1. Abundance ratios and IMF slopes in the dwarf elliptical galaxy NGC 1396 with MUSE
- Author
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F. La Barbera, Roberto Munoz, S. I. Loubser, Michael Hilker, Maurizio Paolillo, Thorsten Lisker, Jesús Falcón-Barroso, Nicola R. Napolitano, G. van de Ven, Rory Smith, Thomas H. Puzia, Mariya Lyubenova, J. J. Mentz, Mark A. Norris, Ruben Sanchez-Janssen, Michele Cantiello, Michael A. Beasley, Reynier Peletier, Massimo Capaccioli, Mentz, J. J., La Barbera, F., Peletier, R. F., Falcón Barroso, J., Lisker, T., van de Ven, G., Loubser, S. I., Hilker, M., Sánchez Janssen, R., Napolitano, N., Cantiello, M., Capaccioli, Massimo, Norris, M., Paolillo, Maurizio, Smith, R., Beasley, M. A., Lyubenova, M., Munoz, R., Puzia, T., and Astronomy
- Subjects
CAII TRIPLET ABSORPTION ,METALLICITY GRADIENTS ,Initial mass function ,INITIAL MASS FUNCTION ,F540 ,FOS: Physical sciences ,F500 ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Hubble sequence ,VIRGO-CLUSTER ,symbols.namesake ,galaxies: abundance ,galaxies: individual: (NGC 1396) ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Interacting galaxy ,Dwarf elliptical galaxy ,Fornax Cluster ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Dwarf galaxy ,STAR-FORMATION HISTORIES ,Physics ,010308 nuclear & particles physics ,F510 ,GALACTIC CHEMICAL EVOLUTION ,Astronomy ,Astronomy and Astrophysics ,galaxies: dwarf ,Astrophysics - Astrophysics of Galaxies ,Dwarf spheroidal galaxy ,Space and Planetary Science ,STELLAR POPULATION SYNTHESIS ,Globular cluster ,Astrophysics of Galaxies (astro-ph.GA) ,symbols ,galaxies: stellar content ,DIGITAL SKY SURVEY ,galaxies: abundances ,Astrophysics::Earth and Planetary Astrophysics ,ACS FORNAX CLUSTER ,galaxies: evolution ,M31 GLOBULAR-CLUSTERS - Abstract
Deep observations of the dwarf elliptical (dE) galaxy NGC 1396 (M$_V = -16.60$, Mass $\sim 4\times10^8$ M$_\odot$), located in the Fornax cluster, have been performed with the VLT/ MUSE spectrograph in the wavelength region from $4750-9350$ \AA{}. In this paper we present a stellar population analysis studying chemical abundances, the star formation history (SFH) and the stellar initial mass function (IMF) as a function of galacto-centric distance. Different, independent ways to analyse the stellar populations result in a luminosity-weighted age of $\sim$ 6 Gyr and a metallicity [Fe/H]$\sim$ $-0.4$, similar to other dEs of similar mass. We find unusually overabundant values of [Ca/Fe] $\sim +0.1$, and under-abundant Sodium, with [Na/Fe] values around $-0.1$, while [Mg/Fe] is overabundant at all radii, increasing from $\sim+0.1$ in the centre to $\sim +0.2$ dex. We notice a significant metallicity and age gradient within this dwarf galaxy. To constrain the stellar IMF of NGC 1396, we find that the IMF of NGC 1396 is consistent with either a Kroupa-like or a top-heavy distribution, while a bottom-heavy IMF is firmly ruled out. An analysis of the abundance ratios, and a comparison with galaxies in the Local Group, shows that the chemical enrichment history of NGC 1396 is similar to the Galactic disc, with an extended star formation history. This would be the case if the galaxy originated from a LMC-sized dwarf galaxy progenitor, which would lose its gas while falling into the Fornax cluster., Comment: 21 pages, 17 figures
- Published
- 2016