Publication: Carbon and nitrogen abundances in early-type galaxies
Loading...
Official URL
Full text at PDC
Publication Date
2009-02-01
Authors
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
Citations
Exportar
Abstract
For the first time, we undertake a systematic examination of the nitrogen abundances using the NH3360 feature for a sample of 35 early-type galaxies spanning a range of masses and local environment. The nitrogen-sensitive molecular feature at 3360Å has been employed in conjunction with a suite of atomic- and molecular-sensitive indices to provide unique and definitive constraints on the chemical content of these systems. By employing NH3360, we are now able to break the carbon, nitrogen, and oxygen degeneracies inherent to the use of the cyanogen (CN) index. We demonstrate that the NH3360 feature shows little dependency upon the velocity dispersion (our proxy for mass) of the galaxies, contrary to what is seen for carbon-and magnesium-sensitive indices. At face value, these results are at odds with conclusions drawn previously using indices sensitive to both carbon and nitrogen, such as CN. With the aid of stellar population models, we find that the N/Fe ratios in these galaxies are consistent with being mildly enhanced with respect to the solar ratio. We also explore the dependence of these findings upon environment, by analyzing the co-added spectra of galaxies in the field and the Coma cluster. We confirm the previously found differences in carbon abundances between galaxies in low-and high-density environments, while showing that these differences do not seem to exist for nitrogen. We discuss the implications of these findings for the derivation of the star-formation histories in early-type galaxies, and for the origin of carbon and nitrogen themselves.
Description
© 2009. The American Astronomical Society. All rights reserved.
We thank Francesca Matteucci and Reynier Peletier for several very useful discussions. The expert guidance of the referee, Judy Cohen, is gratefully acknowledged. This work has been partially supported by the Spanish research project AYA2007-67752-C03-03, the Marie Curie Intra-European Fellowship scheme within the 6th European Community Framework Programme (PSB), UK's Science & Technology Facilities Council (BKG). E. T. acknowledges the support of the University of Central Lancashire's Livesey Award scheme (PSB).
UCM subjects
Unesco subjects
Keywords
Citation
Ballero, S. K., Matteucci, F., Origlia, L., & Rich, R. M. 2007, A&A, 467, 123
Bessell, M. S., & Norris, J. 1982, ApJ, 263, L29
Boulade, O., Rose, J. A., & Vigroux, L. 1988, AJ, 96, 1319
Bruzual, G., & Charlot, S. 2003, MNRAS, 344, 1000
Burstein, D. 2003, in ASP Conf. Ser. 297, Star Formation Through Time, ed. E. Pérez, R. M. González Delgado, & G. Tenorio Tagle (San Francisco, CA: ASP), 253
Burstein, D., Faber, S. M., Gaskell, C. M., & Krumm, N. 1984, ApJ, 287, 586
Cardiel, N. 1999, PhD thesis, Univ. Complutense de Madrid, Spain
Carigi, L., Peimbert, M., Esteban, C., & García Rojas, J. 2005, ApJ, 623, 213
Chiappini, C., et al. 2006, A&A, 449, L27
Chiappini, C., Romano, D., & Matteucci, F. 2003, MNRAS, 339, 63
Clemens, M. S., et al. 2006, MNRAS, 370, 702
Davidge, T. J., & Clark, C. C. 1994, AJ, 107, 946
Fenner, Y., et al. 2003, PASA, 20, 340
Graves, G. J., & Schiavon, R. P. 2008, ApJS, 177, 446
Hughes, G. L., Gibson, B. K., Carigi, L., Sánchez Blázquez, P., Chávez, J. M., & Lambert, D. L. 2008, MNRAS, 390, 1710
Kelson, D. D., Illingworth, G. D., Franx, M., & van Dokkum, P. G. 2006, ApJ, 653, 159
Kodama, T., & Arimoto, N. 1998, MNRAS, 300, 193
Matteucci, F. 1986, MNRAS, 221, 911
Meynet, G., & Maeder, A. 2002, A&A, 390, 561
Norris, J. E., Ryan, S. G., Beers, T. C., Aoki, W., & Ando, H. 2002, ApJ, 569, L107
O’Connell, R. W. 1976, ApJ, 206, 370
Ponder, J. M., et al. 1998, AJ, 116, 2297
Renzini, A., & Voli, M. 1981, A&A, 94, 175
Sánchez Blázquez, P., Gorgas, J., Cardiel, N., Cenarro, J., & González, J. J. 2003, ApJ, 590, L91
Sánchez Blázquez, P., Gorgas, J., Cardiel, N., & González, J. J. 2006, A&A, 457, 787
Schiavon, R. P. 2007, ApJS, 171, 146
Serven, J., Worthey, G., & Briley, M. M. 2005, ApJ, 627, 754
Sneden, C. 1973, ApJ, 184, 839
Tomkin, J., & Lambert, D. L. 1984, ApJ, 279, 220
Worthey, G. 1994, ApJS, 95, 107
Worthey, G. 1998, PASP, 110, 888