The diversity of thick galactic discs
Abstract
Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on S0-a disc galaxies located in different environments: NGC 4111 in a dense group, NGC 4710 in the Virgo cluster, and NGC 5422 in a sparse group. We see intermediate age (4-5 Gyr) metal rich ([Fe/H] ∼- 0.2…0.0 dex) stellar populations in NGC 4111 and NGC 4710. On the other hand, NGC 5422 does not harbour young stars, its disc is thick and old (10 Gyr), without evidence for a second component, and its α-element abundance suggests a 1.5-2 Gyr long formation epoch implying its formation at high redshift. Our results suggest the diversity of thick disc formation scenarios.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 2016
- DOI:
- 10.1093/mnrasl/slw083
- arXiv:
- arXiv:1604.07624
- Bibcode:
- 2016MNRAS.460L..89K
- Keywords:
-
- galaxies: evolution;
- galaxies: stellar content;
- galaxies: structure;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Accepted for publication in MNRAS Letters, 6 pages, 3 figures, 1 table