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- Title
Kinematic and stellar population properties of the counter-rotating components in the S0 galaxy NGC 1366.
- Authors
Morelli, L.; Pizzella, A.; Coccato, L.; Corsini, E. M.; Bontà, E. Dalla; Buson, L. M.; Ivanov, V. D.; Pagotto, I.; Pompei, E.; Rocco, M.
- Abstract
Context. Many disk galaxies host two extended stellar components that rotate in opposite directions. The analysis of the stellar populations of the counter-rotating components provides constraints on the environmental and internal processes that drive their formation. Aims. The S0 NGC 1366 in the Fornax cluster is known to host a stellar component that is kinematically decoupled from the main body of the galaxy. Here we successfully separated the two counter-rotating stellar components to independently measure the kinematics and properties of their stellar populations. Methods. We performed a spectroscopic decomposition of the spectrum obtained along the galaxy major axis and separated the relative contribution of the two counter-rotating stellar components and of the ionized-gas component. We measured the line-strength indices of the two counter-rotating stellar components and modeled each of them with single stellar population models that account for the α/Fe overabundance. Results. We found that the counter-rotating stellar component is younger, has nearly the same metallicity, and is less α/Fe enhanced than the corotating component. Unlike most of the counter-rotating galaxies, the ionized gas detected in NGC 1366 is neither associated with the counter-rotating stellar component nor with the main galaxy body. On the contrary, it has a disordered distribution and a disturbed kinematics with multiple velocity components observed along the minor axis of the galaxy. Conclusions. The different properties of the counter-rotating stellar components and the kinematic peculiarities of the ionized gas suggest that NGC 1366 is at an intermediate stage of the acquisition process, building the counter-rotating components with some gas clouds still falling onto the galaxy.
- Subjects
DISK galaxies; STELLAR rotation; STELLAR populations; KINEMATICS; GALAXY spectra
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2017, Vol 600, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201630046