Scientific Seminars

The New Bulge - not the same as the old bulge

Roberto De Propris
University of Turku

2016-06-16    14:00    Brera - Aula corridoio strumenti

I present the latest results from our extensive study of the internal kinematics and metallicities of the stellar populations of the Galactic Bulge. We show that the Bulge does not actually consist of a pressure-supported system obeying the Fundamental Plane, but is instead a pure bar, in cylindrical rotation, formed by the buckling of a massive, early (thick?) disk. Our galaxy is therefore a bulgeless disk and has been so since z~3. We show that, however, there exists a population of RR Lyrae with hot kinematics in the inner 1kpc of the Galaxy; this may be part of the original nugget around which the Galaxy formed, although it is possible that this still belongs to the old Halo. We present the implications of this result for galaxy formation models where *all* Milky Way halos are expected to produce a classical bulge.