[vsnet-campaign-nova 946] Re: V2540 Oph - detection of period/s

[Alon Retter <retter@Physics.usyd.edu.au>]

Dear Taichi (or whoever wrote the email below - please identify
yourself!),

I've heard Nir Shaviv's talk in the nova conference in Sitges and have
already printed his summary mentioned below for further reading.

While Nir has a simple theoretical explanation to the transition phase,
it does not mean that it is the correct one! At the same meeting I 
presented my model (but haven't sent my summary to the preprint archive 
yet due to some technical problems and lack of time). The idea that the
transition phase is connected with intermediate polars gives a simple
answer to the question `why we observe this phase only in a small part of
the nova population'. This is since about 15% of CVs are classified as 
intermediate polars and about 20% of all novae have the transition phase.

In addition, I presented this idea in the Oxford conference about 4 years
ago, and gave a simple prediction: every nova that shows the transition
phase should be an intermediate polar system. It looks as if the
prediction has become true in 3 (probably 4) cases. The proposed
connection is thus very significant. To my understanding this means that 
my model is no worse than Nir Shaviv's and actually has an advantage
(predictive power). Have Nir Shaviv given any predictions that have
become true?

As for the physics behind my model, I suggested that the reformation of
the accretion disc after the nova outburst in intermediate polars and the
interaction of the inner part of the disc with the magnetosphere of the
white dwarf is the reason for the oscillations. This leads to the
formation of winds that block the radiation from the white dwarf so dust
blobs may form, so this idea is not far removed from Nir Shaviv's model. I
have discussed this model with 3 theoreticians, however the way the inner
part of the disc interacts with the magnetosphere of the white dwarf is
still an open question, so unfortunately a complete model with specific
numbers cannot be calculated at the moment with current knowledge. 
 
My model is so simple to confirm or refute, so why not test it by further
observations?

Regards,
Alon
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   Dr. Alon Retter          Tel. (work)     +61-2-9351-4058
   School of Physics        Fax  (work)     +61-2-9351-7726
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On Wed, 31 Jul 2002, Taichi Kato wrote:

> Re: V2540 Oph - detection of period/s
> 
> Alon,
> 
> > The ~2.5-h period could be the binary orbital period. It would be then in
> > the period gap of cataclysmic variables. If other periods are confirmed
> > the nova would be an intermediate polar supporting the possible connection
> > between the transition phase in novae and intermediate polars. As
> > observations of 3 recent novae (V1494 Aql 1999/2, V382 Vel 1999, V1039 Cen
> > 2001) are consistent with this prediction, V2540 Oph will be the 4th
> > case, so the proposed connection becomes highly significant.
> 
>     The transition phase oscillations of novae now seem to be better
> understood as a natural consequence of an instability in the super-Eddington
> winds.  A good summary just appeared in astro-ph (see below).  Your
> interpretation, lacking comparable physics, is only too less appealing.
> 
> Paper: astro-ph/0207639
> From: Nir J. Shaviv <shaviv@phys.huji.ac.il>
> Date: Mon, 29 Jul 2002 22:40:16 GMT   (241kb)
> 
> Title: Classical Novae as Super-Eddington Objects
> Authors: Nir J. Shaviv (Racah Inst of Physics, Hebrew University, Jerusalem)
> Comments: 6 pages, 7 figures, to appear in the proceedings of the International
>   Conference on Classical Nova Explosions, Sitges, Spain, 20-24 May 2002
> \\
>   Several of the inconsistencies plaguing the field of novae are resolved once
> we consider novae to be steady state super-Eddington objects. In particular, we
> show that the super-Eddington shell burning state is a natural consequence of
> the equations of stellar structure, and that the predicted mass loss in the
> super-Eddington state agrees with nova observations. We also find that the
> transition phase of novae can be naturally explained as "stagnating" winds.
> \\ ( http://arXiv.org/abs/astro-ph/0207639 ,  241kb)
> 
>

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