GMOS spectroscopy of the S0 galaxy NGC 3115 |
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| Authors: | Mark A Norris Ray M Sharples Harald Kuntschner |
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| Institution: | Department of Physics, Science Laboratories, South Road, Durham;Space Telescope European Coordinating Facility, European Southern Observatory, Karl-Schwarzchild-Str. 2, 85748 Garching, Germany |
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| Abstract: | We present Gemini Multi-Object Spectrograph longslit spectroscopy of the isolated S0 galaxy NGC 3115. We have determined kinematical data and Lick/IDS absorption line-strength indices for the major axis out to around 9 kpc and for the minor axis out to around 5 kpc (around 2R e ). Using stellar population models which include the effects of variable α/Fe] ratios, we derive metallicities, abundance ratios and ages for the stellar population of NGC 3115. We find that α/Fe] remains fairly constant with increasing radius at around α/Fe]= 0.17 for the major axis but increases rapidly for the minor axis to around α/Fe]= 0.3 . We also find that to first order, this behaviour can be explained by a simple spheroid + disc model, where the spheroid has α/Fe]= 0.3 and the disc shows close to solar abundance ratios. The disc also appears considerably younger than the spheroid, having an age of around 6 Gyr compared to 12 Gyr for the spheroid. We compare these results to those previously presented for the globular cluster system of NGC 3115. |
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| Keywords: | galaxies: abundances galaxies: general globular clusters: general galaxies: stellar content galaxies: individual: NGC 3115 |
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