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

Authors

  • A. de Lorenzo-Cáceres,

    Corresponding author
    1. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
    2. Depto. Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain
      E-mail: adlcr@iac.es (AdL-C); vazdekis@iac.es (AV); jalfonso@iac.es (JALA); enricomaria.corsini@unipd.it (EMC); vpdebattista@gmail.com (VPD)
    Search for more papers by this author
  • A. Vazdekis,

    Corresponding author
    1. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
    2. Depto. Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain
      E-mail: adlcr@iac.es (AdL-C); vazdekis@iac.es (AV); jalfonso@iac.es (JALA); enricomaria.corsini@unipd.it (EMC); vpdebattista@gmail.com (VPD)
    Search for more papers by this author
  • J. A. L. Aguerri,

    Corresponding author
    1. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
    2. Depto. Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain
      E-mail: adlcr@iac.es (AdL-C); vazdekis@iac.es (AV); jalfonso@iac.es (JALA); enricomaria.corsini@unipd.it (EMC); vpdebattista@gmail.com (VPD)
    Search for more papers by this author
  • E. M. Corsini,

    1. Dipartimento di Astronomia, Università di Padova, vicolo dell’Osservatorio 2, I-35122 Padova, Italy
    Search for more papers by this author
  • Victor P. Debattista

    Corresponding author
    1. Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE
      E-mail: adlcr@iac.es (AdL-C); vazdekis@iac.es (AV); jalfonso@iac.es (JALA); enricomaria.corsini@unipd.it (EMC); vpdebattista@gmail.com (VPD) RCUK Fellow.
    Search for more papers by this author

  • Based on observations carried out at the European Southern Observatory (ESO 70.B-0338).

E-mail: adlcr@iac.es (AdL-C); vazdekis@iac.es (AV); jalfonso@iac.es (JALA); enricomaria.corsini@unipd.it (EMC); vpdebattista@gmail.com (VPD)

RCUK Fellow.

ABSTRACT

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.

Ancillary