Open AccessGMOS spectroscopy of the S0 galaxy NGC 3115
Author(s) -
Norris Mark A.,
Sharples Ray M.,
Kuntschner Harald
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09992.x
Subject(s) - physics , astrophysics , globular cluster , galaxy , stellar population , spheroid , radius , population , spectroscopy , astronomy , star formation , chemistry , computer security , demography , sociology , computer science , in vitro , biochemistry
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.