High Resolution Time-Resolved UCLES Spectroscopy of AE Aquarii: I. The Secondary Star Revealed (Abstract)

Volume 35 number 1 (2007)

J. Echevarria

F. Diego

D. Mills

R. C. Smith

Abstract

(Abstract only) High-dispersion time-resolved spectroscopy of the cataclysmic variable AE Aqr has been obtained. The emission lines have a complex structure that make it difficult to measure the motion of the white dwarf. The cross-correlation for the absorption lines shows a clear asymmetric profile, as expected from a heated side of the red star. The spectral type for the secondary star varies from K2 to K5; there are clear indications that the temperature varies as a function of star longitude. The radial velocity analysis yields Kab = 165.2 ± 0.6 Km s–1 for the cross-correlated secondary star. The rotational velocity of the red star has been measured as a function of orbital period. It shows ellipsoidal variations with a period half the orbital period. The rotational velocities vary within the range Vrot sin i = 105 ± 3 Km s–1 and Vrot sin i = 130 ± 3 Km s–1. The former can be used to constrain the white dwarf semi-amplitude value to yield Kem = 139 ± 4 Km s–1, consistent with derived values from published radial velocity measurements. From a variation in the absorption line strength of 30%, we constrain the inclination angle to i = 58° ± 3. The estimated masses of the binary are: Mw = 1.07 ± 0.07 Mù and Mr = 0.90 ± 0.05 Mù. If this is correct we should expect a spectral type of G5 if the secondary star is a main sequence star. We suggest that the discrepancy is explained if the star has a radius 40% greater than a main sequence star for a mass of 0.90 Mù.