Tuesday 30 November at 2:30pm at Gemini HQ Seminar Room (note location)

Linda Sparke - Univ. Wisconsin

"Multiply Barred and Lopsided Galaxies"

ABSTRACT: "High-resolution optical and near-infrared images of the centers of barred galaxies have revealed smaller, secondary bars within the main bar. A recent survey with the WIYN telescope shows that these are quite common: we find them in about 30% of our barred S0 and Sa systems. The inner bar appears randomly oriented with respect to the main outer bar, suggesting that the two rotate independently. I will discuss how one can search for regular orbits in such a periodically-changing gravitational potential, and how stars following stable orbits could support the inner bar. An additional complication of disk galaxies is that the outer parts are often lopsided. I will present a dynamical model for lopsidedness, and show how it can explain the asymmetric character of the gas velocity fields measured in real systems."