Autor(es)

Limberg, Guilherme ; Queiroz, Anna B. A. ; Perottoni, Helio D. ; Rossi, Silvia ; Amarante, Joao A. S. ; Santucci, Rafael M. ; Chiappini, Cristina ; Perez-Villegas, Angeles ; Lee, Young Sun

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 946, n. 2, p. 15-pg., 2023-04-01.

Resumo

In this work, we study the phase-space and chemical properties of the Sagittarius (Sgr) stream, the tidal tails produced by the ongoing destruction of the Sgr dwarf spheroidal (dSph) galaxy, focusing on its very metal-poor (VMP; [Fe/H] < -2) content. We combine spectroscopic and astrometric information from SEGUE and Gaia EDR3, respectively, with data products from a new large-scale run of the StarHorse spectrophotometric code. Our selection criteria yield similar to 1600 stream members, including >200 VMP stars. We find the leading arm (b > 0 degrees) of the Sgr stream to be more metal-poor, by similar to 0.2 dex, than the trailing one (b < 0 degrees). With a subsample of turnoff and subgiant stars, we estimate this substructure's stellar population to be similar to 1 Gyr older than the thick disk's. With the aid of an N-body model of the Sgr system, we verify that simulated particles stripped earlier (>2 Gyr ago) have present-day phase-space properties similar to lower metallicity stream stars. Conversely, those stripped more recently (<2 Gyr) are preferentially akin to metal-rich ([Fe/H] > -1) members of the stream. Such correlation between kinematics and chemistry can be explained by the existence of a dynamically hotter, less centrally concentrated, and more metal-poor population in Sgr dSph prior to its disruption, implying that this galaxy was able to develop a metallicity gradient before its accretion. Finally, we identified several carbon-enhanced metal-poor ([C/Fe] > +0.7 and [Fe/H] <= -1.5) stars in the Sgr stream, which might be in tension with current observations of its remaining core where such objects are not found. (AU)

• Processo FAPESP: 22/04079-0 - Caracterizando galáxias anãs ultra-fracas com o levantamento S-PLUS
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• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
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• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 15/50374-0 - Mosaic: the multi-object spectrograph for the ESO Extremely Large Telescope
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• Modalidade de apoio: Auxílio à Pesquisa - Temático
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• Beneficiário: Beatriz Leonor Silveira Barbuy
• Modalidade de apoio: Auxílio à Pesquisa - Temático
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• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
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• Beneficiário: Guilherme Limberg
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado Direto