The bar pattern speed of NGC 4431
Abstract
We present surface photometry and stellar kinematics of NGC 4431, a barred dwarf galaxy in the Virgo cluster undergoing a tidal interaction with one of its neighbors, NGC 4436. We measured its bar pattern speed using the Tremaine-Weinberg method, and derived the ratio of the corotation radius, DL, to the bar semi-major axis, aB. We found DL/aB=0.6+1.2-0.4 at 99% confidence level. Albeit with large uncertainty, the probability that the bar ends close to its corotation radius (i.e., 1.0 ≤ DL/aB ≤ 1.4) is about twice as likely as that the bar is much shorter than corotation radius (i.e., DL/aB > 1.4).
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