Bibcode
Pereyra, A.; Magalhães, A. M.; de Araújo, F. X.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 495, Issue 1, 2009, pp.195-199
Advertised on:
2
2009
Revista
Número de citas
3
Número de citas referidas
3
Descripción
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.
Based on observations obtained at the Observatório do Pico dos
Dias, LNA/MCT, Itajubá, Brazil.