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

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

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Almeida, L. A. [1, 2] ; Damineli, A. [1] ; Rodrigues, C. V. [3] ; Pereira, M. G. [4] ; Jablonski, F. [3]
Total Authors: 5
[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
Total Affiliations: 4
Document type: Journal article
Source: Monthly Notices of the Royal Astronomical Society; v. 472, n. 3, p. 3093-3100, DEC 2017.
Web of Science Citations: 3

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)

FAPESP's process: 13/26258-4 - Superdense matter in the universe
Grantee:Manuel Máximo Bastos Malheiro de Oliveira
Support type: Research Projects - Thematic Grants
FAPESP's process: 13/18245-0 - Full spectroscopic orbital solutions for more than 100 massive binaries in the high-mass starburst region 30 Doradus
Grantee:Leonardo Andrade de Almeida
Support type: Scholarships abroad - Research Internship - Post-doctor
FAPESP's process: 12/09716-6 - Accurate distances to young clusters through massive eclipsing binaries
Grantee:Leonardo Andrade de Almeida
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 11/51680-6 - Exploring the universe: from the galaxies formation to Earth-like planets with the Giant Magellan Telescope
Grantee:Laerte Sodré Junior
Support type: Special Projects