The Formation of Massive Molecular Filaments and Massive Stars Triggered by a MHD Shock Wave

Inoue, Tsuyoshi; Hennebelle, P.; Fukui, Y.; Matsumoto, Toshiro; Iwasaki, Kazunari; Inutsuka, Shu‐ichiro

doi:10.48550/arxiv.1707.02035

Cited by 10 publications

(21 citation statements)

References 5 publications

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“…The northern part of the red cloud distributes likely to be enclosed by the blue cloud. The complementary distribution of the two clouds which harbors high-mass stars near the boundary between them is a characteristic structure recently has been found in several high-mass star-forming regions (e.g., Torii et al 2015;Fukui et al 2017;Torii et al 2017). Figure 4(d) indicates a longitude-velocity diagram with the integrated latitude from b = 1.425 • to 1.5 • as shown by the yellow dashed lines in the panel (c).…”

Section: Two Clouds At Different Velocitiessupporting

confidence: 52%

“…The cloud-cloud collision model can be also applied to the other high-mass star-forming regions in the Vela Molecular Ridge (RCW 38, Fukui et al 2016;RCW 32, Enokiya et al 2017 in prep;RCW 36, Sano et al 2017). Among these candidates summarized in Fukui et al (2017), RCW 34 with a single O star is characterized by the two clouds with relatively lower mass.…”

Section: Possible Scenarios To Form the Gas And Stellar Distributions...mentioning

confidence: 99%

“…Our observational results, however, are difficult to verify tiny gas structures due to the poor spatial and velocity resolutions. Future follow up observations by ASTE toward the southern area will provide the velocity feature of the whole clouds and ALMA observations of the colliding area are expected to resolve filamentary gas structures associated with the turbulent gas motions suggested by a numerical simulation Fukui 2013 andInoue et al 2017), which will be useful to finally probe that cloud-cloud collision is a relevant process in the formation of high-mass stars. showing a further morphological correspondence between the blue and red clouds.…”

Section: Possible Scenarios To Form the Gas And Stellar Distributions...mentioning

confidence: 99%

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High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

Hayashi

Sano

Enokiya

et al. 2018

Publications of the Astronomical Society of Japan

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We report a possibility that the high-mass star located in the HII region RCW 34 was formed by a triggering induced by a collision of molecular clouds. Molecular gas distributions of the 12 CO and 13 CO J =2-1, and 12 CO J =3-2 lines in the direction of RCW 34 were measured by using the NANTEN2 and ASTE telescopes. We found two clouds with the velocity ranges of 0-10 km s −1 and 10-14 km s −1 . Whereas the former cloud as massive as ∼1.4 × 10 4 M ⊙ has a morphology similar to the ring-like structure observed in the infrared wavelengths, the latter cloud with the mass of ∼600 M ⊙ , which has not been recognized by previous observations, distributes just likely to cover the bubble enclosed by the other cloud. The high-mass star with the spectral type of O8.5V is located near the boundary of the two clouds. The line intensity ratio of 12 CO J =3-2 / J =2-1 yields high values ( > ∼ 1.0), suggesting that these clouds 1 are associated with the massive star. We also confirmed that the obtained position-velocity diagram shows a similar distribution to that derived by a numerical simulation of the supersonic collision of two clouds. Using the relative velocity between the two clouds (∼5 km s −1 ), the collisional time scale is estimated to be ∼0.2 Myr with the assumption of the distance of 2.5 kpc. These results suggest that the high-mass star in RCW 34 was formed rapidly within a time scale of ∼0.2 Myr via a triggering of cloud-cloud collision.

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Section: Two Clouds At Different Velocitiessupporting

confidence: 52%

Section: Possible Scenarios To Form the Gas And Stellar Distributions...mentioning

confidence: 99%

Section: Possible Scenarios To Form the Gas And Stellar Distributions...mentioning

confidence: 99%

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High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

Hayashi

Sano

Enokiya

et al. 2018

Publications of the Astronomical Society of Japan

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“…In the CCC model, dense gas clumps are formed within the compressed layer at the interface of the collision, at which the bridge features at intermediate velocities and/or complementary distribution between two clouds can be seen unless the cloud dispersal by the stellar feedback is significant. The dense clumps gains high mass accretion rates such as 10 −4 -10 −3 M ⊙ yr −1 as demonstrated by Inoue et al (2017), which satisfies the theoretical requirement to overcome the radiation pressure feedback of the forming O star (e.g., Wolfire and Cassinelli The HVC 1 in N35 appears to be overlapping the peak of the 21 cm emission, at which the exciting source of N35 is possibly located, and it is consistent with the scenario that the high-mass star(s) in N35 was (were) formed at the colliding part between the LVC and HVC 1. HII region A1 is located at the western rim of the ring-like structure of the LVC, while HII region A2 is seen at the center of the HVC 2, suggesting that HII region A1 was formed on the side of the cavity created by the collision, while HII region A2 was born at the bottom of the cavity.…”

Section: High-mass Star Formation Triggered By Cccsmentioning

confidence: 89%

“…Habe and Ohta (1992) calculated a collision between two clouds with different sizes, followed by Anathpindika (2010) and Takahira, Tasker, and Habe (2014), indicating that CCC can induce formation of dense self-gravitating clumps within a dense gas layer compressed by collision. Formation of the massive clumps in the collisional-compressed layer was also discussed in depth in the magnetohydrodynamical (MHD) simulations by Inoue and Fukui (2013) and Inoue et al (2017). Wu et al (2017) discussed that collision between GMCs increases star formation rate and efficiency.…”

Section: Introductionmentioning

confidence: 99%

Large-scale CO J = 1–0 observations of the giant molecular cloud associated with the infrared ring N35 with the Nobeyama 45 m telescope

Torii

Fujita

Matsuo

et al. 2018

Publications of the Astronomical Society of Japan

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We report an observational study of the giant molecular cloud (GMC) associated with the Galactic infrared ring-like structure N35 and two nearby HII regions G024.392+00.072 (HII region A) and G024.510-00.060 (HII region B), using the new CO J=1-0 data obtained as a 1 part of the FOREST Unbiased Galactic Plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) project at a spatial resolution of 21 ′′ . Our CO data revealed that the GMC, with a total molecular mass of 2.1 × 10 6 M ⊙ , has two velocity components over ∼10-15 km s −1 .The majority of molecular gas in the GMC is included in the lower-velocity component (LVC)at ∼110-114 km s −1 , while the higher-velocity components (HVCs) at ∼118-126 km s −1 consist of three smaller molecular clouds which are located near the three HII regions. The LVC and HVCs show spatially complementary distributions along the line-of-sight, despite large velocity separations of ∼5-15 km s −1 , and are connected in velocity by the CO emission with intermediate intensities. By comparing the observations with simulations, we discuss a scenario where collisions of the three HVCs with LVC at velocities of ∼10-15 km s −1 can provide an interpretation of these two observational signatures. The intermediate velocity features between the LVC and HVCs can be understood as broad bridge features, which indicate the turbulent motion of the gas at the collision interfaces, while the spatially complementary distributions represent the cavities created in the LVC by the HVCs through the collisions. Our model indicates that the three HII regions were formed after the onset of the collisions, andit is therefore suggested that the high-mass star formation in the GMC was triggered by the collisions.

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Characterizing the properties of nearby molecular filaments observed withHerschel

Arzoumanian

André

Könyves

et al. 2019

A&A

202

357

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Context. Molecular filaments have received special attention recently, thanks to new observational results on their properties. In particular, our early analysis of filament properties from Herschel imaging data in three nearby molecular clouds revealed a narrow distribution of median inner widths centered at a characteristic value of about 0.1 pc. Aims. Here, we extend and complement our initial study with a detailed analysis of the filamentary structures identified with Herschel in eight nearby molecular clouds (at distances <500 pc). Our main goal is to establish statistical distributions of median properties averaged along the filament crests and to compare the results with our earlier work based on a smaller number of filaments. Methods. We use the column density (N H 2 ) maps derived from Herschel data and the DisPerSE algorithm to trace a network of individual filaments in each cloud. We analyze the density structure along and across the main filament axes in detail. We build synthetic maps of filamentary clouds to assess the completeness limit of our extracted filament sample and validate our measurements of the filament properties. These tests also help us to select the best choice of parameters to be used for tracing filaments with DisPerSE and fitting their radial column density profiles. Results. Our analysis yields an extended sample of 1310 filamentary structures and a selected sample of 599 filaments with aspect ratios larger than 3 and column density contrasts larger than 0.3. We show that our selected sample of filaments is more than 95 % complete for column density contrasts larger than 1, with only ∼ 5 % of spurious detections. On average, more than 15 % of the total gas mass in the clouds, and more than 80 % of the dense gas mass (at N H 2 > 7 × 10 21 cm −2 ), is found to be in the form of filaments, respectively. Analysis of the radial column density profiles of the 599 filaments in the selected sample indicates a narrow distribution of crest-averaged inner widths, with a median value of 0.10 pc and an interquartile range of 0.07 pc. In contrast, the extracted filaments span wide ranges in length, central column density, column density contrast, and mass per unit length. The characteristic filament width is well resolved by Herschel observations, and a median value of ∼0.1 pc is consistently found using three distinct estimates based on (1) a direct measurement of the width at half power after background subtraction, as well as (2) Gaussian and (3) Plummer fits. The existence of a characteristic filament width is further supported by the presence of a tight correlation between mass per unit length and central column density for the observed filaments. Conclusions. Our detailed analysis of a large filament sample confirms our earlier result that nearby molecular filaments share a common mean inner width of ∼0.1 pc, with typical variations along and on either side of the filament crests of about ±0.06 pc around the mean value. This observational result sets strong constraints on possible models...

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The Formation of Massive Molecular Filaments and Massive Stars Triggered by a MHD Shock Wave

Cited by 10 publications

References 5 publications

High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

Large-scale CO J = 1–0 observations of the giant molecular cloud associated with the infrared ring N35 with the Nobeyama 45 m telescope

Characterizing the properties of nearby molecular filaments observed withHerschel

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