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|Title:||Prolate rotation and metallicity gradient in the transforming dwarf galaxy Phoenix|
Cole, A. A.
Wilkinson, Mark I.
Gallart, C. G.
|Publisher:||Oxford University Press (OUP), Royal Astronomical Society|
|Citation:||Monthly Notices of the Royal Astronomical Society, 2016|
|Abstract:||Transition type dwarf galaxies are thought to be systems undergoing the process of transformation from a star-forming into a passively evolving dwarf, which makes them particularly suitable to study evolutionary processes driving the existence of different dwarf morphological types. Here we present results from a spectroscopic survey of ∼200 individual red giant branch stars in the Phoenix dwarf, the closest transition type with a comparable luminosity to “classical” dwarf galaxies. We measure a systemic heliocentric velocity Vhelio = −21.2 ± 1.0 km s−1. Our survey reveals the clear presence of prolate rotation, which is aligned with the peculiar spatial distribution of the youngest stars in Phoenix. We speculate that both features might have arisen from the same event, possibly an accretion of a smaller system. The evolved stellar population of Phoenix is relatively metal-poor (<[Fe/H] > = − 1.49 ± 0.04 dex) and shows a large metallicity spread (σ[Fe/H] = 0.51 ± 0.04 dex), with a pronounced metallicity gradient of −0.13 ± 0.01 dex per arcmin similar to luminous, passive dwarf galaxies. We also report a discovery of an extremely metal-poor star candidate in Phoenix and discuss the importance of correcting for spatial sampling when interpreting the chemical properties of galaxies with metallicity gradients. This study presents a major leap forward in our knowledge of the internal kinematics of the Phoenix transition type dwarf galaxy, and the first wide area spectroscopic survey of its metallicity properties.|
|Rights:||Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: http://creativecommons.org/licenses/by-nc-nd/4.0/ Archived with reference to SHERPA/RoMEO and publisher website.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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|MNRAS-2016-Kacharov-mnras-stw3188.pdf||Post-review (final submitted author manuscript)||2.8 MB||Adobe PDF||View/Open|
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