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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 742640.0, MPI für Astronomie / Publikationen_mpia
Prolate rotation and metallicity gradient in the transforming dwarf galaxy Phoenix
Authors:Kacharov, N.; Battaglia, G.; Rejkuba, M.; Cole, A. A.; Carrera, R.; Fraternali, F.; Wilkinson, M. I.; Gallart, C. G.; Irwin, M.; Tolstoy, E.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:Monthly Notices of the Royal Astronomical Society
Volume:466
Issue / Number:2
Start Page:2006
End Page:2023
Audience:Not Specified
Abstract / Description: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 that 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 arcmin-1 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. A table containing the measured velocities, metallicities, and CaT equivalent widths of all spectroscopic targets is available online at the CDS.
Free Keywords:techniques: spectroscopic; galaxies: dwarf; galaxies: kinematics and dynamics; Local Group; galaxies: stellar content
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stw3188
URL:http://adsabs.harvard.edu/abs/2017MNRAS.466.2006K
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