SPATIALLY-RESOLVED OPTICAL SPECTROSCOPY OF THE HERBIG-AE VEGA-LIKE BINARY STAR HD-35187

We report on observations of the young binary system HD 35187 (SAO 771 44). For the first time, we have obtained spatially resolved optical s pectra of the individual stars. Analysis of their effective temperatur es indicates that the stars have spectral types of A2 (HD 35187B) and A7 (HD 35187A). Analysis of the Hy Balmer line indicates a luminosity class V for both stars. At the time of these observations, net Ha emis sion was present only towards HD 35187B. However, there is evidence th at the photospheric Ha line in HD 35187A has been 'filled in' relative to its expected strength in an A7 star, so this star may also be asso ciated with some process leading to H alpha emission. Moreover, both s tars exhibit absorption in the He I lambda 5876 line well in excess of that expected for their spectral types. Comparison with earlier obser vations reveals that both the H alpha and He I lines are variable, so both stars are 'active' in some sense. We suggest that the variable He I absorption detected towards both stars is a result of chromospheric activity, and is not necessarily related to the circumstellar environ ment. We find tentative evidence for a narrow Ca K circumstellar absor ption line and excess redshifted absorption of the Na D line profiles in the spectrum of HD35187B, both of which are absent in the spectrum of HD35187A. The heliocentric radial velocity of the presumed circumst ellar Ca K line (+ 54.5 km s(-1)) is similar to that of redshifted cir cumstellar absorption lines previously identified in IUE spectra of th is star, and the velocity range of the Na D absorption precisely match es that of the UV circumstellar components. Moreover, by placing the s tars on the HR diagram (with the aid of the reliable Hipparcos distanc es) we find evidence that HD 35187B is dimmed by about 0.4 mag of grey circumstellar extinction. The detection of net H alpha emission, circ umstellar absorption lines, and significant circumstellar extinction f or HD 35187B suggests that it has far more mass in its circumstellar e nvironment than its companion, and that the observed IR excess of this system originates from a disc surrounding HD 35187B alone.