c r i m e a activity of five wz sge- type systems in a few years after their outbrsts e.p. pavlenko,...

C RI M E

A

Activity of five WZ Sge-type systems in a few

years after theiroutbrsts

E.P. Pavlenko, O.I. Antoniuk, K.A. Antoniuk, D.A. Samsonov, A.V. Baklanov, A.V. Golovin,

M.V. Andreev

Tübingen 2010

The most promising objects for the search for accreting WD pulsators are the low mass transferring CVs with evolved secondaries, WZ type stars.

The aim of this work is the search for the potential pulsating accreting WDs among the 5 CVs in minimum including continuation of monitoring of known pulsating WD in SDSS J0804 together with study of the activity of these binary components in several years after their outbursts.

Observatory on the peak Terskol

Crimean astrophysical observatory

CCD Photometry of the WZ Sge-type dwarf novaeWZ Sge,V1108 Her and SDSS J 1021 has been

carried out with 2.6-m Shajn telescope in CrAO,ASAS J0025 and SDSS J0804 were observed with 2.6-m Shajn telescope in CrAO and 2-m

telescope in Terskol observatory

During this searching it is necessary to consider the observational evidences of activity connected with different components of binary system: accretion disc, hot spot, accretion stream, secondary component.

It is widely known that the orbital profile of WZ Sge type stars in quiescence is the two-humped one. As it was shown earlier for SDSS J0804 (Pavlenko, 2008), the orbital profile could sometimes be three- , or four- humped one (splitting of one or both humps). That could produce one specific problem: the corresponding periodogram will display a strong peak pointing to ¼ Porb.

For these stars having orbital periods ~ 80-90 min., ¼*Porb = 20 – 23 min.

That value is also comparable with the longest WD pulsations.

That also corresponds to the potential instabilities in outer disk orbit.

So if somebody find in quiescence such periodicities, it is difficult to distinguish immediately weather they are connected with orbital period, WD pulsations or disk instability.

WZ SgeWhat do we know on periodicities in WZ Sge itself?

Porb = 0.0567 d (Krzeminski, 1962; Warner, 1976); 2-humped eclipsed light curve (eclipse of AD)

28 s oscillations (Robinson, Nather and Patterson, 1978)

15-s oscillations; Twd = 25 000 K from Far-UV spectroscopy in 1 monthafter 2001 outburst (Araujo-Betancor et al., 2004)

q = 0.045 (Patterson et al., 2002)

2008: Observations with 2.6-m telescope (CrAO) in 7 years after 2001 outburst

WZ Sge in 7 years after the 2001 outburst

WZ Sge in 7 years after the 2001 outburst

Porb = 81.6 min

The profile of orbitallight curve could changefrom one orbital cycleto another one. The less-amplitude hump could be splitted or has a reduced amplitude

WZ Sge in 7 years after the 2001 outburst

WZ Sge in 7 years after the 2001 outburst

WZ Sge in 7 years after the 2001 outburst

WZ Sge in 7 years after the 2001 outburst

WZ Sge in 7 years after the 2001 outburst

The character of the spectrumrepresents rather a shot noise

V1108 HerCandidate to Porb = 0.05703 (Kato et al., 2009 ) 0.05686 (Price et al., 2004)

2008: Observations with 2.6-m telescope (CrAO) in 4 years after 2004 outburst

V1108 Her In the 4 year after the 2004 outburst

Porb = 0.05672 dEpsilon = 0.0187q= 0.091m2 = 0.064 (for m1 = 0.7 Mo)

Secondary is the late-typestar (brown dwarf) passedminimum of orbital periods

Example of original nightly light curve

Search for the orbital period

Periodogram for 8 nights in June-July,2008

Averaged original data folded on Porb. A ~0.06 – 0.08 mag. The second hump could be splitted or almost totally absent.

P1

P1

P2

P2

V1108 Her at some nights in June 2008 dispayed 21.6-min (P1) periodical light variations,

while in July 2008 therewere 17.3-min (P2) light variations. A~0.01 mag

Both variations arenot in-phase however.They do not seem to beconnected with WD pulsations

They coincide with Keplerorbits at 0.36 a– 0.41 a (outer disk!)

Search for the short light variations in V1108 Her:After orbital curve subtractingthere is 0.01-mag variability

SDSS J0804Porb = 0.0590048 d (Pavlenko and Malanushenko, 2009)

q = 0.062m2 = 0.047 (Pavlenko and Malanushenko, 2009)

Ppuls = 12.6 min (Pavlenko, 2008)

2009: Observations with 2.6-m telescope (CrAO) and 60-cm (Terskol) in 3 years

after 2006 outburst

SDSS J0804 in 3 year after the 2006 outburst

Ongoing monitoring of nonradial WD pulsations

Mean puls profile: A~0.02 – 0.025 mag

Evolution of the orbital light curves over 2009

Periodograms:original and after

orbital curves subtraction

The non-radial pulsations in 2009

appeared not every night

The 12.6-min (= 756 s) non-radial pulsations appeared in 8-9 months

after the 2006 outburst (Pavlenko, 2008).

It stably existed and has been drifted in the range 732 – 768 s during the

2007 – 2009 years (Malanushenko, Pavlenko, Malanushenko, 2010 in press).

Since 2009 the appearance of these pulsations became unstable.

The first disappearance of pulsations was registered in ~2 year

after their first detection.

SDSS J1021Candidate to Porb = 0.055988 (Uemura et al., 2008)

2008: Observations with 2.6-m telescope (CrAO) in 3 years after 2006 outburst

SDSS J102146.44+234926.3 in 3 year

after 2006 outburst

Jan 20/21 2009

P = 0.013674 dA = 0.1 mag

The light variability for January – April 2008 was not presented every night. When It was observable, it appeared in the vicinity of 0.0137 d.

1/4 x Porb (like in several occasionsof SDSS J0804)? - But the absence of modulation at some dates; not all of the rest curves are in phase;

Unstable pulsations?

Kepler orbit of accretion disk?- (in this case R = 0.40a)

ASAS J0025Candidate to Porb = 0.05654 d (Templeton et al., 2006)q = 0.045?

2007: Observations with 2-m telescope (Terskol) in 4 years after 2004 outburst

ASAS J0025

Do not confirm the 0.05654 d candidate to orbital period(Templeton et al., 2006)

No reasonable orbital frequences(the registered frequences donot fit the epsilon – Porb relation

0.06207 d0.05854 d

0.05535 d

0.02805 d

“Quasi-orbital period”

CONCLUSION

Orbital: WZ Sge, SDSS J0804, V1108 Her have two-humped light curve. The less hump could be splitted or even absent. The systems are high-inclined

WZ Sge V1108 HerSDSS J0804

We did not confirm the candidates to orbital periods for SDSS J1021 and ASAS J0025

Orbital:: WZ Sge, SDSS J0804, V1108 Her have two-humped light curve. The less hump could be splitted or even absent. The systems arerather high-inclined

WD: SDSS J0804 that displayed 12.6-min stable pulsations during 2 years,Is no longer the “stable pulsator” in 3 years after the 2006 outburst.

Secondary: V1108 Her q = 0.091 is a new WZ Sge type dwarf nova with brown dwarf

Disc: probably instabilities in outer disc at 0.36a – 0.41a In SDSS J1021 and ASAS J0025 ? Shot-noice model of AD in WZ Sge?

“Quasi-orbital period” in ASAS J0025

ASAS J0025 and SDSS J1021 are the low-inclined systems

Thank you!