A model of the Algol type close binary TT hydrae |
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Authors: | A G Kulkarni K D Abhyankar |
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Institution: | (1) Centre of Advanced study in Astronomy, Osmania University, 500007 Hyderabad;(2) Present address: SardarPatel Planetarium, Sayaji Baug, 390018 Baroda |
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Abstract: | UBV photometric observations and elements of TT Hydrae obtained by Kulkarni and Abhyankar (1980) are combined with the radial
velocity curve of Popper (1979, personal communication) to derive the absolute dimensions and. a model of this important Algol
system. While the photometric ratios of radii inV andB are in agreement givingk = 0.3812 for a limb darkening coefficient ofx = 0.6, application of Irwin’s (1947) method givesx = 0.4 forU. The primary is found to be a main sequence Al V star of mass 2.61M
⊙ and radius 2.01 R⊙, and the secondary is classified as a Kl III star of mass 0.70M
⊙ and radius 5.33R
⊙. The observed Fourier coefficients for the light outside the eclipse agree with those calculated from theory for the reflection
and ellipticity effects. The system shows an ultraviolet excess of 0.5 to 0.6 magnitudes during primary eclipse, which is
attributed to an asymmetric circumstellar distribution of matter around the primary. The evolutionary status of the secondary,
which does not appear to fill its Roche lobe completely, is discussed. |
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Keywords: | close binaries absolute dimensions ultraviolet excess in Algols |
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