Chemical Analysis of the Brightest Star of the Cetus II Ultrafaint Dwarf Galaxy Candidate*
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Published:2023-12-01
Issue:2
Volume:959
Page:141
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ISSN:0004-637X
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Container-title:The Astrophysical Journal
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language:
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Short-container-title:ApJ
Author:
Webber K. B.ORCID, Hansen T. T.ORCID, Marshall J. L., Simon J. D.ORCID, Pace A. B.ORCID, Mutlu-Pakdil B.ORCID, Drlica-Wagner A.ORCID, Martínez-Vázquez C. E.ORCID, Aguena M.ORCID, Allam S. S.ORCID, Alves O.ORCID, Bertin E.ORCID, Brooks D.ORCID, Carnero Rosell A.ORCID, Carretero J.ORCID, da Costa L. N.ORCID, De Vicente J.ORCID, Doel P., Ferrero I.ORCID, Friedel D.ORCID, Frieman J.ORCID, García-Bellido J.ORCID, Giannini G.ORCID, Gruen D.ORCID, Gruendl R. A.ORCID, Hinton S. R.ORCID, Hollowood D. L.ORCID, Honscheid K.ORCID, Kuehn K.ORCID, Mena-Fernández J.ORCID, Menanteau F.ORCID, Miquel R.ORCID, Ogando R. L. C.ORCID, Pereira M. E. S.ORCID, Pieres A.ORCID, Plazas Malagón A. A.ORCID, Sanchez E.ORCID, Santiago B., Smith J. AllynORCID, Smith M.ORCID, Suchyta E.ORCID, Tarle G.ORCID, To C.ORCID, Weaverdyck N.ORCID, Yanny B.ORCID
Abstract
Abstract
We present a detailed chemical abundance analysis of the brightest star in the ultrafaint dwarf (UFD) galaxy candidate Cetus II from high-resolution Magellan/MIKE spectra. For this star, DES J011740.53-173053, abundances or upper limits of 18 elements from carbon to europium are derived. Its chemical abundances generally follow those of other UFD galaxy stars, with a slight enhancement of the α-elements (Mg, Si, and Ca) and low neutron-capture element (Sr, Ba, and Eu) abundances supporting the classification of Cetus II as a likely UFD. The star exhibits lower Sc, Ti, and V abundances than Milky Way (MW) halo stars with similar metallicity. This signature is consistent with yields from a supernova originating from a star with a mass of ∼11.2 M
⊙. In addition, the star has a potassium abundance of [K/Fe] = 0.81, which is somewhat higher than the K abundances of MW halo stars with similar metallicity, a signature that is also present in a number of UFD galaxies. A comparison including globular clusters and stellar stream stars suggests that high K is a specific characteristic of some UFD galaxy stars and can thus be used to help classify objects as UFD galaxies.
Funder
National Science Foundation EC ∣ European Research Council
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
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