Volume 495, Number 1, February III 2009
|Page(s)||195 - 199|
|Section||Interstellar and circumstellar matter|
|Published online||14 January 2009|
Hα spectropolarimetry of RY Tauri and PX Vulpeculae*
Observatório Nacional, Rua General José Cristino 77, São Cristovão, 20921-400 Rio de Janeiro, Brazil e-mail: firstname.lastname@example.org
2 Departamento de Astronomia, IAG, Universidade de São Paulo, Rua do Matão 1226, São Paulo, SP 05508-900, Brazil
Accepted: 17 November 2008
Aims. To detect line effects using spectropolarimetry in order to find evidence of rotating disks and their respective symmetry axes in T Tauri stars.
Methods. We used the IAGPOL imaging polarimeter along with the Eucalyptus-IFU to obtain spectropolarimetric measurements of the T Tauri stars RY Tau (two epochs) and PX Vul (one epoch). Evidence of line effects showing a loop in the Q-U diagram favors a compact rather than an extended source for the line photons in a rotating disk. In addition, the polarization position angle (PA) obtained using the line effect can constrain the symmetry axis of the disk.
Results. RY Tau shows a variable Hα double peak in 2004-2005 data. A polarization line effect is evident in the Q-U diagram for both epochs confirming a clockwise rotating disk. A single loop is evident in 2004 changing to a linear excursion plus a loop in 2005. Interestingly, the intrinsic PA calculated using the line effect is consistent between our two epochs (~167°). An alternative intrinsic PA computed from the interstellar polarization-corrected continuum and averaged between 2001-2005 yielded a PA ~ 137°. This last value is closer to perpendicular to the observed disk direction (~25°), as expected from single scattering in an optically thin disk. For PX Vul, we detected spectral variability in Hα along with non-variable continuum polarization when compared with previous data. The Q-U diagram shows a well-defined loop in Hα associated with a counter-clockwise rotating disk. The symmetry axis inferred from the line effect has a PA ~ 91°(with an ambiguity of 90°). Our results confirm previous evidence that the emission line in T Tauri stars has its origin in a compact source scattered off a rotating accretion disk.
Key words: polarization / stars: individual: RY Tau / stars: individual: PX Vul / stars: circumstellar matter
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.