Bibcode
Tolstoy, Eline; Skúladóttir, Ása; Battaglia, Giuseppina; Brown, Anthony G. A.; Massari, Davide; Irwin, Michael J.; Starkenburg, Else; Salvadori, Stefania; Hill, Vanessa; Jablonka, Pascale; Salaris, Maurizio; van Essen, Thom; Olsthoorn, Carla; Helmi, Amina; Pritchard, John
Bibliographical reference
Astronomy and Astrophysics
Advertised on:
7
2023
Journal
Citations
9
Refereed citations
8
Description
We present a new homogeneous survey of VLT/FLAMES LR8 line-of-sight radial velocities (vlos) for 1604 resolved red giant branch stars in the Sculptor dwarf spheroidal galaxy. In addition, we provide reliable Ca II triplet metallicities, [Fe/H], for 1339 of these stars. From this combination of new observations (2257 individual spectra) with ESO archival data (2389 spectra), we obtain the largest and most complete sample of vlos and [Fe/H] measurements for individual stars in any dwarf galaxy. Our sample includes VLT/FLAMES LR8 spectra for ∼55% of the red giant branch stars at G < 20 from Gaia DR3, and > 70% of the brightest stars, G < 18.75. Our spectroscopic velocities are combined with Gaia DR3 proper motions and parallax measurements for a new and more precise membership analysis. We look again at the global characteristics of Sculptor, deriving a mean metallicity of ⟨[Fe/H]⟩ = −1.82 ± 0.45 and a mean line-of-sight velocity of ⟨vlos⟩ = + 111.2 ± 0.25 km s−1. There is a clear metallicity gradient in Sculptor, −0.7deg dex−1, with the most metal-rich population being the most centrally concentrated. Furthermore, the most metal-poor population in Sculptor, [Fe/H]< − 2.5, appears to show kinematic properties distinct from the rest of the stellar population. Finally, we combine our results with the exquisite Gaia DR3 multi-colour photometry to further investigate the colour-magnitude diagram of the resolved stellar population in Sculptor. Our detailed analysis shows a similar global picture as previous studies, but with much more precise detail, revealing that Sculptor has more complex properties than previously thought. This survey emphasises the role of the stellar spectroscopy technique and this galaxy as a benchmark system for modelling galaxy formation and evolution on small scales. Full Tables E.1 and E.2 are only available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/675/A49 Based on VLT/FLAMES observations collected at the European Organisation for Astronomical Research (ESO) in the Southern Hemisphere under programmes 171.B-0588, 072.D-0245, 076.B-0391, 079.B-0435, 593.D-0309, 098.D-0160, 0100.B-0337, 0101.D-0210, 0101.B-0189, and 0102.B-0786.
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![A laser beam launched from the VLT's Yepun telescope and in background a majestic view of the southern sky, with the disc of the Milky Way crossing the image and the Magellanic Clouds on the top right A view of our Milky Way galaxy with its close neighbors the Magellanic Clouds](/sites/default/files/styles/crop_square_2_2_to_320px/public/images/project/imagen-battaglia.jpg?h=fc948ffc&itok=zzZBOpLu)
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli