Evidences of extragalactic origin and planet engulfment in the metal-poor twin pair HD 134439/HD 134440

Autor(es)

Reggiani, Henrique ^{[1, 2]} ; Melendez, Jorge ^[2]

Afiliação do(s) autor(es)

^[1] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg - Germany

^[2] Univ Sao Paulo, IAG, Inst Astron Geofis & Ciencias Atmosfer, Dept Astron, Rua Matao 1226, Cidade Univ, BR-05508900 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 475, n. 3, p. 3502-3510, APR 2018.
• Citações Web of Science: 3

Resumo

Recent studies of chemical abundances in metal-poor halo stars show the existence of different populations, which is important for studies of Galaxy formation and evolution. Here, we revisit the twin pair of chemically anomalous stars HD 134439 and HD 134440, using high resolution (R similar to 72 000) and high S/N ratio (S/N similar to 250) HDS/Subaru spectra. We compare them to the well-studied halo star HD 103095, using the line-by-line differential technique to estimate precise stellar parameters and LTE chemical abundances. We present the abundances of C, 0, Na, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Ba, La, Ce, Nd, and Sm. We compare our results to the precise abundance patterns of Nissen \& Schuster (2010) and data from dwarf Spheroidal galaxies (dSphs). We show that the abundance pattern of these stars appears to be closely linked to that of dSphs with {[}alpha/Fe] knee below {[}Fe/H] < -1.5. We also find a systematic difference of 0.06 +/- 0.01 dex between the abundances of these twin binary stars, which could be explained by the engulfment of a planet, thus suggesting that planet formation is possible at low metallicities ({[}Fe/H] = -1.4). (AU)

• Processo FAPESP: 12/24392-2 - Espectroscopia de alta precisão: impacto no estudo de planetas, estrelas, a galáxia e cosmologia
• Beneficiário: Jorge Luis Melendez Moreno
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• 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