1201.4561 (Michael Friedjung)
Michael Friedjung
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 development 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.
View original:
http://arxiv.org/abs/1201.4561
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