Hα spectropolarimetry of the B[e] supergiant GG Carinae
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 Hα 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 Hα line emission relative to the continuum within the interval of our measurements (~43 days). The depolarization line effect around Hα 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 Hα is also observed, indicating a counter-clockwise rotating disk. The intrinsic PA calculated using the line effect (~85°) is consistent between our two epochs, suggesting a clearly defined symmetry axis of the disk.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2009
- DOI:
- 10.1051/0004-6361/200913250
- arXiv:
- arXiv:0910.5569
- Bibcode:
- 2009A&A...508.1337P
- Keywords:
-
- polarization;
- stars: individual: GG Car;
- circumstellar matter;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 5 pages, 3 figures, accepted by Astronomy and Astrophysics