V3890 Sagittarii

R. Gonzalez-Riestra, A. Cassatella, R. Monier, and D. de Martino, ESA International Ultraviolet Explorer Observatory, Madrid, communicate: "We report observations made with the IUE of the recurrent nova V3890 Sgr (N Sgr 1962) on May 15.2 UT. At that time, the visual magnitude of the nova, as derived from the Fine Error Sensor onboard IUE was 11.63. The spectra were taken in the low-dispersion mode (0.6 nm resolution), covering the wavelength range 120-335 nm. The ultraviolet spectrum is characterized by a faint continuum increasing towards longer wavelengths and by strong emission lines of N V 124-nm, O I 130.5-nm, Si IV 140-nm, N IV] 148.6-nm, C IV 155-nm, He II 164-nm, O III] 166.3-nm, N III] 175-nm, Si III] 189-nm, C III] 191-nm, Mg II 280-nm, [Mg V] 293-nm, the He II Paschen lines, and the O III Bowen lines. The Si III]/C III] flux ratio is consistent with an electron density < 10E10 cmE-3, if the abundances are solar. Most of the lines have a broad component (FWHM about 4000 km/s) and a narrower core (FWHM about 1200 km/s). This narrow core appears to be stronger in the high-excitation lines like He II, N V, O III, and [Mg V]. Of special interest is the very-high-ionization line of [Fe XI] at 264.8 nm, previously observed only in the sun and in the recurrent nova RS Oph during its 1985 outburst (IAUC 4067) and ascribed to the interaction of the ejected shell with pre-existing material expelled during the previous outburst. The observed flux in the [Fe XI] line is 4 x 10E-13 erg cmE-2 sE-1 and its FWHM is 800 km/s." Visual magnitude estimates (cf. IAUC 5015): May 17.87 UT, 12.1 (A. Pearce, Scarborough, W.A.); 18.07, 12.2 (P. Schmeer, Bischmisheim, W. Germany); 19.03, 12.5 (Schmeer); 19.85, 12.5 (Pearce); 20.85, 12.9 (Pearce); 21.86, 13.3 (Pearce); 22.86, 13.6 (Pearce).