SIMULTANEOUS OPTICAL AND UV SPECTRA OF THE TWO LMC NOVAE 1988 H. Drechsel and J. Andreae Dr. Eemeis Observatory Bamberg Astronomical Institute of the University Erlangen-Nuernberg, P.E.G. S. Starrfield Department of Physics and Astronomy Arizona State University, Tempe, AZ, U.S.A. G. Sonneborn IUE Observatory, NASA Goddard Space Plight Center Greenbelt, MD, U.S.A. ABSTRACT The two classical novae of 1988 in the LMC are the first extragalactic novae, which have been studied in the UV range. IUE spectra were taken under the Nova Target of Opportunity program, and quasi-simultaneous optical spectra were obtained by the authors. The spectral development in the UV and visual ranges is discussed for both objects. NOVA LMC 1988 No.1 The outburst of the classical nova N LMC 1988 No. 1 was discovered on March 21, 1988. The first IUE (SWP+LWP) spectra were taken only a few days later between March 25-30, 1988. An extensive set of UV spectra covers the subsequent outburst phases until the late nebular stage in May 1989. Quasi-simultaneous optical spectra in the range 380-710 nm were obtained during the early decline with the ESO 1.52m + B&C + CCD on March 26-29. The overall spectral appearance and development suggest no evident deviations from the behavior of similar galactic novae, and are especially reminiscent of Nova V1668 Cyg (1978). The chemical com- position of the ejecta is compatible with a CO-type white dwarf. The UV spectra of the early outburst stages show emissions of C I-II, Si I-II, Pe I-II, Al II, Ni II, Mg II. Mg II (280) has a marked P Cyg profile with an absorption edge at about -2000 km/s. Until the end of April, a strengthening of the far UV continuum was observed and accom- panied by an increase in ionization stage. The resonance fluorescence line of 0 I (130.4) exhibits drastic variations during the early phases: it is absent shortly after outburst, becomes the strongest UV line in late April and May, and then gradually decreases and vanishes in July 1988. By the end of May, a wide range of ionization potential is present (0 I - N V). Intercombination lines like C IIl[ 190.9, N III} 175.0, N IVJ 148.6, 0 III] + C III 232.6 increase in strength. A late nebular spectrum of May 8, 1989i contains only high ionization, inter- combination and forbidden lines. The strongest lines in the early outburst visual spectra are the Balmer series lines, He I (587.6) and Pe II lines (e.g. at 492, 502, 518 nm), superimposed on a relatively strong continuum increasing towards the blue edge of the visual range. The lines have distinct P Cyg profiles, with absorption velocities of about -1000 to -1500 km/s. The PWHM of the emissions amounts to about 1200 km/s. use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100068494 Downloaded from https://www.cambridge.org/core. IP address: 107.175.206.216, on 14 Jun 2019 at 02:31:07, subject to the Cambridge Core terms of