[vsnet-chat 1599] Re: [vsnet-alert 2575] Nova Mus 98 - a possible periodicity

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

Dear Dr.  Kato,
> 
>     No, nothing is too early for such an important implication, inspiring
> these discussions.  Without your notification, the latent periodicity may
> have been overlooked forever.  It might be even possible the 0.15-mag
> variation evolve into the eclipsing feature, as was witnessed in V838 Her
> (Nova Her 1991), since both the large outburst amplitude and an early
> suggestion of periodicity may be partly explained by the large inclination.
> 
Yes, this is certainly a possibility. The large outburst amplitude and the
presence of the possible period might be explained by a magnetic nova
model, as well.

>     If the modulated light is from the secondary, it would be worth searching
> for the signature of the secondary (moving narrow emission line??).  

I believe that it might be too early to do it, because there should be
still a large contamination in the emission lines from the nebula lines,
but it worths a try.

> But, the 0.15-mag flux at mag 13 is equivalent to mag 15,which is probably
> 6 mag below the maximum.  When assuming the maximum absolute magnitude
> above -7 (for fast novae), the secondary (or the modulated component)
> should be brighter than the M_V = -1 (what temperature is expected?).
> Variation orginating from the accretion disk should be certainly as luminous,
> which implies the accretion disk is above the thermal instability line.
> In the latter case, one should consider a mechanism other than usual
> thermal disk instability in order to explain oscillations in the transition
> phase.
> 
I tend to agree with you that if the accretion disc is the dominant light 
source at this early stage of Nova Mus 98, then it should be thermally
stable. An intriguing suggestion is that the oscillations observed during
the transition phase are caused by the reformation of the accretion disc.
Anyway, this question is still opened.

Regards,
Alon Retter

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