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http://hdl.handle.net/20.500.12386/34384
Title: | Icarus: a flat and fast prograde stellar stream in the Milky Way disk | Authors: | RE FIORENTIN, Paola SPAGNA, Alessandro LATTANZI, Mario Gilberto Cignoni, Michele |
Issue Date: | 2021 | Journal: | THE ASTROPHYSICAL JOURNAL LETTERS | Number: | 907 | Issue: | 1 | First Page: | L16 | Abstract: | We explore the local volume of the Milky Way via chemical and kinematical measurements from high-quality astrometric and spectroscopic data recently released by the Gaia, APOGEE, and GALAH programs. We chemically select 1137 stars up to 2.5 kpc of the Sun and [Fe/H] ≤ -1.0 dex, and find evidence of statistically significant substructures. Clustering analysis in velocity space classifies 163 objects into eight kinematical groups, whose origin is further investigated with high-resolution N-body numerical simulations of single merging events. The two retrograde groups appear associated with Gaia-Sausage-Enceladus (GSE), while the slightly prograde group could be connected to GSE or possibly Wukong. We find evidence of a new 44-member-strong prograde stream that we name Icarus; to our knowledge, Icarus is the fast-rotating stream closest to the Galactic disk to date ( $\langle {Z}_{\max }\rangle \lesssim 0.5\,\mathrm{kpc}$ , ⟨V + V<SUB>LSR</SUB>⟩ ≃ 231 km s<SUP>-1</SUP>). Its peculiar chemical (⟨[Fe/H]⟩ ≃ -1.45, ⟨[Mg/Fe]⟩ ≃ -0.02) and dynamical (mean eccentricity ≃ 0.11) properties are consistent with the accretion of debris from a dwarf galaxy progenitor with a stellar mass of ∼10<SUP>9</SUP>M<SUB>⊙</SUB> on an initial prograde low-inclination orbit, ∼10°. The remaining prograde groups are either streams previously released by the same progenitor of Icarus (or Nyx), or remnants from different satellites accreted on initial orbits at higher inclination. | URI: | http://hdl.handle.net/20.500.12386/34384 | URL: | https://iopscience.iop.org/article/10.3847/2041-8213/abd53d | ISSN: | 2041-8205 | DOI: | 10.3847/2041-8213/abd53d | Bibcode ADS: | 2021ApJ...907L..16R | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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ReFiorentin_2021_ApJL_907_L16.pdf | PDF editoriale | 859.73 kB | Adobe PDF | View/Open |
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