Multi-scale analysis of the Monoceros OB 1 star-forming region. II. Colliding filaments in the Monoceros OB1 molecular cloud

Abstract

Context. We started a multi-scale analysis of star formation in G202.3+2.5, an intertwined filamentary sub-region of the Monoceros OB molecular complex, in order to provide observational constraints o current theories and models that attempt to explain star formatio globally. In the first paper (Paper I), we examined the distributions o dense cores and protostars and found enhanced star formation activity i the junction region of the filaments. Aims: In this second paper we aim to unveil the connections between the core and filamen evolutions, and between the filament dynamics and the global evolutio of the cloud. Methods: We characterise the gas dynamics an energy balance in different parts of G202.3+2.5 using infrare observations from the Herschel and WISE telescopes and molecular tracer observed with the IRAM 30-m and TRAO 14-m telescopes. The velocity fiel of the cloud is examined and velocity-coherent structures ar identified, characterised, and put in perspective with the clou environment. Results: Two main velocity components are revealed, well separated in radial velocities in the north and merged around th location of intense N2H+ emission in the centre o G202.3+2.5 where Paper I found the peak of star formation activity. W show that the relative position of the two components along th sightline, and the velocity gradient of the N2H emission imply that the components have been undergoing collision fo 105 yr, although it remains unclear whether the gas move mainly along or across the filament axes. The dense gas wher N2H+ is detected is interpreted as the compresse region between the two filaments, which corresponds to a high mas inflow rate of 1 × 10-3 M☉ yr-1 an possibly leads to a significant increase in its star formatio efficiency. We identify a protostellar source in the junction regio that possibly powers two crossed intermittent outflows. We show that th H II region around the nearby cluster NCG 2264 is still expanding an its role in the collision is examined. However, we cannot rule out th idea that the collision arises mostly from the global collapse of th cloud. Conclusions: The (sub-)filament-scale observables examined in this paper reveal a collision between G202.3+2.5 sub-structures an its probable role in feeding the cores in the junction region. To she more light on this link between core and filament evolutions, one mus characterise the cloud morphology, its fragmentation, and magneti field, all at high resolution. We consider the role of the environmen in this paper, but a larger-scale study of this region is now necessar to investigate the scenario of a global cloud collapse. The reduce datacubes (FITS files) of our IRAM and TRAO observations are onl available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.f bin/cat/J/A+A/631/A3