The nature of Galactic bulges from SAURON absorption line strength maps

Reynier F. Peletier*, Jesús Falcón-Barroso, Katia Ganda, Roland Bacon, Michele Cappellari, Roger L. Davies, P. Tim De Zeeuw, Eric Emsellem, Davor Krajnović, Harald Kuntschner, Richard M. McDermid, Marc Sarzi, Glenn Van De Ven

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We discuss SAURON absorption line strength maps of a sample of 24 early-type spirals, mostly Sa. From the Lick indices H, Mgb and Fe 5015 we derive SSP-ages and metallicities. By comparing the scaling relations of Mg b and H and central velocity dispersion with the same relation for the edge-on sample of Falcn-Barroso et al. (2002) we derive a picture in which the central regions of Sa galaxies contain at least 2 components: one (or more) thin, disc-like component, often containing recent star formation, and another, elliptical-like component, consisting of old stars and rotating more slowly, dominating the light above the plane. If one defines a bulge to be the component responsible for the light in excess of the outer exponential disc, then many Sa-bulges are dominated by a thin, disc-like component containing recent star formation.

Original languageEnglish
Pages (from-to)485-488
Number of pages4
JournalProceedings of the International Astronomical Union
Issue numberS241
Publication statusPublished - Dec 2006
Externally publishedYes


  • Galaxies: bulges
  • Galaxies: spiral
  • Galaxies: stellar content


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