Dynamics of cluster-forming hub-filament systems. The case of the high-mass star-forming complex Monoceros R2

DOI: 
10.1051/0004-6361/201935260
Publication date: 
01/09/2019
Main author: 
Treviño-Morales, S. P.
IAA authors: 
González-García, M.
Authors: 
Treviño-Morales, S. P.;Fuente, A.;Sánchez-Monge, Á.;Kainulainen, J.;Didelon, P.;Suri, S.;Schneider, N.;Ballesteros-Paredes, J.;Lee, Y. -N.;Hennebelle, P.;Pilleri, P.;González-García, M.;Kramer, C.;García-Burillo, S.;Luna, A.;Goicoechea, J. R.;Tremblin, P.;Geen, S.
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
629
Pages: 
A81
Abstract: 
Context. High-mass stars and star clusters commonly form within hub-filament systems. Monoceros R2 (hereafter Mon R2), at a distance of 830 pc, harbors one of the closest of these systems, making it an excellent target for case studies. <BR /> Aims: We investigate the morphology, stability and dynamical properties of the Mon R2 hub-filament system. <BR /> Methods: We employed observations of the <SUP>13</SUP>CO and C<SUP>18</SUP>O 1 →0 and 2 →1 lines obtained with the IRAM-30 m telescope. We also used H<SUB>2</SUB> column density maps derived from Herschel dust emission observations. <BR /> Results: We identified the filamentary network in Mon R2 with the DisPerSE algorithm and characterized the individual filaments as either main (converging into the hub) or secondary (converging to a main filament). The main filaments have line masses of 30-100 M<SUB>☉</SUB> pc<SUP>-1</SUP> and show signs of fragmentation, while the secondary filaments have line masses of 12-60 M<SUB>☉</SUB> pc<SUP>-1</SUP> and show fragmentation only sporadically. In the context of Ostriker's hydrostatic filament model, the main filaments are thermally supercritical. If non-thermal motions are included, most of them are transcritical. Most of the secondary filaments are roughly transcritical regardless of whether non-thermal motions are included or not. From the morphology and kinematics of the main filaments, we estimate a mass accretion rate of 10<SUP>-4</SUP>-10<SUP>-3</SUP> M<SUB>☉</SUB> yr<SUP>-1</SUP> into the central hub. The secondary filaments accrete into the main filaments at a rate of 0.1-0.4 × 10<SUP>-4</SUP> M<SUB>☉</SUB> yr<SUP>-1</SUP>. The main filaments extend into the central hub. Their velocity gradients increase toward the hub, suggesting acceleration of the gas. We estimate that with the observed infall velocity, the mass-doubling time of the hub is 2.5 Myr, ten times longer than the free-fall time, suggesting a dynamically old region. These timescales are comparable with the chemical age of the HII region. Inside the hub, the main filaments show a ring- or a spiral-like morphology that exhibits rotation and infall motions. One possible explanation for the morphology is that gas is falling into the central cluster following a spiral-like pattern.
Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079457368&doi=10.1051%2f0004-6361%2f201935260&partnerID=40&md5=f396e1711aed987c5282423ac1d430d8
ADS Bibcode: 
2019A&A...629A..81T
Keywords: 
ISM: kinematics and dynamics;ISM: structure;ISM: clouds;ISM: individual objects: Monoceros R2;Astrophysics - Astrophysics of Galaxies