Characterization of dense Planck clumps observed with Herschel and SCUBA-2^⋆,⋆⋆

¹ Department of Physics, PO box 64, 00014 University of Helsinki, Finland
e-mail: emma.mannfors@helsinki.fi
² Astronomy Department, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago de Chile, Chile
³ Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
⁴ Yunnan Observatories, Chinese Academy of Sciences, Phoenix Mountain, East Suburb of Kunming, 650216 Yunnan, PR China
⁵ Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing 100101, PR China
⁶ Nobeyama Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan
⁷ Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejon 34055, Republic of Korea
⁸ University of Science & Technology, 176 Gajeong-dong, Yuseong-gu, Daejeon, Republic of Korea
⁹ Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China
¹⁰ Institut UTINAM – UMR 6213 – CNRS – Univ. Bourgogne Franche Comté, OSU THETA, 41bis avenue de l’Observatoire, 25000 Besançon, France
¹¹ East Asian Observatory, 660 N. A’ohōkū Place, University Park, Hilo, HI 96720, USA
¹² National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹³ Department of Astronomical Science, The Graduate University for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁴ Institute of Astronomy and Astrophysics, Academia Sinica. 11F of Astronomy-Mathematics Building, AS/NTU No.1, Section 4, Roosevelt Rd, Taipei 10617, Taiwan
¹⁵ SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, Moffett Field, CA 94035, USA
¹⁶ IAPS-INAF, via Fosso del Cavaliere 100, 00133 Rome, Italy

Received: 21 February 2020
Accepted: 23 May 2021

Abstract

Context. Although the basic processes of star formation (SF) are known, more research is needed on SF across multiple scales and environments. The Planck all-sky survey provided a large catalog of Galactic cold clouds and clumps that have been the target of several follow-up surveys.

Aims. We aim to characterize a diverse selection of dense, potentially star-forming cores, clumps, and clouds within the Milky Way in terms of their dust emission and SF activity.

Methods. We studied 53 fields that have been observed in the JCMT SCUBA-2 continuum survey SCOPE and have been mapped with Herschel. We estimated dust properties by fitting Herschel observations with modified blackbody functions, studied the relationship between dust temperature and dust opacity spectral index β, and estimated column densities. We extracted clumps from the SCUBA-2 850 μm maps with the FellWalker algorithm and examined their masses and sizes. Clumps are associated with young stellar objects found in several catalogs. We estimated the gravitational stability of the clumps with virial analysis. The clumps are categorized as unbound starless, prestellar, or protostellar.

Results. We find 529 dense clumps, typically with high column densities from (0.3–4.8) × 10²² cm⁻², with a mean of (1.5 ± 0.04) ×10²² cm⁻², low temperatures (T ∼ 10–20 K), and estimated submillimeter β = 1.7 ± 0.1. We detect a slight increase in opacity spectral index toward millimeter wavelengths. Masses of the sources range from 0.04 M_⊙ to 4259 M_⊙. Mass, linear size, and temperature are correlated with distance. Furthermore, the estimated gravitational stability is dependent on distance, and more distant clumps appear more virially bound. Finally, we present a catalog of properties of the clumps.

Conclusions. Our sources present a large array of SF regions, from high-latitude, nearby diffuse clouds to large SF complexes near the Galactic center. Analysis of these regions will continue with the addition of molecular line data, which will allow us to study the densest regions of the clumps in more detail.