Influence of Shear Motion on Evolution of Molecular Clouds in the Spiral Galaxy M51

Abstract

We have investigated the dynamics of the molecular gas and the evolution of GMAs in the spiral galaxy M51 with the NRO 45-m telescope. The velocity components of the molecular gas perpendicular and parallel to the spiral arms are derived at each spiral phase from the distribution of the line-of-sight velocity of the CO gas. In addition, the shear motion in the galactic disk is determined from the velocity vectors at each spiral phase. It is revealed that the distributions of the shear strength and of GMAs are anti-correlated. GMAs exist only in the area of the weak shear strength and further on the upstream side of the high shear strength. GMAs and most of GMCs exist in the regions where the shear critical surface density is smaller than the gravitational critical surface density, indicating that they can stably grow by self-gravity and the collisional agglomeration of small clouds without being destroyed by shear motion. These indicate that the shear motion is an important factor in evolution of GMCs and GMAs.

28pages, 23 figures, accepted for publication in PASJ

References in corpus (5)

• Dynamically Driven Evolution of the Interstellar Medium in M51
• A complete 12CO 2-1 map of M51 with HERA: I. Radial averages of CO, HI, and radio continuum
• Kinematics of Spiral Arm Streaming in M51
• Radial Dependence of the Pattern Speed of M51
• A CO J=3-2 map of M51 with HARP-B: Radial properties of the spiral structure

Cited by in corpus (20)

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• Radial distributions of arm-gas offsets as an observational test of spiral theories
• FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45-m Telescope (FUGIN) V: Dense gas mass fraction of molecular gas in the Galactic plane
• ALMA Observations of Giant Molecular Clouds in M33 I: Resolving Star Formation Activities in the Giant Molecular Filaments Possibly Formed by a Spiral Shock
• How do velocity structure functions trace gas dynamics in simulated molecular clouds?
• Variation in GMC Association Properties Across Bars, Spiral Arms, Inter-Arms, and Circumnuclear Region of M100 (NGC 4321) Extracted from ALMA Observations
• The changing GMC population in galaxy interactions
• Molecular Distribution in the Spiral Arm of M51
• A SOFIA Survey of [CII] in the galaxy M51 II. [CII] and CO kinematics across spiral arms
• Nobeyama 45 m Local Spur CO survey. I. Giant molecular filaments and cluster formation in the Vulpecula OB association
• Molecular clouds in M51 from high-resolution extinction mapping
• The Evolution of Interacting Spiral Galaxy NGC 5194
• A tale of two nearby dwarf irregular galaxies WLM and IC 2574 -- as revealed by UVIT
• Morphology and kinematics of the gas in M51: How interaction with NGC5195 has moulded the structure of its arms
• ACA CO(J=2-1) Mapping of the Nearest Spiral Galaxy M33. II. Exploring the Evolution of Giant Molecular Clouds
• Cloud populations versus galactic environment in NGC4689, NGC628, NGC1566, and NGC4321
• Molecular cloud matching in CO and dust in M33 II. Physical properties of giant molecular clouds