A recent issue of ApJ (Gies et al. 1998, ApJ, 493, 440) contains our report on new UV spectroscopy made with the Hubble Space Telescope and Goddard High Resolution Spectrograph of the unusual binary system, Phi Persei. This system contains a rapidly rotating Be star orbiting a hitherto unseen companion in a 127 day orbit. The new HST/GHRS spectra show for the first time clear evidence of the companion's spectrum: it is a hot (53000 K), small star (1 solar mass) which is presumably the stripped-down remains of a much more massive star which lost both mass and angular momentum to the companion (which is spinning at close to the critical break-up speed). The new results are important for several reasons:
The Outreach Office of the Space Telescope Science Institute was interested in making a WWW News Release about this work, but we needed some kind of image to accompany the text. I contacted Bill Pounds, an astronomical artist living here in the Atlanta, and with the help of Jon Bjorkman (University of Toledo) and others, Bill produced a beautiful and, hopefully, accurate rendering of what Phi Persei might look like close up. The painting and press release are available on the WWW at URL http://oposite.stsci.edu/pubinfo/pr/97/39.html. A full size version is available from http://oposite.stsci.edu/pubinfo/pr/97/39/content/phiperp.jpg.
The painting depicts the binary system for an assumed inclination of 80 degrees and an orbital phase just prior to primary superior conjunction. The Be primary (upper right) appears oblate and gravity darkened because of its extremely fast rotation (V sin i = 450 km s-1). The surrounding circumstellar disk was made assuming a Gaussian intensity distribution based on interferometric measurements {Quirrenbach et al. 1997, ApJ, 479, 477) and the Hipparcos distance estimate (220 pc), and the red colour reflects the dominance of the H-alpha flux. The inner edge of the disk facing the companion has a brighter appearance because we believe it is heated there by the secondary (observed in the appearance of Fe IV shell lines in the HST spectra at this orbital phase). The hot subdwarf secondary appears in the foreground (lower left) with radial features suggesting its strong stellar wind (see Thaller et al. 1995, ApJ, 448, 878). The secondary also has a circumstellar disk (seen in the He II 4686 line) which we imagine results from infall from the Be star's disk. Hopefully future interferometric observations will show how closely this painting matches the real situation. |
