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Gas kinematics in high-mass star-forming regions from the Perseus spiral arm

M. S. Kirsanova ; A. M. Sobolev ; Magnus Thomasson (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium)
Astronomy Reports (1063-7729). Vol. 61 (2017), 9, p. 760-774.
[Artikel, refereegranskad vetenskaplig]

We present results of a survey of 14 star-forming regions from the Perseus spiral armin CS (2-1) and (CO)-C-13 (1-0) lines with the Onsala Space Observatory 20 m telescope. Maps of 10 sources in both lines are obtained. For the remaining sources a map in just one line or a single-point spectrum is obtained. On the basis of newly obtained and published observational data we consider the relation between velocities of the "quasi-thermal" CS (2-1) line and 6.7 GHz methanol maser line in 24 high-mass star-forming regions in the Perseus arm. We show that, surprisingly, velocity ranges of 6.7 GHz methanol maser emission are predominantly red-shifted with respect to corresponding CS (2-1) line velocity ranges in the Perseus arm. We suggest that the predominance of the "red-shifted masers" in the Perseus arm could be related to the alignment of gas flows caused by the large-scalemotions in the Galaxy. Large-scale galactic shock related to the spiral structure is supposed to affect the local kinematics of the star-forming regions. Part of the Perseus arm, between galactic longitudes from 85A degrees to 124A degrees , does not contain blue-shifted masers at all. Radial velocities of the sources are the greatest in this particular part of the arm, so the velocity difference is clearly pronounced. (CO)-C-13 (1-0) and CS (2-1) velocity maps of G183.35-0.58 show gas velocity difference between the center and the periphery of the molecular clump up to 1.2 km s(-1). Similar situation is likely to occur in G85.40-0.00. This can correspond to the case when the large-scale shock wave entrains the outer parts of a molecular clump in motion while the dense central clump is less affected by the shock.

Nyckelord: H-Ii Regions, 6.7-Ghz Methanol Masers, Young Stellar Objects, 6.7 Ghz, Molecular Cloud, Galactic Plane, Milky-Way, Noncircular Motions, Hii-Regions



Denna post skapades 2017-09-25. Senast ändrad 2018-01-12.
CPL Pubid: 252054

 

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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium (2010-2017)

Ämnesområden

Astronomi, astrofysik och kosmologi

Chalmers infrastruktur