EVIDENCE OF A MISALIGNED SECONDARY BAR IN THE LARGE MAGELLANIC CLOUD

摘要

Evidence of a misaligned secondary bar, within the primary bar of the Large Magellanic Cloud (LMC), is presented. The density distribution and the dereddened mean magnitudes (I_0) of the red clump stars in the bar obtained from the Optical Gravitational Lensing Experiment Ⅱ data are used for this study. The bar region that predominantly showed a wavy pattern in the line of sight in a recent paper by Subramaniam was located. These points in the X-Z plane delineate an S-shaped pattern, clearly indicating a misaligned bar. This feature is statistically significant and does not depend on the considered value of I_0 for the LMC center. The rest of the bar region was not found to show the warp or the wavy pattern. The secondary bar is found to be considerably elongated in the Z-direction, with an inclination of 66.5° +- 0.9°, whereas the undisturbed part of the primary bar is found to have an inclination of 15.1° +- 2.7°, such that the eastern sides are closer to us with respect to the western sides of both the bars. The P.A._(maj) of the secondary bar is found to be 108.4° +- 7.3°. The streaming motions found in the H Ⅰ velocity map close to the LMC center could be caused by the secondary bar. The recent star formation and the gas distribution in LMC could be driven by the misaligned secondary bar.