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13.1-minute variations of MV Lyr
MV Lyr has been observed in the Crimean Astrophysical Observatory
by K.A.Antoniuk and N.M.Shakhovskoy during 12 nights using the
5-channel photometer-polarimeter constructed by V.Piirola.
Recently the star has shown a return to its active state
(for historical light curve, see
Andronov I.L., Fuhrmann B., Wenzel W. MV Lyrae : Entering the
Period Gap ?-Astronomische Nachrichten, 1988, vol.309, N.1, P.39-42.
and refs therein)
On JD 2452619-625, the mean brightness was <V>=13.79 with
a r.m.s. deviation from the mean of sigma=0.19, then the star became brighter
<V>=12.64 (sigma=0.15) (JD 2452675-731). The most recent night
JD 2452740 had shown an additional increase of the mean brightness to
<V>=12.35 (sigma=0.07).
At his high state, the variations at 13 minute time scale have appeared.
The periodogram analysis of the deviations of the observations from the
running parabola fit (Andronov I.L. Method of running parabolae: spectral
and statistical properties of the smoothing function.- Astron. Astrophys.Suppl.,
1997, Vol. 125, No 1, 207-217.) with a filter half-width Delta t=15days
has shown a lot of peaks corresponding to the orbital scale variability,
as well as to the short-term oscillations.
The highest peak corresponds to an ephemeris:
TMax(U) = HJD 2452734.63125 + .00904586 * E (JD 2452723-740)
+- .00007 +-.00000010
TMax(R) = HJD 2452737.05132 + .00912842 * E (JD 2452731-740)
+-.00008 +-.00000017
The effective semi-amplitude of the variations decreases with wavelength
(0.038+-.002 in U and 0.022+-.001 in R), but there seem to be a modulation
of the amplitude with time.
The one per cent discrepancy between the periods in the ephemeris corresponds
to a daily bias (i.e. 110.548 and 109.548 cycles per day, respectively),
thus new observations are needed to make a proper cycle numbering and to
check possible coherency of such oscillations.
Such a period has not been detected during previous active states
in 1989
(Andronov I.L., Borodina I.G., Chinarova L.L., Fuhrmann B., Kolesnikov
S.V., Korth S., Pavlenko E.P., Pikhun A.I., Shakhovskoj N.M., Shugarov
S.Yu., Wenzel W. MV Lyrae: the cataclysmic variable, which
returned to its normal activity state.- Commun.Spec. Astron.Obs., 1992,
v.69, p.125-136.)
in 1992-1993 (Kraicheva Z., Stanishev V., Genkov V.
MV Lyrae: Photometric study at high state,
Astron. Astrophys. Suppl. Ser. 134, 263--270 (1999))
or in 1996 (Pavlenko E.P., Shugarov S.Yu. Photometric study
of the nova-like variable MV Lyrae during an enormous outburst
in 1997, Astron. Astrophys. 343, 909--915 (1999))
I.L.Andronov il-a@mail.ru , http://il-a.pochtamt.ru
K.A.Antoniuk antoniuk@crao.crimea.ua
N.M.Shakhovskoy shakh@crao.crimea.ua
Return to the Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
