Issue |
A&A
Volume 694, February 2025
|
|
---|---|---|
Article Number | A199 | |
Number of page(s) | 20 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202348883 | |
Published online | 13 February 2025 |
Multi-scale analysis of the Monoceros OB 1 star-forming region
III. Tracing the dense gas in the massive clump G202.3+2.5
1
Eötvös Loránd University, Department of Astronomy,
Pázmány Péter sétány 1/A,
1117
Budapest,
Hungary
2
Institut UTINAM, CNRS UMR 6213, OSU THETA, Université de Franche-Comté,
41 bis avenue de l’Observatoire,
25000
Besançon,
France
3
IRAP, Université de Toulouse, CNRS, CNES, UPS,
9 av. du Colonel Roche, BP 44346,
31028
Toulouse,
France
4
Department of Physics,
PO Box 64,
00014 University of Helsinki,
Finland
5
University of Debrecen, Faculty of Science and Technology,
Egyetem tér 1,
4032
Debrecen,
Hungary
★ Corresponding author; julien.montillaud@univ-fcomte.fr
Received:
7
December
2023
Accepted:
3
December
2024
Context. Young massive clumps are relatively rare objects and are typically found at large distances. The G202.02+2.85 (hereafter, G202) massive clump was identified in the Monoceros OB 1 molecular complex at a distance of about 700 pc. It was found to be undergoing active star formation and located at the junction point between two colliding filaments.
Aims. We aim to further clarify the evolutionary stage of the clump and the nature of the collision and of six dense cores in the area; specifically, we investigate whether the clump is collapsing as a whole and/or whether it shows signs of shocks.
Methods. To this end, we examined the dense gas properties, notably through NH3 and N2H+ and their deuterated counterparts. We examined the evolutionary stages of the cores through deuterium fractionation values. We performed a mapping of the clump and deeper pointed molecular line observations towards the dense cores with the IRAM 30-m and Effelsberg 100-m telescopes in the 3-mm and centimetre ranges, respectively. The clump internal dynamics was examined using tracers of various gas densities (CO isotopologues, CS, ammonia, and diazenylium), along with a classical infall diagnosis with HCO+ and diazenylium. Furthermore, SiO and methanol were used to characterise the shock properties. The evolutionary stages of the dense cores were evaluated from the deuterium fractionation of ammonia and diazenylium.
Results. The clump seen in dust continuum emission was detected in all dense-gas molecular tracers, including deuterated ammonia and diazenylium, contrasting with the distributions in shock tracers SiO and CH3OH. These latter include both features compatible with protostellar outflows and a more diffuse emission in the clump, all with SiO line width corresponding to relatively low velocity shocks (≲10 km s−1). This could arise from multiple, blended outflows or be a signature of the filament collision. All the dense cores, except for the source 1446, were found to be in early evolutionary stages, the most massive one, the source 1450, being at most a Class 0 object. This is consistent with the idea that they originate in the same clump-compression event. They all present virial parameters indicating gravitational instability, while source 1450 and its surroundings show blue-shift asymmetry in HCO+ compatible with gravitational infall, suggesting that this star formation activity came out of the collision. We find that, in contrast to NH3 deuterium fractionation, the N2H+ deuterium fractionation values are likely to be correlated with the source evolutionary stage.
Conclusions. Our results provide additional evidence that the star-forming cores in the G202 clump originate in the clump compression due to filament collision or convergence. Based on its physical parameters, we find that the source 1454 in the northern clump of G202 may represent the physical state of the region before the collision of the two filaments that make up the junction region. Determining the origin of the collision will require the examination of the large-scale motion of the gas.
Key words: stars: formation / stars: protostars / ISM: clouds / ISM: molecules
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.