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Astron. Astrophys. 318, 908-924 (1997)

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1. Introduction

Nova V 1974 Cygni (= Nova Cygni 1992) was discovered by Collins (1992) on February 19, 1992 - the day of the outburst. It reached visual maximum V = 4.4 on February 22 - the day of maximum. It is the brightest nova in the northern hemisphere since 1975 and due to favourable circumstances it is the best-studied nova in the history of astronomy.

It is not the purpose of the paper to review all work done in connection with the outburst of this most interesting nova. Instead, we shall concentrate on a rediscussion of the kinematics of the expanding envelopes of the nova in view of the unique situation provided by the early imaging of the nova envelope with the HST FOC camera. Paresce (1994) determined the distance of the nova in a rather straightforward way, using the angular radius of the nebular envelope and the velocity of its expansion as deduced from early IUE spectra (1500 km s-1). The distance derived by him d = (3.2 [FORMULA] 0.5) kpc is surprisingly large and at variance with most of the distance estimations that employed conventional indirect methods. Paresce et al. (1995) extended the range of possible distances from 1.8 to 3.2 kpc assuming the emitting material is expanding at 830 - 1500 km s-1. Thus here we also attempt to clarify the cause of the uncertainty.

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998