[vsnet-campaign 207] (fwd) V1494 Aql - a photometric period of 1.5 hr - ?

[Taichi Kato <tkato>]

(fwd) V1494 Aql - a photometric period of 1.5 hr - ?

   Forwarded from [vsnet-alert 4978].  Please use this vsnet-campaign
for future timely communications regarding this campaign.

Date: Wed, 14 Jun 2000 14:23:35 +0100 (BST)
From: Alon Retter <ar@astro.keele.ac.uk>
Subject: [vsnet-alert 4978] V1494 Aql - a photometric period of 1.5 hr - ?

Dear vsneters,
 
CCD photometry of V1494 Aql (Nova Aql 1999 No. 2) during 3 nights
in 2000 June through an R-band filter with the 0.4-m telescope at 
N. Copernicus Observatory (Brno, Czech republic) reveals evidence 
for a periodicity of 1.5 hours. The peak-to-trough amplitude of the
variation is about 0.05 mag. Continuous photometry is thus highly
recommended to confirm this period and to find out its nature. Red 
filters are preferred, but other bands are fine.

Cor. of the nova (J2000.0):
19h 23m 05s.38
+04o 57' 20".1
 
V magnitude: mV~10.3
 
Why is it important:

1. The nova is very bright now. When the nova fades it will
   be much harder to confirm the presence of the periodicity.

2. Observing the nova at this stage should teach us about the
   evolution of the accretion activity in the nova at this stage
   and onwards.

3. If the 1.5-h is the orbital period of the nova, it will be the 4th
   confirmed nova below the period gap. Novae with periods below the
   gap are important since Retter & Naylor (2000) suggested that
   post-novae below the gap don't return fast to their pre-outburst
   magnitudes as novae above the gap do. This might be the first evidence
   for mass transfer cycles in CVs.

4. If the period is a superhump period, then the orbital period will be
   very similar, and the conclusions of section 3. stay the same.

5. If the 1.5-h is the spin period of the nova, and the orbital period
   will be longer, then the nova should be an intermediate polar. 
   V1494 Aql had oscillations during its transition phase. Thus this 
   would confirm Retter, Liller and Gerrard (1999) suggestion of a link
   between intermediate polars and the oscillations / dust during the
   transition phase in classical novae.

Regards,
Alon
-------------------------------------------------------------------------
   Dr. Alon Retter         Tl. (work)     +44-(0)1782-58-3493
   Physics Dept.           Fax  (work)     +44-(0)1782-711093 
   Keele University        -----------------------------------
   Staffordshire           'As a scientist I don't believe myself, so  
   ST5 5BG, U.K.            why should I believe you?' (A.R. 1965-2085)  
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