[vsnet-chat 2772] Re: Periods of V1494 Aql

[Alon Retter <ar@astro.keele.ac.uk>]

Dear Mr. Lange and vsneters,

First I would like to say that these are quasi-periodicities -
there haven't been enough cycles to establish a coherent periodicity.
This is probably why you suggest 2 different periods. 

These oscillations are a well known phenomenon in some novae. It is 
called the transition phase. Other examples - Nova GK Per 1901, Nova V603
Aql 1918, the recent Nova Mus 1998.... The explanation for the phenomenon
is, however, still debated. Among the explanations offered so far:
1. Particle of dust moving in and out line of sight.
2. Winds.
3. Contractions of the white dwarf.
4. Dwarf nova outbursts (probably wrong).

The fact that the periods of the oscillations are very similar to the
time to decline by 2 magnitudes (t2) is an interesting clue for the
phenomenon. 

As both famous cases (GK Per and V603 Aql) are intermediate polar 
systems, I have recently suggested that this behaviour might be typical 
of intermediate polars. This is not an alternative explanation, but a
complementary one. A detection of a short term period in V1494 Aql might 
support this idea.

Regards,
Alon
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   Dr. Alon Retter         Tl. (work)     +44-(0)1782-58-3493  
   Physics Dept.           Fax  (work)     +44-(0)1782-711093 
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On Sat, 1 Apr 2000, Thorsten Lange wrote:

> Hello,
> I have a question about V1494 Aql:
> The nova showed a period of ~8 day from 1999/12/19 to 2000/01/07 (~1mag) 
> and then a period of ~15 days (~1-1.5mag). 
> What is the reason for both periods?
> 
> Thorsten Lange
> 
> -- 
> Thorsten Lange               
> EMail tl@thola.de
> http://thola.de/
>

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