Advanced search
Start date
Betweenand
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Abundance Patterns of alpha and Neutron-capture Elements in the Helmi Stream

Full text
Author(s):
Limberg, Guilherme [1] ; Santucci, Rafael M. [2, 3] ; Rossi, Silvia [1] ; Queiroz, Anna B. A. [4, 5] ; Chiappini, Cristina [4, 5] ; Souza, Stefano O. [1] ; Perottoni, Helio D. [1] ; Perez-Villegas, Angeles [6] ; Barbosa, Fabricia O. [1]
Total Authors: 9
Affiliation:
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Astron, BR-05508090 Sao Paulo, SP - Brazil
[2] Univ Fed Goias, Inst Fis, Campus Samambaia, BR-74001970 Goiania, Go - Brazil
[3] Univ Fed Goias, Inst Estudos Socioambientais, BR-74055140 Goiania, Go - Brazil
[4] Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam - Germany
[5] Lab Interinst E Astron LIneA, BR-20921400 Rio De Janeiro, RJ - Brazil
[6] Univ Nacl Autonoma Mexico, Inst Astron, Apartado Postal 106, Ensenada 22800, BC - Mexico
Total Affiliations: 6
Document type: Journal article
Source: Astrophysical Journal Letters; v. 913, n. 2 JUN 2021.
Web of Science Citations: 0
Abstract

We identified eight additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and Gaia EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with parameters determined from high-resolution spectroscopy and spanning a considerably wider (by similar to 0.5 dex) metallicity interval (- 2.5 less than or similar to {[}Fe/H] < - 1.0) than previously reported. Our study focuses on alpha (Mg and Ca) and neutron-capture (Ba and Eu) elements. We find that the chemistry of HStr is typical of dwarf spheroidal (dSph) galaxies, in good agreement with previous N-body simulations of this merging event. Stars of HStr constitute a clear declining sequence in {[}alpha/Fe] for increasing metallicity up to {[}Fe/H] similar to -1.0. Moreover, stars of HStr show a median value of +0.5 dex for {[}Eu/Fe] with a small dispersion (+/- 0.1 dex). Every star analyzed with {[}Fe/H] < -1.2 belongs to the r-process enhanced ({[}Eu/Fe] > +0.3 and {[}Ba/Eu] < 0.0) metal-poor category, providing remarkable evidence that, at such a low-metallicity regime, stars of HStr experienced enrichment in neutron-capture elements predominantly via r-process nucleosynthesis. Finally, the extended metallicity range also suggests an increase in {[}Ba/Eu] for higher {[}Fe/H], in conformity with other surviving dwarf satellite galaxies of the Milky Way. (AU)

FAPESP's process: 18/21250-9 - Identification of bright ultra-metal-poor stars from Multi-Band photometry and spectroscopic follow-up
Grantee:Hélio Dotto Perottoni
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 14/18100-4 - Stellar populations in the Milky Way: bulge, halo, disk and star forming regions; instrumentation for high resolution spectroscopy
Grantee:Beatriz Leonor Silveira Barbuy
Support type: Research Projects - Thematic Grants
FAPESP's process: 15/50374-0 - Mosaic: the multi-object spectrograph for the ESO Extremely Large Telescope
Grantee:Silvia Cristina Fernandes Rossi
Support type: Research Projects - Thematic Grants
FAPESP's process: 18/22044-3 - Bulge globular clusters: relics of the early formation of the galaxy
Grantee:Stefano Oliveira de Souza
Support type: Scholarships in Brazil - Doctorate (Direct)