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Observations of the ZZ Ceti star KUV 08368+4026

Observations of the ZZ Ceti star KUV 08368+4026. Chun Li Beijing Normal University. Overview. Introduction of ZZ Ceti stars New observations for KUV 08368+4026 Data Reduction Preliminary Results Future Work. Introduction of ZZ Ceti Stars. ZZ Ceti stars (DAV white dwarfs):

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Observations of the ZZ Ceti star KUV 08368+4026

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  1. Observations of the ZZ Ceti star KUV 08368+4026 Chun Li Beijing Normal University

  2. Overview • Introduction of ZZ Ceti stars • New observations for KUV 08368+4026 • Data Reduction • Preliminary Results • Future Work

  3. Introduction of ZZ Ceti Stars ZZ Cetistars (DAV white dwarfs): －have the lowest Teff among the four classes of variable white dwarfs (DAV, DBV, DOV, PNNV) －at the cross of the extension of the Cepheid instability strip and the evolution tracks of white dwarfs.

  4. Pure instability strip

  5. Stucture of White Dwarfs

  6. The DAVs (ZZ Ceti) More than 140 members Periods: 100 s – 1500 s Stucture: C/O core, He layer, H envelope Instability: κ-mechanism Teff: ~12500 K  ~11000 K; Pulsation modes: g modes

  7. Discovered in Feb.1996 With the 1.9m telescope at Haute Provence Observatory V=15.55 mag B-V=0.22 U-B=-0.59 (Vauclair et. al. 1997) ZZ Ceti Star KUV 08368+4026

  8. Journal of new observations in B

  9. 2.4m Telescope of Lijiang

  10. 2.16m Telescope of Xinglong

  11. 1.5m Telescope of SPM

  12. Feb 2009 Light Curve

  13. Power spectrum(Feb 2009)

  14. Data analysis： Period04

  15. List of Frequencies ------------------------------------------- Freq Err Ampl Err S/N ------------------------------------------- 3247.7690 0.0321 5.283 0.218 15.49 3249.1089 0.0623 2.722 0.218 7.97 3885.5344 0.0154 11.008 0.218 17.11 3886.7449 0.0359 4.729 0.218 7.38 3887.7290 0.0101 16.751 0.218 26.04 5223.7930 0.0718 2.363 0.218 7.09 5747.6812 0.0570 2.974 0.218 9.19 6386.5161 0.0651 2.606 0.218 8.70 7134.3735 0.0364 4.659 0.218 16.13 ------------------------------------------ ------------------------------------------- Freq Err Ampl Err S/N ------------------------------------------- 1386.9042 0.0430 3.944 0.218 15.04 1454.6732 0.0464 3.653 0.218 10.06 1976.4851 0.0157 10.828 0.218 20.88 2159.0911 0.0566 2.995 0.218 9.38 2498.7566 0.0160 10.596 0.218 24.90 2500.7136 0.0194 8.757 0.218 20.78 2757.8711 0.0736 2.304 0.218 5.63 2759.9866 0.0467 3.633 0.218 8.82 3245.5122 0.0571 2.970 0.218 8.76 3246.7395 0.0130 13.052 0.218 38.44 -------------------------------------------

  16. Result: 1）19 periods were founded 2）8 independent modes 3）Periods identification: l=1, 2 4）Triple Periods: average δf=1.12 µHz →rotationalPeriod: P=3.09 day 5）Average ΔP=32.6 s for l=1 → M=0.6-0.7 M⊙

  17. Light Curve(Dec 2009 part 1)

  18. Light curve(Dec 2009 Part 2)

  19. Light Curve(Jan 2010)

  20. Future work To finish data reduction Period analysis To get stellar parameters Theoretical study with the white dwarf Modelling Code (France)

  21. Thanks!

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