PPMAP and the Gould Belt

Column density map of L1495 produced by PPMAP.

The Taurus L1495 molecular cloud is a nearby (140 pc) filamentary molecular cloud located within the Gould Belt. As an active star forming region with such a well defined structure, it is of great interest as it allows us to observe many of the processes associated with resolved star formation in great detail.

PPMAP is a point process algorithm developed by Cardiff's Dr. Ken Marsh, that allows for unparalleled analysis of dusty regions. It's ability to calculate column density without having to degrade the native resolution of short wavelength images allow for a much more detailed look at the structures that make up regions of interest. In addition, it is able to break down dust into a number of line-of-sight temperature and opacity bins, leading to a much deeper view of extended structure in the ISM. It has even been employed to locate potential star formation in the Brick, a region previously thought to be quiescent.

We impose an 18 arcsecond resolution for the analysis of L1495, to better compare with traditional techniques. Our findings have been published in Howard, et al., 2019. Our main findings are that L1495 is much narrower than previously reported, with a lower line density. This places the filament in a trans-critical regime, with only localised regions forming pre-stellar cores. In addition, we find evidence that the dust contained within the filament is of a different physical form than that of the surrounding cloud.

We now turn our attention to the Ophiuchus molecular cloud, a similar distance (140 pc) from the earth, but boasting a vastly different star forming environment. While L1495 is greatly extended, and a centre of low mass star formation, Ophiuchus is more compact, with some protostars that are much more massive.