Mucciarelli, A.A.MucciarelliBELLAZZINI, MicheleMicheleBELLAZZINIIbata, R.R.IbataROMANO, DonatellaDonatellaROMANOChapman, S. C.S. C.ChapmanMonaco, L.L.Monaco2020-08-262020-08-2620170004-6361http://hdl.handle.net/20.500.12386/26848We present iron, magnesium, calcium, and titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9.0' ≃ 70 pc from the centre) from medium-resolution Keck/Deep Imaging Multi-Object Spectrograph spectra. All the considered stars belong to the massive globular cluster M 54 or to the central nucleus of the galaxy (Sgr, N). In particular we provide abundances for 109 stars with [Fe/H] ≥-1.0, more than doubling the available sample of spectroscopic metallicity and α-elements abundance estimates for Sgr dSph stars in this metallicity regime. We find for the first time a metallicity gradient in the Sgr, N population, whose peak iron abundance goes from [Fe/H] =-0.38 for R ≤ 2.5' to [Fe/H] =-0.57 for 5.0 <R ≤ 9.0'. On the other hand, the trends of [Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region explored by our study. We reproduce the observed chemical patterns of the Sagittarius dwarf spheroidal as a whole with a chemical evolution model which implies that a high mass progenitor (M<SUB>DM</SUB> = 6 × 10<SUP>10</SUP>M<SUB>☉</SUB>) and a significant event of mass-stripping occurred a few Gyr ago, presumably starting at the first peri-Galactic passage after infall. <P />Full Table 1 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A46">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A46</A>STAMPAenChemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxyArticle10.1051/0004-6361/2017307072-s2.0-85029166573000412231200047https://www.aanda.org/articles/aa/full_html/2017/09/aa30707-17/aa30707-17.html2017A&A...605A..46MFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation