Targeting Bright Metal-poor Stars in the Disk and Halo Systems of the Galaxy

Autor(es)

Limberg, Guilherme ^[1] ; Santucci, Rafael M. ^{[2, 3]} ; Rossi, Silvia ^[1] ; Shank, Derek ^{[4, 5]} ; Placco, Vinicius M. ^[6] ; Beers, Timothy C. ^{[4, 5]} ; Schlaufman, Kevin C. ^[7] ; Casey, Andrew R. ^{[8, 9]} ; Perottoni, Helio D. ^[1] ; Lee, Young Sun ^[10]

Afiliação do(s) autor(es)

^[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 Planetario, BR-74055140 Goiania, Go - Brazil

^[4] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA

^[5] Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 - USA

^[6] NSFs NOIRLab, Community Sci & Data Ctr, 950 N Cherry Ave, Tucson, AZ 85719 - USA

^[7] Johns Hopkins Univ, Dept Phys & Astron, 3400 North Charles St, Baltimore, MD 21218 - USA

^[8] Monash Univ, Sch Phys & Astron, Wellington Rd, Clayton, Vic 3800 - Australia

^[9] ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Canberra, ACT 2611 - Australia

^[10] Chungnam Natl Univ, Dept Astron & Space Sci, Daejeon 34134 - South Korea

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 913, n. 1 MAY 2021.
• Citações Web of Science: 0

Resumo

We present the results of spectroscopic follow-up for 1897 low-metallicity star candidates, selected from the Best \& Brightest (B\&B) Survey, carried out with the GMOS-N/S (Gemini North/South telescopes) and Goodman (SOAR Telescope) spectrographs. From these low-resolution (R similar to 2000) spectra, we estimate stellar atmospheric parameters, as well as carbon and magnesium abundance ratios. We confirm that 56% of our program stars are metal-poor ({[}Fe/H] < - 1.0), 30% are very metal-poor (VMP; {[}Fe/H] < - 2.0), and 2% are extremely metal-poor (EMP; {[}Fe/H] < - 3.0). There are 191 carbon-enhanced metal-poor (CEMP) stars, resulting in CEMP fractions of 19% and 43% for the VMP and EMP regimes, respectively. A total of 94 confirmed CEMP stars belong to Group I (A(C) greater than or similar to 7.25) and 97 to Group II (A(C) less than or similar to 7.25) in the Yoon-Beers A(C)-{[}Fe/H] diagram. Moreover, we combine these data with Gaia EDR3 astrometric information to delineate new target-selection criteria, which have been applied to the Goodman/SOAR candidates, to more than double the efficiency for identification of bona fide VMP and EMP stars in comparison to random draws from the B\&B catalog. We demonstrate that this target-selection approach can achieve success rates of 96%, 76%, 28%, and 4% for {[}Fe/H] <= - 1.5, <= - 2.0, <= - 2.5 and <= - 3.0, respectively. Finally, we investigate the presence of dynamically interesting stars in our sample. We find that several VMP/EMP ({[}Fe/H] <= - 2.5) stars can be associated with either the disk system or halo substructures like Gaia-Sausage/Enceladus and Sequoia. (AU)

• Processo FAPESP: 14/18100-4 - Populações estelares na Via Láctea: bojo, halo, disco e regiões de formação de estrelas; instrumentação para espectroscopia de alta resolução
• Beneficiário: Beatriz Leonor Silveira Barbuy
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/50374-0 - Mosaic: the multi-object spectrograph for the ESO Extremely Large Telescope
• Beneficiário: Silvia Cristina Fernandes Rossi
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 18/21250-9 - Identificação de estrelas brilhantes pobres em metais a partir de fotometria Multi-Banda e acompanhamento espectroscópico
• Beneficiário: Hélio Dotto Perottoni
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado