The JCMT Gould Belt Survey: First results from the Corona Australis molecular cloud and evidence of variable dust emissivity indices in the Coronet region

Pattle, K., Bresnahan, D., Ward-Thompson, D. ORCID: https://orcid.org/0000-0003-1140-2761, Kirk, H., Kirk, J.M., Berry, D.S., Broekhoven-Fiene, H., Hatchell, J., Jenness, T., Johnstone, D., Mottram, J.C., Duarte-Cabral, A. ORCID: https://orcid.org/0000-0002-5259-4774, Francesco, J.Di, Hogerheijde, M.R., Bastien, P., Butner, H., Chen, M., Chrysostomou, A., Coudé, S., Currie, M.J., Davis, C.J., Drabek-Maunder, E., Fich, M., Fiege, J., Friberg, P., Friesen, R., Fuller, G.A., Graves, S., Greaves, J. ORCID: https://orcid.org/0000-0002-3133-413X, Holland, W., Joncas, G., Knee, L.B.G., Mairs, S., Marsh, K. ORCID: https://orcid.org/0000-0003-0107-7803, Matthews, B.C., Moriarty-Schieven, G., Mowat, C., Rawlings, J., Retter, B., Richer, J., Robertson, D., Rosolowsky, E., Sadavoy, S., Thomas, H., Tothill, N., Viti, S., White, G.J., Wouterloot, J., Yates, J. and Zhu, M. 2025. The JCMT Gould Belt Survey: First results from the Corona Australis molecular cloud and evidence of variable dust emissivity indices in the Coronet region. Monthly Notices of the Royal Astronomical Society 10.1093/mnras/staf009

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Abstract

We present 450 $\mu$m and 850 $\mu$m James Clerk Maxwell Telescope (JCMT) observations of the Corona Australis (CrA) molecular cloud taken as part of the JCMT Gould Belt Legacy Survey (GBLS). We present a catalogue of 39 starless and protostellar sources, for which we determine source temperatures and masses using SCUBA-2 450 $\mu$m/850 $\mu$m flux density ratios for sources with reliable 450 $\mu$m detections, and compare these to values determined using temperatures measured by the Herschel Gould Belt Survey (HGBS). In keeping with previous studies, we find that SCUBA-2 preferentially detects high-volume-density starless cores, which are most likely to be prestellar (gravitationally bound). We do not observe any anti-correlation between temperature and volume density in the starless cores in our sample. Finally, we combine our SCUBA-2 and Herschel data to perform SED fitting from 160–850 $\mu$m across the central Coronet region, thereby measuring dust temperature T, dust emissivity index β and column density N(H2) across the Coronet. We find that β varies across the Coronet, particularly measuring β = 1.55 ± 0.35 in the colder starless SMM-6 clump to the north of the B star R CrA. This relatively low value of β is suggestive of the presence of large dust grains in SMM-6, even when considering the effects of T − β fitting degeneracy and 12CO contamination of SCUBA-2 850 $\mu$m data on the measured β values.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-01-07
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	20 January 2025
Last Modified:	20 Jan 2025 14:30
URI:	https://orca.cardiff.ac.uk/id/eprint/175409

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