EPJ Web of Conferences
Volume 19, 2012Assembling the Puzzle of the Milky Way
|Number of page(s)||5|
|Section||Inner Galaxy: Bulge/Bar/Inner Disc Interplay, Role of Mergers|
|Published online||07 February 2012|
The formation of the Galactic bulge of the Milky Way
Research School of Astronomy & Astrophysics, The Australian National University
a e-mail: firstname.lastname@example.org
We aim to determine if the bulge formed via mergers as predicted by Cold Dark Matter (CDM) theory, or from disk instabilities, as suggested by its boxy shape, or both processes. We are observing about 28,000 bulge stars in fields that span longitudes of − 31 to + 26° and latitudes of − 5° to − 10°, targeting mostly red clump giants and we are measuring stellar velocities and chemical abundances. We have almost concluded our observations and have analysed data of 23,000 stars. We find a cylindrical rotation profile for the bulge which blends smoothly out into the disk and from the [Fe/H] results we find the bulge to be comprised of separate components, with an underlying slowly rotating metal poor subsample which we believe to be the inner halo stars and metal weak thick disk. We find only a small [Fe/H] gradient with latitude in the bulge, of − 0.07dex/kpc. This weak gradient does not necessarily support a merger origin for our bulge and the composite nature of the bulge is consistent with formation out of the thin disk as per instability formation models.
© Owned by the authors, published by EDP Sciences, 2012
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