The internal proper motion kinematics of NGC346: past formation and future evolution

Abstract

We investigate the internal kinematics of the young star-forming region NGC 346 in the Small Magellanic Cloud. We used two epochs of deep F555W and F814W Hubble Space Telescope ACS observations with an 11-year baseline to determine proper motions, and study the kinematics of different populations, as identified by their color-magnitude diagram and spatial distribution characteristics. The proper motion field of the young stars shows a complex structure with spatially coherent patterns. NGC 346 upper-main sequence and pre-main sequence stars follow very similar motion patterns, with the outer parts of the cluster being characterized both by outflows and inflows. The proper motion field in the inner ~10 pc shows a combination of rotation and inflow, indicative of inspiraling motion. The rotation velocity in this regions peaks at ~3 km/s, whereas the inflow velocity peaks at ~1 km/s. Sub-clusters and massive young stellar objects in NGC 346 are found at the interface of significant changes in the coherence of the proper motion field. This suggests that turbulence is the main star formation driver in this region. The similar kinematics observed in the metal-poor NGC 346 and the Milky Way star-forming regions suggest that the differences in the cooling conditions due to the different amounts of metallicity and dust density between the SMC and our Galaxy are too small to alter significantly the process of star clusters assembly and growth. The main characteristics of our findings are consistent with various proposed star cluster formation models.

17 pages, 14 figures, Accpeted for publication on ApJ

References in corpus (25)

• The Gaia mission
• The MUSE second-generation VLT instrument
• The lifecycle of molecular clouds in nearby star-forming disc galaxies
• Is the SMC Bound to the LMC? The HST Proper Motion of the SMC
• Fast and inefficient star formation due to short-lived molecular clouds and rapid feedback
• The VLT-FLAMES Survey of Massive Stars: Observations centered on the Magellanic Cloud clusters NGC 330, NGC 346, NGC 2004, and the N11 region
• Equilibrium Star Cluster Formation
• On the Rapid Collapse and Evolution of Molecular Clouds
• Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. I. Sample Selection, Data Reduction and NGC 7078 Results
• The dynamics and outcome of star formation with jets, radiation, winds, and supernovae in concert
• Past and present star formation in the SMC: NGC 346 and its neighborhood
• N-body Models of Rotating Globular Clusters
• The Stellar Mass Distribution in the Giant Star Forming Region NGC 346
• The Discovery of a Population of Pre-Main Sequence Stars in N66/NGC346 from Deep HST/ACS Image
• The Spitzer Survey of the Small Magellanic Cloud: Discovery of Embedded Protostars in the HII Region NGC 346
• Rotation in young massive star clusters
• NGC 346 in the Small Magellanic Cloud. III. Recent Star Formation and Stellar Clustering Properties in the Bright HII Region N 66
• A census of massive stars in NGC 346. Stellar parameters and rotational velocities
• Comparative study between N-body and Fokker-Planck simulations for rotating star clusters: I. Equal-mass system
• First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion and Rotation
• An initial overview of the extent and structure of recent star formation within the Serpens Molecular Cloud using Gaia Data Release 2
• The Formation of a Stellar Association in the NGC 7000/IC 5070 Complex: Results from Kinematic Analysis of Stars and Gas
• A census of $\rho$ Oph candidate members from Gaia DR2
• Gaia Stellar Kinematics in the Head of the Orion A Cloud: Runaway Stellar Groups and Gravitational Infall
• ALMA reveals a cloud-cloud collision that triggers star formation in N66N of the Small Magellanic Cloud

Cited by in corpus (4)

• JWST-TST Proper Motions: I. High-Precision NIRISS Calibration and Large Magellanic Cloud Kinematics
• Protoplanetary discs around sun-like stars appear to live longer when the metallicity is low
• The Baryon Budget of Galaxies across the First Billion Years
• CO Observations of the SMC-N66 Hii Region with ALMA: Properties of Clumps along Filamentary Molecular Clouds and Possible Expansion Motion