NOAO >   Observing Info >   Approved Programs >   2009A-0086

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Proposal Information for 2009A-0086


PI: Roger Lynds, NOAO, rlynds@noao.edu
Address: P.O. Box 26732, 950 N. Cherry Ave, Tucson, Arizona 85726, United States

CoI: Earl O'Neil, Raytheon

Title: Precursors to Galaxy Merging

Abstract: NGC 6745 and two minor satellite galaxies comprise a physical system in which the companions have penetrated the material volume of the larger galaxy. When the non-stellar material in two galaxies meet at differential velocities much greater than the speed of sound, shock waves in the combined medium are produced which, in turn, tend to foster new star formation. Because the stars and clusters that are produced will kinematically reflect on average the momentum balance of the material from which they are made, the whole assemblage of new stars will be kinematically distinct from either of the galaxies involved in the encounter and will in fact become a new galaxy in its own distinct orbit. In the case of NGC 6745, one of these star-forming encounters is currently in progress, and we will not have the opportunity to observe the gravitation integrity of the resulting system of new stars. However, there is evidence in the case of a second companion galaxy that such a star-forming encounter occurred long ago. We think we have detected the stars that were produced in that encounter, but that detection is at the limit of existing observational material. We therefore ask for telescope time to obtain especially deep imaging so as to assess the dispersal of the stars along the common orbit.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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