HS 2231+2441: an HW Vir system composed of a low-mass white dwarf and a brown dwarf

Autor(es)

Almeida, L. A. ^{[1, 2]} ; Damineli, A. ^[1] ; Rodrigues, C. V. ^[3] ; Pereira, M. G. ^[4] ; Jablonski, F. ^[3]

Afiliação do(s) autor(es)

^[1] Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Fed Rio Grande do Norte, UFRN, Dept Fis, CP 1641, BR-59072970 Natal, RN - Brazil

^[3] Inst Nacl Pesquisas Espaciais MCTIC, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[4] Univ Estadual Feira De Santana, Dept Fis, Av Transnordestina S-N, BR-44036900 Feira De Santana, BA - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 472, n. 3, p. 3093-3100, DEC 2017.
• Citações Web of Science: 3

Resumo

HW Vir systems are rare evolved eclipsing binaries composed of a hot compact star and a low-mass main sequence star in a close orbit. These systems provide a direct way to measure the fundamental properties, e.g. masses and radii, of their components, hence they are crucial in studying the formation of subdwarf B stars and low-mass white dwarfs, the common-envelope phase and the pre-phase of cataclysmic variables. Here, we present a detailed study of HS 2231+2441, an HW Vir type system, by analysing BVRCIC photometry and phase-resolved optical spectroscopy. The spectra of this system, which are dominated by the primary component features, were fitted using non-local thermodynamic equilibrium models providing an effective temperature T-eff = 28 500 +/- 500 K, surface gravity log g = 5.40 +/- 0.05 cm s(-2) and helium abundance log (n(He)/n(H)) = -2.52 +/- 0.07. The geometrical orbit and physical parameters were derived by simultaneously modelling the photometric and spectroscopic data using the Wilson-Devinney code. We derive two possible solutions for HS 2231+2441 that provide the component masses: M-1 = 0.19 M-circle dot and M-2 = 0.036 M-circle dot or M-1 = 0.288 M-circle dot and M-2 = 0.046 M-circle dot. Considering the possible evolutionary channels for forming a compact hot star, the primary of HS 2231+2441 probably evolved through the red-giant branch scenario and does not have a helium-burning core, which is consistent with a low-mass white dwarf. Both solutions are consistent with a brown dwarf as the secondary. (AU)

• Processo FAPESP: 12/09716-6 - Distâncias precisas de aglomerados jovens através de binárias eclipsantes massivas
• Beneficiário: Leonardo Andrade de Almeida
• Linha de fomento: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 11/51680-6 - Explorando o universo: da formação de galáxias aos planetas tipo-terra, com o Telescópio Gigante Magellan
• Beneficiário: João Evangelista Steiner
• Linha de fomento: Auxílio à Pesquisa - Projetos Especiais
• Processo FAPESP: 13/18245-0 - Soluções orbitais espectroscópicas completas para mais de 100 binárias massivas na região do "starburst" 30 Dourados
• Beneficiário: Leonardo Andrade de Almeida
• Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 13/26258-4 - Matéria superdensa no universo
• Beneficiário: Manuel Máximo Bastos Malheiro de Oliveira
• Linha de fomento: Auxílio à Pesquisa - Temático