer data analysis presented here shows the richness of its archive as a resource to study the jet/outflow features in H2 and scattered light in a large homogeneous sample.