Dense Molecular Clumps Associated with Young Clusters in Massive Star‐forming Regions

Saito, Hiro; Saito, Masao; Sunada, Kazuyoshi; Yonekura, Yoshinori

doi:10.1086/512058

Cited by 42 publications

(107 citation statements)

References 48 publications

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“…Three massive clumps were identified in the region by Saito et al (2007). The most massive one named MCS B coincides with the MM1 clump (M ≈ 50 M ) detected at 1.2-mm by Minier et al (2005).…”

Section: Iras 06058+2138-nirsmentioning

confidence: 60%

“…The most massive one named MCS B coincides with the MM1 clump (M ≈ 50 M ) detected at 1.2-mm by Minier et al (2005). The massive YSO NIRS 1 (V C 18 O lsr = +3.9 km s −1 , Saito et al 2007;Tamura et al 1991) is associated with MCS B and is also the 6.7-GHz CH 3 OH maser site (Minier et al 2000;Xu et al 2009). The CH 3 OH masers show a linear distribution of 120 mas with a roughly linear velocity gradient along it, although a few masers following a different velocity distribution (Minier et al 2000).…”

Section: Iras 06058+2138-nirsmentioning

confidence: 83%

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EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Surcis

Vlemmings

Langevelde

et al. 2013

A&A

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Context. Magnetic fields have only recently been included in theoretical simulations of high-mass star formation. The simulations show that magnetic fields play an important role in the formation and dynamics of molecular outflows. Masers, in particular 6.7-GHz CH 3 OH masers, are the best probes of the magnetic field morphologies around massive young stellar objects on the smallest scales of 10-100 AU. Aims. Providing new observational measurements of the morphology of magnetic fields around massive young stellar objects by using 6.7-GHz CH 3 OH maser emission is very important for setting constraints on the numerical simulations of massive star formation. Methods. This paper focuses on 4 massive young stellar objects, IRAS 06058+2138-NIRS 1, IRAS 22272+6358A, S255-IR, and S231, which complement our previous 2012 sample (the first EVN group). From all these sources, molecular outflows have been detected in the past. Seven of the European VLBI Network antennas were used to measure the linear polarization and Zeeman-splitting of the 6.7-GHz CH 3 OH masers in the star-forming regions in this second EVN group. Results. We detected a total of 128 CH 3 OH masing cloudlets. Fractional linear polarization (0.8%-11.3%) was detected towards 18% of the CH 3 OH masers in our sample. The linear polarization vectors are well ordered in all the massive young stellar objects. We measured significant Zeeman-splitting in IRAS 06058+2138-NIRS 1 (ΔV Z = 3.8 ± 0.6 m s −1 ) and S255-IR (ΔV Z = 3.2 ± 0.7 m s −1 ). Conclusions. By considering the 20 massive young stellar objects towards which the morphology of magnetic fields was determined by observing 6.7-GHz CH 3 OH masers in both hemispheres, we find no evident correlation between the linear distributions of CH 3 OH masers and the outflows or the linear polarization vectors. On the other hand, we present first statistical evidence that the magnetic field (on scales 10-100 AU) is primarily oriented along the large-scale outflow direction. Moreover, we empirically find that the linear polarization fraction of unsaturated CH 3 OH masers is P l < 4.5%.

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Section: Iras 06058+2138-nirsmentioning

confidence: 60%

Section: Iras 06058+2138-nirsmentioning

confidence: 83%

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Surcis

Vlemmings

Langevelde

et al. 2013

A&A

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“…Previous studies (e.g., Umemoto et al 2002;Saito et al 2006Saito et al , 2007 indicated that the clumps have a size scale of ∼ 0.3 pc and the cores have a size scale of ∼ 0.03 pc. The physical quantities of the dense gas in the cluster-forming regions, including massive star formations, are derived from the C 18 O-line emission.…”

Section: Derivation Of Physical Properties Of the Coresmentioning

confidence: 93%

“…Recently, many young embedded clusters within molecular clouds have been discovered by infrared observations (e.g., Bica et al 2003). On the basis of these observations, to investigate the physical conditions in the dense gas that forms rich clusters, dense molecular gas surveys were carried out on such young clusters that include massive stars, revealing that clusters are formed in gas systems with a size scale of a cluster (∼ 0.3 pc) in GMCs (e.g., Lada 1992;Lada & Lada 2003;Saito et al 2007) and these systems are usually called "clumps." However, a few very compact gas systems having a size scale of ∼ 0.03 pc similar to typical (cold) cores in lowmass star-forming regions (e.g., Onishi et al 2002;Umemoto et al 2002) have been discovered with very high-angular-resolution observations using an interferometer on young clusters that include massive (proto)stars (e.g., Churchwell et al 1992;Olmi et al 1993).…”

Section: Introductionmentioning

confidence: 99%

“…If this multiple-core system is formed by the fragmentation of the inner structure of the clump, a close relationship should exist between the physical parameters of the clump and the characteristics of the formed cluster. Saito et al (2007) carried out molecular line observations using the Nobeyama 45-m telescope directed toward the clumps in several cluster-forming regions and suggested that a good relationship indeed exists between the average H 2 density of the clumps and the stellar number density of formed clusters in these clumps. In addition, they found a good correlation between the line width of the clumps and the maximum mass of formed stars.…”

Section: Introductionmentioning

confidence: 99%

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High‐Resolution Studies of the Multiple‐Core Systems toward Cluster‐forming Regions Including Massive Stars

Saito

Yonekura

et al. 2008

ASTROPHYS J SUPPL S

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We present the results of C 18 O observations by the Nobeyama Millimeter Array toward dense clumps with radii of ∼ 0.3 pc in six cluster-forming regions including massive (proto)stars. We identified 171 cores, whose radius, line width, and molecular mass range from 0.01 to 0.09 pc, 0.43 to 3.33 km s −1 , and 0.5 to 54.1 M ⊙ , respectively. Many cores with various line widths exist in one clump, and the index of the line width-radius relationship of the cores and the parental clump differs from core to core in the clump. This indicates that the degree of dissipation of the turbulent motion varies for each core in one clump. Although the mass of the cores increases with the line width, most cores are gravitationally bound by the external pressure. In addition, the line width and the external pressure of the cores tend to decrease with the distance from the center of the clump, and these dependencies may be caused by the inner H 2 density structure of the clump that affects the physical properties of the cores. Moreover, the number density of the cores and the number density of young (proto)stars have a similar relationship to the average H 2 density of the clumps. Thus, our findings suggest that the cluster is formed in the clump through the formation of such multiple cores, whose physical properties would have been strongly related to the H 2 density structure and the turbulent motion of the clump.

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Star-forming site RAFGL 5085: Is a perfect candidate of hub-filament system?

et al. 2023

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Dense Molecular Clumps Associated with Young Clusters in Massive Star‐forming Regions

Cited by 42 publications

References 48 publications

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

High‐Resolution Studies of the Multiple‐Core Systems toward Cluster‐forming Regions Including Massive Stars

Star-forming site RAFGL 5085: Is a perfect candidate of hub-filament system?

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