Constraining the formation of inner bars: photometry, kinematics and stellar populations in NGC 357

de Lorenzo-Cáceres, A.; Vazdekis, A.; Aguerri, J. A. L.; Corsini, E. M.; Debattista, Victor P.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 420, Issue 2, pp. 1092-1106.

Advertised on:
2
2012
Number of authors
5
IAC number of authors
3
Citations
36
Refereed citations
35
Description
Double-barred galaxies are common in the local Universe, with approximately one-third of barred spirals hosting a smaller, inner bar. Nested bars have been proposed as a mechanism to transport gas to the very central regions of the galaxy, trigger star formation and contribute to the growth of the bulge. To test this idea, we perform for the first time a detailed analysis of the photometry, kinematics and stellar populations of a double-barred galaxy: NGC 357. We find that this galaxy is either hosting a pseudo-bulge or a classical bulge together with an inner disc. We compare the relative mean luminosity-weighted age, metallicity and α-enhancement between the (pseudo-)bulge, inner bar and outer bar, finding that the three structures are nearly coeval and old. Moreover, the bulge and inner bar present the same metallicity and overabundance, whereas the outer bar tends to be less metal rich and more α-enhanced. These results point out that, rather than the classical secular scenario in which gas and star formation play a major role, the redistribution of the existing stars is driving the formation of the inner structures. Based on observations carried out at the European Southern Observatory (ESO 70.B-0338).
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Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro