Structural and Dynamical Analysis of the Quiescent Molecular Ridge in the Large Magellanic Cloud

Abstract

We present a comparison of low-J 13CO and CS observations of four different regions in the LMC -- the quiescent Molecular Ridge, 30 Doradus, N159, and N113, all at a resolution of $\sim 3$ pc. The regions 30 Dor, N159, and N113 are actively forming massive stars, while the Molecular Ridge is forming almost no massive stars, despite its large reservoir of molecular gas and proximity to N159 and 30 Dor. We segment the emission from each region into hierarchical structures using dendrograms and analyze the sizes, masses, and linewidths of these structures. We find that the Ridge has significantly lower kinetic energy at a given size scale and also lower surface densities than the other regions, resulting in higher virial parameters. This suggests that the Ridge is not forming massive stars as actively as the other regions because it has less dense gas and not because collapse is suppressed by excess kinetic energy. We also find that these physical conditions and energy balance vary significantly within the Ridge and that this variation appears only weakly correlated with distance from sites of massive star formation such as R136 in 30 Dor, which is $\sim 1$ kpc away. These variations also show only a weak correlation with local star formation activity within the clouds.

arXiv comment18 pages, 17 figures, accepted to AJ

References in corpus (47)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Global Schmidt Law in Star Forming Galaxies
• The CO-to-H2 Conversion Factor
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• The Calibration of Mid-Infrared Star Formation Rate Indicators
• On the Star Formation Rates in Molecular Clouds
• Spitzer Survey of the Large Magellanic Cloud, Surveying the Agents of a Galaxy's Evolution (SAGE) I: Overview and Initial Results
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• Structural Analysis of Molecular Clouds: Dendrograms
• The Formation of a Bound Star Cluster: From the Orion Nebula Cluster to the Pleiades
• Variations in the Galactic star formation rate and density thresholds for star formation
• The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System and Implications for Magellanic Irregulars
• Third-Epoch Magellanic Cloud Proper Motions II: The Large Magellanic Cloud Rotation Field in Three Dimensions
• The Second Survey of the Molecular Clouds in the Large Magellanic Cloud by NANTEN I: Catalog of Molecular Clouds
• A Fractal Analysis of the HI Emission from the Large Magellanic Cloud
• When Feedback Fails: The Scaling and Saturation of Star Formation Efficiency
• High and Intermediate-Mass Young Stellar Objects in the Large Magellanic Cloud
• Formation of the Young Massive Cluster R136 triggered by Tidally-driven Colliding HI Flows
• Hubble Tarantula Treasury Project. III. Photometric Catalog and Resulting Constraints on the Progression of Star Formation in the 30 Doradus Region
• Some Constraints on The Formation of Globular Clusters
• Does External Pressure Explain Recent Results for Molecular Clouds?
• Hubble Tarantula Treasury Project: Unraveling Tarantula's Web. II. Optical and Near Infrared Star Formation History of the Starburst Cluster NGC 2070 in 30 Doradus
• The Physical Conditions in a Pre Super Star Cluster Molecular Cloud in the Antennae Galaxies
• An ALMA view of molecular filaments in the Large Magellanic Cloud II: An early stage of high-mass star formation embedded at colliding clouds in N159W-South
• Spitzer View of Young Massive Stars in the LMC HII Complexes. II. N159
• The Proper Motion Field Along the Magellanic Bridge: a New Probe of the LMC-SMC Interaction
• An ALMA view of molecular filaments in the Large Magellanic Cloud I: The formation of high-mass stars and pillars in the N159E-Papillon Nebula triggered by a cloud-cloud collision
• The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds
• The recent LMC-SMC collision: Timing and impact parameter constraints from comparison of Gaia LMC disk kinematics and N-body simulations
• The Life and Death of Dense Molecular Clumps in the Large Magellanic Cloud
• The CO-dark molecular gas mass in 30 Doradus
• The youngest massive protostars in the Large Magellanic Cloud
• The 30 Doradus Molecular Cloud at 0.4 pc Resolution with the Atacama Large Millimeter/submillimeter Array: Physical Properties and the Boundedness of CO-emitting Structures
• Forming clusters within clusters: How 30 Doradus recollapsed and gave birth again
• Relations Between Molecular Cloud Structure Sizes and Line Widths in the Large Magellanic Cloud
• Fractal dimension of interstellar clouds: opacity and noise effects
• The VMC Survey. XXIX. Turbulence-Controlled Hierarchical Star Formation in the Small Magellanic Cloud
• New Insights into the Physical Conditions and Internal Structure of a Candidate Proto-Globular Cluster
• Studying Relation Between Star Formation and Molecular Clumps on Subparsec Scales in 30 Doradus
• Integral Field Spectroscopy of Massive Young Stellar Objects in the N113 H\,{\sc ii} Region in the Large Magellanic Cloud
• An ALMA study of the massive molecular clump N159W-North in the Large Magellanic Cloud: A possible gas flow penetrating one of the most massive protocluster systems in the Local Group
• Structural and Dynamical Analysis of 0.1pc Cores and Filaments in the 30~Doradus-10 Giant Molecular Cloud
• The VMC survey -- XLVII. Turbulence-Controlled Hierarchical Star Formation in the Large Magellanic Cloud
• Extinction and dust/gas ratio in the H I ridge region of the LMC based on the IRSF/SIRIUS near-infrared survey
• Three-dimensional dust geometry of the LMC HI ridge region as revealed by the IRSF/SIRIUS survey