The evidence for the presence of optically thick winds, produced by classical novae after optical maximum, has been challenged in recent papers. In addition, signs of orbital phase dependent photometric variations, sometimes seen quite early in the d
evelopment of nova outbursts, are hard to interpret in the framework of optically thick envelopes and especially winds. A general discussion for belief in the presence of optically thick winds with increasing ejection velocities during the early stages of novae after their explosion, must be given. This has to be done in order to clarify ideas about novae as well as to contribute in particular to the understanding of the behaviour of novae V1500 Cyg and V1493 Aql showing phase dependent variations during very early decline after the outburst. Possible ways of overcoming the apparent contradiction of phase dependent variations through the production of deviations from spherical symmetry of the winds, are looked at and order of magnitude estimates are made for different theoretical scenarios, which might produce such deviations. It is found that large deviations from spherical symmetry of the optically thick winds in early phases after the explosion can easily explain the problem of variations. In particular, the presence of a magnetic field might have had a non-negligible effect on the wind of V1500 Cyg, while at the present there is not enough information available concerning V1493 Aql. Optically thick winds/envelopes are almost certainly present in the early stages after optical maximum of a nova, while it is difficult to make pure Hubble flow models fit the observations of those stages. New more detailed observational and theoretical work, in particular including the effects of magnetic fields on the winds, is needed.
We study the long term, S Dor-type variability and the present hot phase of the LBV star GR290 (Romanos Star) in M33 in order to investigate possible links between the LBV and WNL stages of very massive stars. We use intermediate resolution spectra,
obtained with WHT in December 2008, when GR290 was at minimum (V = 18.6), as well as new low resolution spectra and B V R I photometry obtained with the Loiano and Cima Ekar telescopes during 2007-2010. We identify more than 80 emission lines in the 3100-10000 A range, belonging to different species and to forbidden transitions. Many lines, especially the HeI triplets, show a P Cygni profile with an a-e radial velocity difference from -300 to -500 km/s. The shape of the 4630-4713 A emission blend and of other emission lines resembles that of WN9 stars; the blend deconvolution shows that the HeII 4686 A has a strong broad component with FWHM simeq 1700 km/s. During 2003-2010 the star underwent large spectral variations, best seen in the 4630-4686 A emission feature. Using the late-WN spectral types of Crowther & Smith (1997), GR290 apparently varied between the WN11 and WN8-9 spectral types, the hotter being the star the fainter its visual magnitude. This spectrum-visual luminosity anticorrelation of GR290 is reminiscent of the behaviour of the best studied LBVs. During the 2008 minimum we find a significant decrease in bolometric luminosity, which could be attributed to absorption by newly formed circumstellar matter. We suggest that, presently, the broad 4686 A line and the optical continuum are formed in a central WR region, while the narrow emission line spectrum originate in an extended, slowly expanding envelope, that is composed by matter ejected during previous high luminosity phases, and ionized by the central nucleus. GR290 could have just entered in a phase preceeding the transition from the LBV state to late WN type.
