Tidal effects in pulsating stars. III - L = 1 /p 5/ modes in the ellipsoidal variable 14 Aurigae A

Abstract

The noneclipsing single-lined spectroscopic binary 14 Aur A has a circular orbit of period 3.78858 days, and the A9 IV primary is a delta Scuti variable. Analysis of our 158 hours of blue light photometry obtained on 40 nights in 1972--1975 and of others' radial velocity measures provides an identification of three standing wave (in the rotating frame) pulsation modes as the tidal m=0, +- 1 substates belonging to an l=1 surface harmonic, with periods, P/sub 1,+1/=0./sup d/088088, P/sub 1,0/=0./sup d/096533, and P/sub 1,-1/=0./sup d/088243. These l=1 surface harmonics are probably p/sub 5/ global modes. The observed amplitudes A/sub l/m of these periods P/sub l/m, when combined with approximate theoretical visibility functions for the integrated flux variations (for l< or approx. =2, vertical-barmvertical-bar< or approx. =l) and with the assumption of energy equipartition among the observed substates, lead to an orbital inclination i=21./sup 0/2 ( +- 1./sup 0/4). The photometrically defined ellipticity of figure of the primary, the orbital velocity variation, published uvby..beta.. photometry and calibrations, pulsation theory, double-star theory, and stellar evolution theory all combine to yield these system characteristics: T/sub e,1/=7900 +- 110 K; M/sub 1//Msun=2.6 +- 0.7; /Rsun=5.2 +- 0.7; /Lsun=96 +- 26; Q/sub 1/=0./sup d/0124 +- more » 0./sup d/0011; M/sub 2//Msun=1.1 +- 0.3. The relative differences in the principal semiaxes are (b/sub 1/--b/sub 2/)/ =0.022 +- 0.004 and (b/sub 2/--b/sub 3/)/=0.025 +- 0.004 if rotation is synchronous with orbital motion. Both components of the binary are well detached from their respective Roche lobes. The relative amplitudes and phase of the pulsations in light and velocity agree satisfactorily with both theory and other observations. « less