NOAO >   Observing Info >   Approved Programs >   2008B-0345

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Proposal Information for 2008B-0345


PI: Robin Ciardullo, Penn State University, rbc@astro.psu.edu
Address: Astronomy Department, 525 Davey Lab, University Park, PA 16802, USA

CoI: John Feldmeier, Youngstown State University
CoI: Chris Mihos, Case Western Reserve University
CoI: Kimberly Herrmann, Penn State University

Title: The Stellar Kinematics of Polar Ring Galaxies

Abstract: Polar ring galaxies (PRGs) are a unique resource for understanding the dark matter distribution of spiral galaxies. Because these systems contain two orthogonal orbital planes - one in the galactic disk and one perpendicular to that disk - an analysis of their kinematics should allow us to measure the shape of the galaxies' dark halo. Unfortunately, this is easier said than done. PRGs are lenticular galaxies, with little or no disk gas. To estimate major-axis rotation, one must either measure the kinematics of the systems' stars, or use indirect means (such as the Tully-Fisher relation). The former method is difficult, since absorption-line spectroscopy is only feasible in the galaxies' central regions, while the latter technique is subject to systematic errors. We propose to measure the stellar kinematics of two nearby polar ring galaxies by using planetary nebulae (PNe) as dynamical probes. Here, we propose to identify samples of ~ 100 PNe in the two well- known PRGs NGC 660 and NGC 2685 by performing on-band/off-band [O III] (lambda) 5007 and H(alpha) imaging with the OPTIC imager of WIYN\null. This will allow us to measure the systems' distances, search for low- surface brightness features associated with galactic mergers, and find targets for a follow-up radial velocity survey. If successful, we will re-apply next year to perform the PN spectroscopy and measure the flattening of the systems' dark haloes.


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