Letter to the Editor

Multi-scale analysis of the Monoceros OB 1 star-forming region

I. The dense core population

¹ Institut UTINAM – UMR 6213 – CNRS – Univ. Bourgogne Franche Comté, OSU THETA, 41bis avenue de l’Observatoire, 25000 Besançon, France
e-mail: julien@obs-besancon.fr
² Department of Physics, University of Helsinki, PO Box 64 00014 Helsinki, Finland
³ IRAP, Université de Toulouse, CNRS, UPS, CNES, 31400 Toulouse, France
⁴ Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216, PR China
⁵ Chinese Academy of Sciences, South America Center for Astrophysics (CASSACA), Camino El Observatorio 1515, Las Condes, Santiago, Chile
⁶ Departamento de Astronomía, Universidad de Chile, Las Condes, Santiago, Chile
⁷ Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China
⁸ Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong-gu, Daejeon 34055, Republic of Korea
⁹ East Asian Observatory, 660 N. A’ohoku Place, Hilo, HI 96720, USA
¹⁰ Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
¹¹ University of Science & Technology, 176 Gajeong-dong, Yuseong-gu, Daejeon, Republic of Korea
¹² Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan
¹³ National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁴ SOFIA Science Centre, USRA, NASA Ames Research Centre, MS N232-12, Moffett Field, CA 94035, USA
¹⁵ Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
¹⁶ Department of Physics, School of Science and Humanities, Kabanbay Batyr Ave, 53, Nur-Sultan 010000, Kazakhstan
¹⁷ Eötvös Loránd University, Department of Astronomy, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
¹⁸ Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
¹⁹ Institute of Physics I, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
²⁰ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
²¹ ICC, University of Barcelona, Marti i Franquès 1, 08028 Barcelona, Spain
²² Konkoly Observatory of the Hungarian Academy of Sciences, Konkoly Thege Miklósút 15-17, 1121 Budapest, Hungary
²³ IAPS-INAF, Via Fosso del Cavaliere 100, 00133 Rome, Italy
²⁴ Kavli Institute for Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871, PR China
²⁵ European Southern Observatory (ESO) Headquarters, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

Received: 25 July 2019
Accepted: 9 September 2019

Abstract

Context. Current theories and models attempt to explain star formation globally, from core scales to giant molecular cloud scales. A multi-scale observational characterisation of an entire molecular complex is necessary to constrain them. We investigate star formation in G202.3+2.5, a ∼10 × 3 pc sub-region of the Monoceros OB1 cloud with a complex morphology that harbours interconnected filamentary structures.

Aims. We aim to connect the evolution of cores and filaments in G202.3+2.5 with the global evolution of the cloud and to identify the engines of the cloud dynamics.

Methods. In this first paper, the star formation activity is evaluated by surveying the distributions of dense cores and protostars and their evolutionary state, as characterised using both infrared observations from the Herschel and WISE telescopes and molecular line observations with the IRAM 30 m telescope.

Results. We find ongoing star formation in the whole cloud, with a local peak in star formation activity around the centre of G202.3+2.5, where a chain of massive cores (10 − 50 M_⊙) forms a massive ridge (≳150 M_⊙). All evolutionary stages from starless cores to Class II protostars are found in G202.3+2.5, including a possibly starless and massive (52 M_⊙) core, which presents a high column density (8 × 10²² cm⁻²).

Conclusions. All the core-scale observables we examined point to an enhanced star formation activity that is centred on the junction between the three main branches of the ramified structure of G202.3+2.5. This suggests that the increased star formation activity results from the convergence of these branches. To further investigate the origin of this enhancement, it is now necessary to extend the analysis to larger scales in order to examine the relationship between cores, filaments, and their environment. We address these points through the analysis of the dynamics of G202.3+2.5 in a joint paper.