638 research outputs found
The Formation of Galactic Bulges
We summarise some recent results about nearby galactic bulges that are
relevant to their formation. We highlight a number of significant advances in
our understanding of the surface brightness profiles, stellar populations, and
especially the very centers of spiral galaxies. We also view our own Milky Way
as if it were an external galaxy. Our main conclusions are that bulges of
early-type spirals (S0 -- Sb) contain central nuclear components, just like
late-type spirals and most other types of galaxies. The luminosities of these
central components correlate best with total bulge luminosity, and not as well
with morphological type. Bulges of early-type spiral galaxies follow the
fundamental plane and the colour/line strength vs. luminosity relations of
elliptical galaxies. Although we have a reasonable idea about bulges of
early-type spirals we know much less about late-type bulges. However, the close
resemblance of our Milky Way Bulge to bulges in external disk galaxies makes us
suspect that bulges of late-type spirals might be very similar as well.Comment: 10 pages, invited review presented at 'Baryons in Dark Matter',
Novigrad Oct 5-9, 2004; eds. R. Dettmar, U. Klein and P. Salucci. On-line
publication at http://pos.sissa.i
A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation Rings
We present near-infrared (H- and K-band) integral-field observations of the
circumnuclear star formation rings in five nearby spiral galaxies. The data,
obtained at the Very Large Telescope with the SINFONI spectrograph, are used to
construct maps of various emission lines that reveal the individual star
forming regions ("hot spots") delineating the rings. We derive the
morphological parameters of the rings, and construct velocity fields of the
stars and the emission line gas. We propose a qualitative, but robust,
diagnostic for relative hot spot ages based on the intensity ratios of the
emission lines Brackett gamma, HeI, and [FeII]. Application of this diagnostic
to the data presented here provides tentative support for a scenario in which
star formation in the rings is triggered predominantly at two well-defined
regions close to, and downstream from, the intersection of dust lanes along the
bar with the inner Lindblad resonance.Comment: 45 pages incl. 4 tables and 12 (mostly color) figures. Accepted for
publication in AJ. A version with full resolution figures can be obtained at
ftp://ftp.rssd.esa.int/pub/tboeker/SINFONI/ms.pd
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