Evolution of the Hub-filament Structures in IC 5146 in the Context of the Energy Balance of Gravity, Turbulence, and Magnetic Field

Abstract

We present the results of 850 μm polarization and C18O (3 − 2) line observations toward the western hub-filament structure (W-HFS) of the dark Streamer in IC 5146 using the James Clerk Maxwell Telescope SCUBA-2/POL-2 and HARP instruments. We aim to investigate how the relative importance of the magnetic field, gravity, and turbulence affects core formation in HFS by comparing the energy budget of this region. We identified four 850 μm cores and estimated the magnetic field strengths (B pos) of the cores and the hub and filament using the Davis–Chandrasekhar–Fermi method. The estimated B pos is ∼80 to 1200 μG. From Wang et al., B pos of E-47, a core in the eastern hub (E-hub), and E-hub were reestimated to be 500 and 320 μG, respectively, with the same method. We measured the gravitational (E G), kinematic (E K), and magnetic energies (E B) in the filament and hubs and compared the relative importance among them. We found that an E B-dominant filament has aligned fragmentation type, while E G-dominant hubs show no and clustered fragmentation types. In the E G dominant hubs, it seems that the portion of E K determines whether the hub becomes to have clustered (the portion of E K ∼ 20%) or no fragmentation type (∼10%). We propose an evolutionary scenario for the E- and W-HFSs, where the HFS forms first by the collision of turbulent flows, and then the hubs and filaments can go into various types of fragmentation depending on their energy balance of gravity, turbulence, and magnetic field.

IC 5146 Dark Streamer: The First Reliable Candidate of Edge Collapse, Hub-filament Systems, and Intertwined Sub-filaments

“…These observations are consistent with the theoretical outcomes stating that the magnetic field supports the filament against collapsing into its longer axis and guides the gravity-driven gas contraction (e.g., Nakamura & Li 2008;Inutsuka et al 2015). A curved magnetic field morphology was investigated toward both ends of IC 5146 (Wang et al 2019;Chung et al 2022), and was proposed to be an indication of the EDC process in long filaments. However, such signature has not yet been assessed in potential and nearby EDC filaments.…”

“…Using a multiwavelength approach, a few SFRs have been identified and reported, where the edge collapse and the HFSs have been simultaneously investigated (e.g., G45.3 +0. 1 Bhadari et al 2022; IC 5146 dark streamer Wang et al 2019;Chung et al 2022). In such cases, an HFS is observed toward each edge of the EDC filament.…”

“…In SFRs, a system of filaments converging to a central hub, which is referred to as a hub-filament system (HFS; Myers 2009), is a commonly observed feature, where young stellar objects (YSOs) and massive OB stars (M  8 M e ) are born. Furthermore, researchers have also identified isolated filaments undergoing end-dominated collapse (EDC) or edge collapse (Bastien 1983;Pon et al 2012;Clarke & Whitworth 2015), and observational evidence of such EDC filaments is gradually increasing in the literature (e.g., NGC 6334 (Zernickel et al 2013), Sh 2-242 (or S242; Dewangan et al 2019;Yuan et al 2020), IC 5146 (Wang et al 2019;Chung et al 2022), Mon R1 (or Mon R1; Bhadari et al 2020), G341.244-00.265 (Yu et al 2019), and G45.3+0.1 (Bhadari et al 2022)). Using a multiwavelength approach, a few SFRs have been identified and reported, where the edge collapse and the HFSs have been simultaneously investigated (e.g., G45.3 +0.…”

“…Dust continuum maps revealed the long filamentary morphology of the IC 5146 dark streamer (Kramer et al 2003), and two prominent HFSs were investigated toward the eastern and the western parts (i.e., E-HFS and W-HFS) of the streamer (e.g., Arzoumanian et al 2011Arzoumanian et al , 2019Roy et al 2011;Johnstone et al 2017;Wang et al 2017Wang et al , 2019Wang et al , 2020bChung et al 2021Chung et al , 2022. Several polarimetry studies were conducted toward the IC 5146 dark streamer (Wang et al 2017(Wang et al , 2019(Wang et al , 2020bChung et al 2022), which allowed for the exploration of magnetic field structures. These earlier works showed the presence of uniform magnetic field vectors perpendicular to the dark streamer.…”

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

“…The relative orientation of magnetic field with the expansion of the HII region influences not only the density of the shell but also its fragmentation and core formation (Chen et al 2022). Some studies have examined the role and significance of magnetic fields in cloud evolution and star formation and have shown that the magnetic fields can be aligned tangential to the shells of evolved HII regions (e.g., Pereyra & Magalhaes 2007;Tang et al 2009;Chen et al 2012Chen et al , 2017Santos et al 2014;Fissel et al 2016;Soam et al 2017Soam et al , 2018Eswaraiah et al 2017;Pattle et al 2018;Dewangan et al 2018;Eswaraiah et al 2020; Könyves et al 2021;Devaraj et al 2021;Fernández-López et al 2021;Hoang et al 2022;Chung et al 2022). This tangential field morphology is also predicted in some theoretical simulations (Krumholz et al 2007;Henney et al 2009;Arthur et al 2011;Ntormousi et al 2017).…”