1. C R I M E A Activity of five WZ Sge- type systems in a few years after their outbrsts E.P. Pavlenko, O.I. Antoniuk, K.A. Antoniuk, D.A. Samsonov, A.V. Baklanov, A.V. Golovin, M.V. Andreev Tübingen 2010

2. 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.

3. Observatory on the peak Terskol Crimean astrophysical observatory CCD Photometry of the WZ Sge-type dwarf novae WZ 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

4. 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.

5. WZ Sge What 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 month after 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

6. WZ Sge in 7 years after the 2001 outburst

7. Porb = 81.6 min The profile of orbital light curve could change from one orbital cycle to another one. The less- amplitude hump could be splitted or has a reduced amplitude

8. WZ Sge in 7 years after the 2001 outburst

12. The character of the spectrum represents rather a shot noise

13. V1108 Her Candidate 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

14. V1108 Her In the 4 year after the 2004 outburst Porb = 0.05672 d Epsilon = 0.0187 q= 0.091 m2 = 0.064 (for m1 = 0.7 Mo) Secondary is the late-type star (brown dwarf) passed minimum of orbital periods Example of original nightly light curve Search for the orbital period Periodogram for 8 nights in June-July, 2008

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

16. P1 P2 V1108 Her at some nights in June 2008 dispayed 21.6-min (P1) periodical light variations, while in July 2008 there were 17.3-min (P2) light variations. A~0.01 mag Both variations are not in-phase however. They do not seem to be connected with WD pulsations They coincide with Kepler orbits at 0.36 a– 0.41 a (outer disk!) Search for the short light variations in V1108 Her: After orbital curve subtracting there is 0.01-mag variability

17. SDSS J0804 Porb = 0.0590048 d (Pavlenko and Malanushenko, 2009) q = 0.062 m2 = 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

18. 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

19. 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.

20. SDSS J1021 Candidate to Porb = 0.055988 (Uemura et al., 2008) 2008: Observations with 2.6-m telescope (CrAO) in 3 years after 2006 outburst

21. SDSS J102146.44+234926.3 in 3 year after 2006 outburst Jan 20/21 2009 P = 0.013674 d A = 0.1 mag

22. 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 occasions of 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)

23. ASAS J0025 Candidate 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

24. ASAS J0025 Do not confirm the 0.05654 d candidate to orbital period (Templeton et al., 2006) No reasonable orbital frequences (the registered frequences do not fit the epsilon – Porb relation 0.06207 d 0.05854 d 0.05535 d 0.02805 d “Quasi-orbital period”

25. CONCLUSION

26. 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

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

28. Thank you!