The JCMT Gould Belt Survey : evidence for dust grain evolution in Perseus star-forming clumps

The dust emissivity spectral index, β, is a critical parameter for deriving the mass and temperature of star-forming structures, and consequently their gravitational stability. The β value is dependent on various dust grain properties, such as size, porosity, and surface composition, and is expected to vary as dust grains evolve. Here we present β, dust temperature, and optical depth maps of the star-forming clumps in the Perseus Molecular Cloud determined from fitting SEDs to combined Herschel and JCMT observations in the 160 μm, 250 μm, 350 μm, 500 μm, and 850 μm bands. Most of the derived β, and dust temperature values fall within the ranges of 1.0 - 2.7 and 8 - 20 K, respectively. In Perseus, we find the β distribution differs significantly from clump to clump, indicative of grain growth. Furthermore, we also see significant, localized β variations within individual clumps and find low β regions correlate with local temperature peaks, hinting at the possible origins of low β grains. Throughout Perseus, we also see indications of heating from B stars and embedded protostars, as well evidence of outflows shaping the local landscape.