DOI:
10.1051/0004-6361/201935260
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
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.
URL:
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079457368&doi=10.1051%2f0004-6361%2f201935260&partnerID=40&md5=f396e1711aed987c5282423ac1d430d8
Keywords:
ISM: kinematics and dynamics;ISM: structure;ISM: clouds;ISM: individual objects: Monoceros R2;Astrophysics - Astrophysics of Galaxies