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Digging deeper into NGC 6868 I: Stellar population.
- Source :
- Monthly Notices of the Royal Astronomical Society; Jun2023, Vol. 522 Issue 2, p2570-2583, 14p
- Publication Year :
- 2023
-
Abstract
- We use Gemini integral field unit observations to map the stellar population properties in the inner region (∼680 × 470 pc<superscript>2</superscript>) of the galaxy NGC 6868. In order to understand the physical and chemical properties of the stellar content of this galaxy, we performed stellar population synthesis using the starlight code with the MILES simple stellar population models. We measured the absorption line indices Fe4383, Mg<subscript>2</subscript>, Mg<subscript>b</subscript>, Fe5270, and Fe5335 for the whole FoV, and used them to derive Fe3 and [MgFe]'. These indices were used to derive [α/Fe]. This galaxy is dominated by old metal-rich populations (12.6 Gyr; 1.0 and 1.6 Z<subscript>⊙</subscript>) with a negative metallicity gradient. We also found a recent (∼63 Myr) metal-rich (1.6 Z<subscript>⊙</subscript>) residual star formation in the centre of the galaxy. A dust lane with a peak extinction in the V band of 0.65 mag is seen. No signs of ordered stellar motion are found and the stellar kinematics is dispersion dominated. All indices show a spatial profile varying significantly along the FoV. Mg<subscript>2</subscript> shows a shallow gradient, compatible with the occurrence of mergers in the past. Mg<subscript>b</subscript> and Fe3 profiles suggest different enrichment processes for these elements. We observe three distinct regions: for R < 100 pc and R > 220 pc, Mg<subscript>2</subscript>, Mg<subscript>b</subscript> anticorrelate with respect to Fe3 and [MgFe]', and for 100 pc < R < 220 pc, they correlate, hinting at different enrichment histories. The [α/Fe] profile is really complex and has a central value of ∼0.2 dex. We interpret this as the result of a past merger with another galaxy with a different [α/Fe] history, thus explaining the [α/Fe] maps. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 522
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 163749092
- Full Text :
- https://doi.org/10.1093/mnras/stad1148