CO (J = 1–0) Observations toward Filamentary Molecular Clouds in the Galactic Region with l = [169.°75, 174.°75], b = [−0.°75, 0.°5]

Abstract

We present observations of the CO isotopologues (12 CO, 13 CO, and C 18 O) toward the Galactic region with 169°.75l174°.75 and −0°.75b0°.5 using the Purple Mountain Observatory 13.7 m millimeterwavelength telescope. Based on the 13 CO(J = 1 − 0) data, we find five molecular clouds within the velocity range between −25 and 8 km s −1 that are all characterized by conspicuous filamentary structures. We have identified eight filaments with a length of 6.38-28.45 pc, a mean H 2 column density of 0.70×10 21-6.53×10 21 cm −2 , and a line mass of 20.24-161.91M ☉ pc −1 , assuming a distance of ∼1.7kpc. Gaussian fittings to the inner parts of the radial density profiles lead to a mean FWHM width of 1.13±0.01 pc. The velocity structures of most filaments present continuous distributions with slight velocity gradients. We find that turbulence is the dominant internal pressure to support the fragmentation of filaments instead of thermal pressure. Most filaments have virial parameters smaller than 2; thus, they are gravitationally bound. Four filaments have an LTE line mass close to the virial line mass. We further extract dense clumps using the 13 CO data and find that 64% of the clumps are associated with the filaments. According to the complementary IR data, most filaments have associated ClassII young stellar objects. ClassI objects are mainly found to be located in the filaments with a virial parameter close to 1. Within two virialized filaments, 12 CO outflows have been detected, indicating ongoing star-forming activity therein.

Large-scale CO (J = 1–0) Observations toward the M120.1+3.0 Molecular Cloud: A Filament with a Chain of Starburst Clusters

“…The dashed red lines are the results of Gaussian fitting, from which we estimate the full width at half maximum (FWHM) width of each filament (see Table 1). The measured FWHM widths of our sample are between 0.9-1.7 pc, which are similar to the results derived from the MWISP surveys (e.g., Xiong et al 2017Xiong et al , 2019. Arzoumanian et al (2011) suggested that the filament width has a typical value of ∼0.1 pc based on the Herschel observations (but see also Panopoulou et al 2022).…”

Local Molecular Gas toward the Aquila Rift Region

“…Several filamentary structures with somewhat different velocities seem to just overlap on the Serpens NE region, which is also seen by Nakamura et al (2017) according to 12 CO (J=2-1) and 13 CO (J=2-1) data. Systematic analysis of these filaments will be presented in future works by using some algorithms on the 3D 13 CO and C 18 O data cubes (e.g., see discussions in Xiong et al 2017Xiong et al , 2019.…”

A wide-field CO survey towards the California Molecular Filament

“…The mean M line estimated from the enclosed M line profile (see Figure 6) is ∼ 26 M ⊙ pc −1 , which is larger than the critical line mass (M line,crit = 2 υ 2 /G ∼ 464 (∆V ) 2 ≈ 16.7 M ⊙ pc −1 ) dominated by thermal support (∆V ∼ c s ≈ 0.19 km s −1 ) and less than the critical line mass (∼ 335.2 M ⊙ pc −1 ) dominated by turbulent support (∆V ∼ σ tot ≈ 0.85 km s −1 ) (see Figure 7). The detailed calculation method of the isothermal sound speed c s and σ tot was introduced in Xiong et al (2017Xiong et al ( , 2019. It indicates that the CMF is under the gravitationally unstable conditions and should fragment into dense cores, as we see in the C 18 O images.…”

“…This unbiased survey provides us a good opportunity to study large-scale filamentary molecular clouds, as well as star formation therein (see, e.g. Xiong et al 2019). As a part of the MWISP survey, we present in this work the results of the three CO (J=1-0) isotopologue line observations toward the CMC.…”