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Regrowth of stellar disks in mature galaxies: The two component nature of NGC 7217 revisited with VIRUS-W†⋄
Published online by Cambridge University Press: 09 February 2015
Abstract
We have obtained high spectral resolution (R ≈ 9000), integral field observations of the three spiral galaxies NGC 3521, NGC 7217 and NGC 7331 using the new fiber-based Integral Field Unit instrument VIRUS-W at the 2.7 m telescope of the McDonald Observatory in Texas. Our data allow us to revisit previous claims of counter rotation in these objects. A detailed kinematic decomposition of NGC 7217 shows that no counter rotating stellar component is present. We find that NGC 7217 hosts a low dispersion, rotating disk that is embedded in a high velocity dispersion stellar halo or bulge that is co-rotating with the disk. Due to the very different velocity dispersions (≈ 20 km s−1 vs. 150 km s−1) , we are further able to perform a Lick index analysis on both components separately which indicates that the two stellar populations are clearly separated in (Mgb,〈Fe〉) space. The velocities and dispersions of the faster component are very similar to those of the interstellar gas as measured from the [O iii] emission. Morphological evidence of active star formation in this component further suggests that NGC 7217 may be in the process of (re)growing a disk inside a more massive and higher dispersion stellar halo.
- Type
- Contributed Papers
- Information
- Proceedings of the International Astronomical Union , Volume 10 , Issue S309: Galaxies in 3D across the Universe , July 2014 , pp. 81 - 84
- Copyright
- Copyright © International Astronomical Union 2015
Footnotes
This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.
This paper contains data obtained at the Wendelstein Observatory of the Ludwig-Maximilians University Munich.