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Astron. Astrophys. 347, L39-L42 (1999)

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Letter to the Editor

The 1999 outburst of the eclipsing and recurrent nova U Scorpii *

U. Munari 1,3, T. Zwitter 2, T. Tomov 1,3, P. Bonifacio 4, P. Molaro 4, P. Selvelli 5, L. Tomasella 1, A. Niedzielski 6 and A. Pearce 7

1 Osservatorio Astronomico di Padova, Sede di Asiago, I-36032 Asiago (VI), Italy
2 University of Ljubljana, Department of Physics, Jadranska 19, 1000 Ljubljana, Slovenia
3 CISAS - Center of Studies and Activities for Space, University of Padova "G.Colombo", Italy
4 Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste, Italy
5 CNR-GNA-Osservatorio Astronomico di Trieste Via Tiepolo 11, I-34131 Trieste, Italy
6 Centre for Astronomy, N.Copernicus University, ul. Gagarina 11, PL-87100 Torun, Poland
7 32 Monash Ave, Nedlands, WA 6009, Australia

Received 26 May 1999 / Accepted 15 June 1999


The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and recurrent nova U Sco is presented. The photometric evolution closely matches that of the previous events. The FWZI=10,000 km sec-1 for emission lines at maximum has decreased to 4000 km sec-1 by day +23, with continuous and dramatic changes in the line profiles. No nebular line has become visible and the ionization degree has increased during the brightness decline. A not previously reported and quite puzzling splitting of the emission lines into three components after the first two weeks is outstanding in our spectra. The radiated luminosity is found to be a tiny fraction of that of classical novae for any reasonable distance to U Sco.

Key words: stars: individual: U Scorpii – stars: novae, cataclysmic variables

* Based on observations collected with the telescopes of the European Southern Observatory at La Silla, Chile and of the Padova & Asiago Astronomical Observatories (Italy)

Send offprint requests to: U. Munari (munari@pd.astro.it)

© European Southern Observatory (ESO) 1999

Online publication: June 6, 1999