IAU Symposium Abstract S186-077P


Ocular Galaxies: NGC~2535 and its Starburst Companion NGC~2536


E. Brinks1, M. Kaufman2, D.M. Elmegreen3, M. Thomasson4, B.G. Elmegreen5, C. Struck6, M. Klari'c7
1 Univ. Guanajuato, Mexico < ebrinks@andromeda.cimat.mx >
2 Ohio State University, USA < rallis@mps.ohio-state.edu >
3 Vassar College Observatory, USA < elmegreen@vassar.edu >
4 Onsala Space Observatory, Sweden < magnus@oso.chalmers.se >
5 T.J.~Watson Research Center, USA < bge@watson.ibm.com >
6 Iowa State University, USA < curt@iastate.edu >
7 Midlands Techn. College, USA < klaricm@mtc2.mid.tec.sc.us >



We present HI, CO and optical observations of the ocular galaxy NGC 2535 and its starburst companion NGC 2536. NGC 2535 has an ocular (eye-shaped) structure with two long tidal arms. Such morphologies are indicative of a very recent, close, non-merging encounter. They have been reproduced in numerical models when the orbit of the companion is prograde and nearly in-plane. Because the ocular feature is short-lived, it restricts the numerical models and allows the determination of a unique solution to the orbit of the interacting galaxies. We will show that the ocular shape of the disk of NGC 2535 is intrinsically oval and that the velocity anomalies found in HI and in earlier H$\alpha$ Fabry-Perot maps can be entirely explained by the interaction. Moreover, the disk gas shows high velocity dispersion throughout. We find five unusually massive HI clouds without any obvious stellar counterpart. We will compare these results with our published work on another ocular galaxy, IC 2163, which is interacting with NGC 2077.