Stokes imaging of AM Her systems using 3D inhomogeneous models - I. Description of the code and an application to V834 Cen

Autor(es)

Costa, J. E. R. ^[1] ; Rodrigues, C. V. ^[1]

Afiliação do(s) autor(es)

^[1] Inst Nacl Pesquisas Espaciais, MCT, BR-12227010 Sao Jose Dos Campos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 398, n. 1, p. 240-248, Sept. 2009.
• Área do conhecimento: Ciências Exatas e da Terra - Astronomia
• Notas: O processo está em nome de Antônio Mário Magalhães
• Citações Web of Science: 7
• Assunto(s): Instrumentação (astronomia) Transferência radiativa Campo magnético Polarização

Resumo

Polars (or AM Her systems) are cataclysmic variables without a disc due to the strong magnetic field of the white dwarf. Most of their emission comes from the region where the accretion column impacts the white dwarf and cools through cyclotron and bremsstrahlung processes. We present a new code, cyclops, to model the optical emission from these systems including the four Stokes parameters. It considers a three-dimensional region with the electronic density and temperature varying following a shock-like profile and a dipolar magnetic field. The radiative transfer is solved in steps considering the solution with non-null input radiation. The footprint of the column in the white dwarf surface is determined by the threading region in the equatorial plane, i.e. the region from where the flow follows the magnetic lines. The extinction caused by the Thomson scattering above the emitting region is optionally included. The search for the model parameters that best fit an observational data set is carried out using a hybrid approach: a genetic algorithm is used to seek for the regions of the parameter space having the best models and then an amoeba code refines the search. An example of the application to multi-wavelength data of V834 Cen is presented. The fit found is consistent with previous parameter estimates and is able to reproduce the features of V834 data in three wavebands. (AU)

• Processo FAPESP: 01/12589-1 - Stars, the interstellar medium and their interrelationships
• Beneficiário: Antônio Mário Magalhães
• Modalidade de apoio: Auxílio à Pesquisa - Temático