H alpha spectropolarimetry of the B[e] supergiant GG Carinae

Author(s)

Pereyra, A. ^[1] ; de Araujo, F. X. ^[1] ; Magalhaes, A. M. ^[2] ; Fernandes, M. Borges ^[3] ; de Souza, A. Domiciano ^[3]

Affiliation

^[1] Observ Nacl, BR-20921400 Rio De Janeiro - Brazil

^[2] Univ Sao Paulo, IAG, Dept Astron, BR-05508900 Sao Paulo - Brazil

^[3] Univ Nice Sophia Antipolis, CNRS, Observ Cote Azur, H Fizeau UMR 6525, Nice - France

• Document type: Journal article
• Source: Astronomy & Astrophysics; v. 508, n. 3, p. 1337-1341, DEC 2009.
• Web of Science Citations: 9

Abstract

Aims. We study the geometry of the circumstellar environment of the B{[}e] supergiant star GG Car. Methods. We present observations acquired using the IAGPOL imaging polarimeter in combination with the Eucalyptus-IFU spectrograph to obtain spectropolarimetric measurements of GG Car across Ha at two epochs. Polarization effects along the emission line are analysed using the Q-U diagram. In particular, the polarization position angle (PA) obtained using the line effect is able to constrain the symmetry axis of the disk/envelope. Results. By analysing the fluxes, GG Car shows an increase in its double-peaked Ha line emission relative to the continuum within the interval of our measurements (similar to 43 days). The depolarization line effect around Ha is evident in the Q-U diagram for both epochs, confirming that light from the system is intrinsically polarized. A rotation of the PA along Ha is also observed, indicating a counter-clockwise rotating disk. The intrinsic PA calculated using the line effect (similar to 85 degrees.) is consistent between our two epochs, suggesting a clearly defined symmetry axis of the disk. (AU)

• FAPESP's process: 01/12589-1 - Stars, the interstellar medium and their interrelationships
• Grantee: Antônio Mário Magalhães
• Support Opportunities: Research Projects - Thematic Grants