000262426 001__ 262426
000262426 005__ 20190619220137.0
000262426 022__ $$a1432-0746
000262426 02470 $$a000448232900001$$2isi
000262426 0247_ $$a10.1051/0004-6361/201833414$$2doi
000262426 037__ $$aARTICLE
000262426 245__ $$aStellar chemo-kinematics of the Cetus dwarf spheroidal galaxy
000262426 260__ $$c2018$$aLes Ulis Cedex A$$bEDP SCIENCES S A
000262426 269__ $$a2018-10-25
000262426 336__ $$aJournal Articles
000262426 520__ $$aContext. The great majority of early-type dwarf galaxies, in the Local Group as well as in other galaxy groups, are found in the vicinity of much larger galaxies, making it hard to disentangle the role of internal versus external effects in driving their evolution.
000262426 520__ $$aAims. In order to minimize environmental effects and gain an insight into the internal mechanisms that shape the properties of these systems, we study one of the few dwarf spheroidal galaxies of the Local Group found in isolation: Cetus. This system is of particular interest since it does not follow the Local Group morphology-density relation.
000262426 520__ $$aMethods. We obtained Very Large Telescope (VLT) FORS2 spectra (R similar to 2600) in the region of the nIR CaII triplet lines for 80 candidate red giant branch (RGB) stars. The analysis yielded line-of-sight velocities and metallicities ([Fe/H]) for 54 bona fide member stars. Results. The kinematic analysis shows that Cetus is a mainly pressure-supported (sigma(v) = 11.0(-1.3)(+1.6) km s(-1)), dark-matter-dominated system (M-1/2/L-V = 23.9(-8.9)(+9.)7 M-circle dot/L-circle dot) with no significant signs of internal rotation. We find Cetus to be a metal-poor system with a significant metallicity spread (median [Fe/H] = -1.71 dex, median-absolute-deviation = 0.49 dex), as expected for its stellar mass. We report the presence of a mild metallicity gradient compatible with those found in other dwarf spheroidals of the same luminosity; we trace the presence of a stellar population gradient also in the spatial distribution of stars in different evolutionary phases in ancillary SuprimeCam photometric data. There are tentative indications of two chemo-kinematically distinct sub-populations, with the more metal-poor stars showing a hotter kinematics than the metal-richer ones. Furthermore, the photometric dataset reveals the presence of a foreground population that most likely belongs to the Sagittarius stream.
000262426 520__ $$aConclusions. This study represents an important step forward in assessing the internal kinematics of the Cetus dwarf spheroidal galaxy as well as the first wide-area spectroscopic determination of its metallicity properties. With our analysis, Cetus adds to the growing scatter in stellar-dark matter halo properties in low-mass galactic systems. The presence of a metallicity gradient akin to those found in similarly luminous and pressure-supported systems inhabiting very different environments may hint at metallicity gradients in Local Group early-type dwarfs being driven by internal mechanisms.
000262426 650__ $$aAstronomy & Astrophysics
000262426 650__ $$aAstronomy & Astrophysics
000262426 6531_ $$agalaxies: dwarf
000262426 6531_ $$alocal group
000262426 6531_ $$agalaxies: kinematics and dynamics
000262426 6531_ $$agalaxies: abundances
000262426 6531_ $$agalaxies: structure
000262426 6531_ $$atechniques: spectroscopic
000262426 6531_ $$astar-formation history
000262426 6531_ $$agiant branch stars
000262426 6531_ $$aca ii triplet
000262426 6531_ $$alocal group galaxies
000262426 6531_ $$amilky-way
000262426 6531_ $$asatellite galaxies
000262426 6531_ $$achemical evolution
000262426 6531_ $$aperiod variables
000262426 6531_ $$ahalo
000262426 6531_ $$asculptor
000262426 700__ $$aTaibi, S.
000262426 700__ $$aBattaglia, G.
000262426 700__ $$aKacharov, N.
000262426 700__ $$aRejkuba, M.
000262426 700__ $$aIrwin, M.
000262426 700__ $$aLeaman, R.
000262426 700__ $$aZoccali, M.
000262426 700__ $$aTolstoy, E.
000262426 700__ $$0245069$$aJablonka, P.$$g178340
000262426 773__ $$qA122$$j618$$tAstronomy & Astrophysics
000262426 8560_ $$fyves.revaz@epfl.ch
000262426 909C0 $$zPasquier, Simon$$0252365$$yApproved$$pLASTRO$$xU10933$$myves.revaz@epfl.ch
000262426 909CO $$particle$$ooai:infoscience.epfl.ch:262426$$pSB
000262426 961__ $$afantin.reichler@epfl.ch
000262426 973__ $$aEPFL$$sPUBLISHED$$rREVIEWED
000262426 980__ $$aARTICLE
000262426 980__ $$aWoS
000262426 981__ $$aoverwrite