Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8 microns, there is a flattened structure seen in absorption against the background emission. The structure is perpendicular to the outflow and is extended to a diameter of 2 arcminutes. This structure is the first clear detection of a flattened circumstellar envelope or pseudo-disk around a Class 0 protostar. Such a flattened morphology is an expected outcome for many collapse theories that include magnetic fields or rotation. We construct an extinction model for a power-law density profile, but we do not constrain the density power-law index.
Cite
@article{arxiv.0710.2314,
title = {A Flattened Protostellar Envelope in Absorption around L1157},
author = {Leslie Looney and John Tobin and Woojin Kwon},
journal= {arXiv preprint arXiv:0710.2314},
year = {2009}
}