MWC 560

R. M. Wagner and R. Bertram, Ohio State University; S. Starrfield, Arizona State University; and S. Kenyon, Center for Astrophysics, report: "Optical spectra (ranges 440-560 and 594-700 nm; resolution 0.45 nm) were obtained of MWC 560 on Oct. 23.47 UT with the Perkins 1.8-m telescope at the Lowell Observatory using the Ohio State CCD spectrograph. Features present in the spectra include H-alpha, H-beta, Fe II (multiplets 40, 42, 46, and 74), Ca I (18), and possibly He I 667.8-nm and Mn I 660.5-nm, all in emission. In addition, the 443.0- and 628.4-nm interstellar absorption features are present. The H-alpha, H-beta, and Fe II (42) lines exhibit deep P-Cyg profiles. The center of the absorption components is shifted -400 to -500 km/s and the blue edge extends to almost -1900 km/s with respect to the nominal rest wavelengths. The equivalent width of H-alpha and H-beta absorption is about 0.9 nm with FWHM about 550 km/s. The optical spectrum of MWC 560 has changed substantially since observations obtained in early Mar. (IAUC 4980, 4987, 4990) and now closely resembles that of some classical novae early in their outburst, such as QV Vul (Nova Vul 1987). Michalitsianos et al. (IAUC 5108) have suggested a similar resemblance based on ultraviolet spectra obtained on Sept. 26. These observations confirm that MWC 560 has ejected a cool, optically thick shell. It should now be monitored for the appearance of a nebular-phase spectrum and for possible dust formation as occurred early in the outburst of QV Vul."