TRAO Survey of Nearby Filamentary Molecular Clouds, the Universal Nursery of Stars (TRAO FUNS). I. Dynamics and Chemistry of L1478 in the California Molecular Cloud

Chung, Eun Jung; Lee, Chang-Won; Kim, Shinyoung; Kim, Gwanjeong; Caselli, P.; Tafalla, M.; Myers, Philip C.; Soam, Archana; Maheswar, G.; Kim, Miryang; Kim, Kyoung Hee; Kwon, Woojin; Kang, Heau-Jo

doi:10.3847/1538-4357/ab12d1

“…The physical and kinematic characteristics of the filaments identified in L1544 and L694-2 are found to be consistent with those seen in filaments with embedded cores in the low-mass star-forming region (Hacar & Tafalla 2011). In particular, they have physical properties significantly similar to those of the small-scale, velocity-coherent filamentary structures, also called "fibers," found by decomposing techniques in turbulent large-scale filaments (e.g., Hacar et al 2013;Chung et al 2019).…”

Section: Discussionsupporting

confidence: 65%

The Role of Filamentary Structures in the Formation of Two Dense Cores, L1544 and L694-2

Kim

¹

,

Lee

²

,

Tafalla

³

et al. 2022

ApJ

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We present mapping results of two prestellar cores, L1544 and L694-2, embedded in filamentary clouds in C18O (3–2), 13CO (3–2), 12CO (3–2), HCO+ (4–3), and H13CO+ (4–3) lines with the James Clerk Maxwell Telescope to examine the role of the filamentary structures in the formation of dense cores in the clouds, with new distance estimates for L1544 ( 175 − 3 + 4 pc) and L694-2 ( 203 − 7 + 6 pc). From these observations, we found that the nonthermal velocity dispersion of two prestellar cores and their surrounding clouds is smaller than or comparable to the sound speed. This may indicate that the turbulence has already been dissipated for both filaments and cores during their formation time. We also found a λ/4 shift between the periodic oscillations in the velocity and the column density distributions, implying the possible presence of gravitational core-forming flow motion along the axis of the filament. The mass accretion rates due to these flow motions are estimated to be 2–3 M ⊙ Myr−1, being comparable to that for Serpens cloud but much smaller than those for the Hub filaments, cluster, or high-mass forming filaments by 1 or 2 orders of magnitude. From this study, we suggest that the filaments in our targets might be formed from the shock compression of colliding clouds, and then the cores are formed by gravitational fragmentation of the filaments to evolve to the prestellar stage. We conclude that the filamentary structures in the clouds play an important role in the entire process of formation of dense cores and their evolution.

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“…Stars are known to mainly form in the dense clumps/cores which have been developed in filamentary molecular clouds (e.g., André et al 2010). Hence, painstaking efforts have been made to find how filaments and dense cores form and evolve (e.g., Arzoumanian et al 2019;Chung et al 2019). Though still being under debate in detail, it is suggested that the molecular filaments first form by the dissipation of large-scale turbulence and then the dense clumps/cores are generated in the gravitationally supercritical filaments via fragmentation (André et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Chung

¹

,

Lee

²

,

Kwon

³

et al. 2022

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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.

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“…The CMC was firstly identified as a coherent elongated cloud at a single distance by wide-field infrared extinction maps from 2MASS (Lada et al 2009). In the following observations toward the CMC, pc-scale filaments are identified in subregions (Li et al 2014;Chung et al 2019;Zhang et al 2020). In this work, as shown in Figures 2 and 4, a 72 pc long filament extends continuously in space and velocity and stretch across these subregions.…”

Section: Large-scale Major Filament In the Cmcmentioning

confidence: 54%

“…Broekhoven-Fiene et al (2018) identified a sample of protostellar objects by the 850 µm and 450 µm observations using the SCUBA-2 as part of the JCMT Gould Belt Legacy Survey. Chung et al (2019) performed observations of molecular lines in the frequency range of 85−115 GHz to study the kinematics of the filaments and chemical evolution of the dense cores toward the L1478 region. However, the studies mentioned above mainly focused on the small filamentary structures and dynamic properties in the subregions of the CMC, and there is currently a lack of study on the structure and dynamics of this molecular cloud as a whole.…”

Section: Introductionmentioning

confidence: 99%

A wide-field CO survey towards the California Molecular Filament

Guo,

Chen,

Feng

et al. 2021

Preprint

0

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We present the survey of 12 CO/ 13 CO/C 18 O (J=1-0) toward the California Molecular Cloud (CMC) within the region of 161.75 • l 167.75 • , -9.5 • b -7.5 • , using the Purple Mountain Observatory (PMO) 13.7 m millimeter telescope. Adopting a distance of 470 pc, the mass of the observed molecular cloud estimated from 12 CO, 13 CO, and C 18 O is about 2.59×10 4 M ⊙ , 0.85×10 4 M ⊙ , and 0.09×10 4 M ⊙ , respectively. A large-scale continuous filament extending about 72 pc is revealed from the 13 CO images. A systematic velocity gradient perpendicular to the major axis appears and is measured to be ∼ 0.82 km s −1 pc −1 . The kinematics along the filament shows an oscillation pattern with a fragmentation wavelength of ∼ 2.3 pc and velocity amplitude of ∼ 0.92 km s −1 , which may be related with coreforming flows. Furthermore, assuming an inclination angle to the plane of the sky of 45 • , the estimated average accretion rate is ∼ 101 M ⊙ Myr −1 for the cluster LkHα 101 and ∼ 21 M ⊙ Myr −1 for the other regions. In the C 18 O observations, the large-scale filament could be resolved into multiple substructures and their dynamics are consistent with the scenario of filament formation from converging flows. Approximately 225 C 18 O cores are extracted, of which 181 are starless cores. Roughly 37 % (67/181) of the starless cores have α vir less than 1. Twenty outflow candidates are identified along the filament. Our results indicate active early-phase star formation along the large-scale filament in the CMC region.

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TRAO Survey of Nearby Filamentary Molecular Clouds, the Universal Nursery of Stars (TRAO FUNS). I. Dynamics and Chemistry of L1478 in the California Molecular Cloud

Cited by 15 publications

References 116 publications

The Role of Filamentary Structures in the Formation of Two Dense Cores, L1544 and L694-2

The Role of Filamentary Structures in the Formation of Two Dense Cores, L1544 and L694-2

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

A wide-field CO survey towards the California Molecular Filament

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