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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 742383.0, MPI für Astronomie / Publikationen_mpia
Gemini/GRACES spectroscopy of stars in Tri II
Authors:Venn, K. A.; Starkenburg, E.; Malo, L.; Martin, N.; Laevens, B. P. M.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:Monthly Notices of the Royal Astronomical Society
Volume:466
Issue / Number:3
Start Page:3741
End Page:3752
Audience:Not Specified
Abstract / Description:The chemical abundance ratios and radial velocities for two stars in the recently discovered Triangulum II faint dwarf galaxy have been determined from high-resolution, medium signal-to-noise ratio spectra from the Gemini Remote Access to CFHT ESPaDonS Spectrograph facility. These stars have stellar parameters and metallicities similar to those derived from their photometry and medium-resolution Ca II triplet spectra, and supports that Triangulum II has a metallicity spread consistent with chemical evolution in a dwarf galaxy. The elemental abundances show that both stars have typical calcium abundances and barium upper limits for their metallicities, but low magnesium and sodium. This chemical composition resembles some stars in dwarf galaxies, attributed to inhomogeneous mixing in a low star formation environment, and/or yields from only a few supernova events. One of our targets (Star40) has an enhancement in potassium, and resembles some stars in the unusual outer halo star cluster, NGC 2419. Our other target (Star46) appears to be a binary based on a change in its radial velocity (Δvrad = 24.5 ±2.1 km s-1). This is consistent with variations found in binary stars in other dwarf galaxies. While this serves as a reminder of the high binary fraction in these ultrafaint dwarf galaxies, this particular object has had little impact on the previous determination of the velocity dispersion in Triangulum II.
Free Keywords:stars: abundances; galaxies: dwarf; galaxies: individual: Triangulum II
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stw3198
URL:http://adsabs.harvard.edu/abs/2017MNRAS.466.3741V
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