[Previous] | [Session 52] | [Next]
P.R. Durrell (PSU), J.J. Feldmeier (CWRU), R. Ciardullo (PSU), G.H. Jacoby (WIYN), C. Mihos (CWRU)
The galaxy pair NGC 5194/95 (M51) is one of the closest and best known interacting systems. Despite its notoriety, however, many of its features are not well known. For example, extending westward from the companion NGC~5195 is a very low surface brightness tidal tail, which can only be seen in the deepest broadband exposures. This feature has not been well studied, either observationally or theoretically.
Our previous [O~III] \lambda 5007 survey of M51 (Feldmeier, Ciardullo, & Jacoby 1997) detected this tidal tail via the spatial distribution of planetary nebulae. This presents us with a unique opportunity to study a galaxy interaction in progress. To learn more about the NGC~5194/95 interaction we observed 35 planetary nebulae candidates spectroscopically using the WIYN telescope. Twenty-six of these planetaries are in western tidal tail, and another nine are south of the primary galaxy. We present the velocities of the planetary nebulae and outline their basic properties. Our velocity errors are less than 17 km/s, giving us enough resolution to constrain models of the interaction. We also present new self-consistent numerical models of the M51 system to interpret the observations.
The author(s) of this abstract have provided an email address for comments about the abstract: pdurrell@astro.psu.edu