Magellanic Cloud Periphery Carbon Stars IV: The SMC

Abstract

The kinematics of 150 carbon stars observed at moderate dispersion on the periphery of the Small Magellanic Cloud are compared with the motions of neutral hydrogen and early type stars in the Inter-Cloud region. The distribution of radial velocities implies a configuration of these stars as a sheet inclined at 73+/-4 degrees to the plane of the sky. The near side, to the South, is dominated by a stellar component; to the North, the far side contains fewer carbon stars, and is dominated by the neutral gas. The upper velocity envelope of the stars is closely the same as that of the gas. This configuration is shown to be consistent with the known extension of the SMC along the line of sight, and is attributed to a tidally induced disruption of the SMC that originated in a close encounter with the LMC some 0.3 to 0.4 Gyr ago. The dearth of gas on the near side of the sheet is attributed to ablation processes akin to those inferred by Weiner & Williams (1996) to collisional excitation of the leading edges of Magellanic Stream clouds. Comparison with pre LMC/SMC encounter kinematic data of Hardy, Suntzeff, & Azzopardi (1989) of carbon stars, with data of stars formed after the encounter, of Maurice et al. (1989), and Mathewson et al. (a986, 1988) leaves little doubt that forces other than gravity play a role in the dynamics of the H I.

30 pages; 7 figures, latex compiled, 1 table; to appear in AJ (June 2000)

References in corpus (2)

• Ca II Triplet Spectroscopy of Giants in SMC Star Clusters: Abundances, Velocities and the Age-Metallicity Relation
• Young Star Clusters in the Dwarf Irregular Galaxy, UGC 7636, Interacting with the Giant Elliptical Galaxy NGC 4472

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• Long Period Variables in the Magellanic Clouds: OGLE + 2MASS + DENIS
• Kinematics of massive stars in the Small Magellanic Cloud
• Discovery of a Large Stellar Periphery Around the Small Magellanic Cloud
• Interpretation of the Spatial Power Spectra of Neutral Hydrogen in the Galaxy and in the Small Magellanic Cloud
• The MAGellanic Inter-Cloud project (MAGIC) I: Evidence for intermediate-age stellar populations in between the Magellanic Clouds
• Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables
• A Local Group Polar Ring Galaxy: NGC 6822
• Constraining the Mass Profiles of Stellar Systems: Schwarzschild Modeling of Discrete Velocity Datasets
• Stellar Populations in the Outskirts of the Small Magellanic Cloud: No Outer Edge Yet
• The VMC Survey -- XL. Three-dimensional structure of the Small Magellanic Cloud as derived from red clump stars
• Morphology and metallicity of the Small Magellanic Cloud using RRab stars
• A Radial Velocity and Calcium Triplet abundance survey of field Small Magellanic Cloud giants
• Star-burst regions in the LMC
• Kinematics of stellar substructures in the Small Magellanic Cloud