A Photoelectric Study of the Eclipsing Variable RW Tauri.
Abstract
About 300 observations of RW Tauri were obtained on the U, B, V system with the 82- and 13-inch telescopes of the McDonald Observatory. From the depth of the total eclipse of the B star by the K-type subgiant, the magnitudes and colors of the component stars were found. A distance modulus of 8.1 mag. is then derived. A new determination of the variation in period results in an improbably high mass for the unseen campanion. Observations just after the beginning of totality give evidence for a gaseous ring heretofore observed only spectroscopically. The ring extends to 0.1 radius above the surface of the B star with about 0.001 of that star's luminosity. After correction for the intensity of this ring, a photometric solution leads to an upper limit to the limb-darkening coefficient of the B star of 0.3. The small mass function of the K star and its large radius suggest that the star may fill its equipotential surface. If this is the case, the mass ratio is found to be 4.65, which leads to masses of B = 2.550 and K = 0.550. These would make RW Tauri typical of eclipsing systems with a subgiant that is overluminous for its mass. If the equipotential surface were filled, material would be lost to the B star through the inner Lagrangian point and would produce the observed emission ring. From the shape of the equipotential surface the three axes of the elliptical K star are determined. Use of this ellipsoidal model gives a better fit to the observed light-curve, especially near first contact, than does a spherical model.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1959
- DOI:
- 10.1086/146596
- Bibcode:
- 1959ApJ...129...62G