you are cordially invited to the Scientific Expert Meeting (SciExpMeet) that will be held at the Library of the Astronomical Observatory of Belgrade on Wednesday. 

Lecturer: Michal Bilek (LERMA, Observatoire de Paris AND Collège de France)

Title: Extragalactic archeology: the origin of the prominent tidal features in the galaxy NGC474

Abstract:

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NGC474 is a nearby lenticular galaxy famous for its dramatic system of tidal shells and streams. Such structures form in galaxy collisions. One of the shells and the galaxy itself were recently studied spectroscopically by two teams. We contributed to the investigations of this prominent object by applying the analytical shell identification method for estimating the time since the collision from the observed sizes of shells. We moreover run an N-body simulation that reproduced much of the morphology of the observed galaxy. This allowed us to built a detailed scenario of what has been happening in the galaxy in the last ~1 Gyr and how the tidal features formed. This includes the time since the merger, the geometry of the collision the explanation of the young stellar populations in the galaxy. The scenario accounts for all observational constraints. This work indicates that it is possible to reconstruct the formation shell galaxies in surprising detail by combining their deep images with the spectroscopy of their centers. Such data can now be routinely obtained.