New Results of the Konkoly Blazhko Group Johanna Jurcsik Konkoly Observatory Santa Fe, 2009, New Mexico, USA Stellar Pulsation: Challenges for Theory and Observation

The Konkoly Blazhko Survey ( ) PIs: J. Jurcsik & B. Szeidl PIs: J. Jurcsik & B. Szeidl PhD students: Á. Sódor & Zs. Hurta PhD students: Á. Sódor & Zs. Hurta co-workers: undergraduate/graduate students co-workers: undergraduate/graduate studentsAims: To obtain extended, accurate, multicolour light curves of modulated and unmodulated RRab stars in order to in order to derive the incidence rate of the modulation inderive the incidence rate of the modulation in the sample the sample study long term changes in the pulsation and modulation propertiesstudy long term changes in the pulsation and modulation properties find any changes in the physical parameters of the stars during the Blazhko cyclefind any changes in the physical parameters of the stars during the Blazhko cycle

24” telescope, Konkoly Observatory, Svábhegy, Budapest Results are obtained utilizing Recent CCD observations obtained with an automatic 60cm telescopeRecent CCD observations obtained with an automatic 60cm telescope Archive Konkoly photometric data spanning over 80 yearsArchive Konkoly photometric data spanning over 80 years

The observed light curves cover the whole pulsation light curve in different phases of the modulation

Multicolour data V – (B-V) V – (V-I C ) (B-V) – (V-I C )

Results 1 First detection of small-amplitude, First detection of small-amplitude, short period modulations short period modulations mmag amplitudes of the modulation mmag amplitudes of the modulation frequency components frequency components Jurcsik, Sódor, Váradi et al. 2005, A&A 430, 1049 Jurcsik, Szeidl, Sódor et al. 2006, AJ 132, 61 Jurcsik, Hurta, Sódor et al. 2009, MNRAS in press

SS Cnc P mod =5.3 d RR Gem P mod =7.2 d SS Cnc P mod =5.3 d RR Gem P mod =7.2 d DM Cyg P mod =10.6 d BR Tau P mod =19.3 d

Results 2 First systematic survey dedicated to determine the frequency of the to determine the frequency of the occurrence of the modulation occurrence of the modulation Konkoly Blazhko Survey I (0.35d < P < 0.50d) Konkoly Blazhko Survey I (0.35d < P < 0.50d) from 30 RRab 14 show the Blazhko effect from 30 RRab 14 show the Blazhko effect 47% incidence rate 47% incidence rate Konkoly Blazhko Survey II (0.55d < P < 0.6d) in progress Konkoly Blazhko Survey II (0.55d < P < 0.6d) in progress from 11 RRab 6 show the Blazhko effect from 11 RRab 6 show the Blazhko effect 55% incidence rate 55% incidence rate 50% of RRab stars show the Blazhko effect 50% of RRab stars show the Blazhko effect previous estimates gave 15-30% incidence rate previous estimates gave 15-30% incidence rate

detection of quintuplet frequencies in the spectrum of RV UMa Hurta, Jurcsik, Szeidl & Sódor 2008, AJ, 135, 957 detection of higher modulation multiplets in the spectrum of MW Lyr Jurcsik, Sódor, Hurta et al. 2008, MNRAS 391, 164 unambiguous detection of f m in the spectra of accurate, extended data of Blazhko stars in all the Konkoly Blazhko data detection of multiple periodic modulations Sódor et al 2006 Sódor 2009 Results 3 First light curves suitable to study the ‘fine structure’ of the spectrum ‘fine structure’ of the spectrum

exponential / linear decrease of the pulsation / modulation components pulsation / modulation components fmfmfmfm asymmetric triplets quintuplets schematic amplitude spectrum of UZ Vir schematic amplitude spectrum of UZ Vir similar amplitudes of the pulsation and modulation components in high orders secondary modulation

Results 4 temporal occurrence of the modulationtemporal occurrence of the modulation significant changes in the properties of the modulationsignificant changes in the properties of the modulation Sódor, Szeidl, Jurcsik 2007 A&A 469, 1033 Sódor, Szeidl, Jurcsik 2007 A&A 469, 1033 Sódor 2009, CoAst 159, 55 Sódor 2009, CoAst 159, 55

RR Geminorum amplitude of phasemodulation amplitude modulation

RY Comae

CZ Lacertae P mod1 =18.51 d 2005 P mod2 =14.80 d P mod1 =18.51 d 2005 P mod2 =14.80 d P mod1 =18.68 d 2006 P mod2 =14.31 d P mod1 =18.68 d 2006 P mod2 =14.31 d P m1 /P m2 ≈ 5/4 P m1 /P m2 ≈ 4/3

Interpretation 1 Amplitude and phase modulations of a harmonic function describe the observed frequency spectrum of Blazhko stars very well: asymmetric amplitudes of the modulation side frequencies occurrence and rapid amplitude decrease of the higher order multiplets of the modulation frequency components (f 0 if m ) components (f 0  if m ) m(t)=a [1+b  sin  t+  sin  t  c sin  t  m(t)=a [1+b  sin  t+  sin  t  c sin  t  Af 0 A(f 0 f m ) A(f 0  f m ) A(f 0 2f m ) A(f 0  2f m ) A(f 0 3f m ) A(f 0  3f m )    Szeidl & Jurcsik, CoAst submitted Phase difference of amplitude and phase modulations

Interpretation 2 Jurcsik, Sódor, Hurta et al, 2008, MNRAS 391, 164 Jurcsik, Sódor, Hurta et al, 2008, MNRAS 391, 164 Separation of amplitude and phase modulation componets by transforming the data according to the phase variation of f 0 Analytically, phase modulation is equivalent with Analytically, phase modulation is equivalent with periodic changes of the pulsation period (f 0 ). periodic changes of the pulsation period (f 0 ).

Interpretation 3 Our observations and their interpretation indicate that: the physically meaningful frequency of thethe physically meaningful frequency of the Blazhko effect is f m Blazhko effect is f m the pulsation period and the amplitude of the radial mode pulsation change with the modulation periodthe pulsation period and the amplitude of the radial mode pulsation change with the modulation period the global physical parameters of the star (,, ) vary during the Blazhko cyclethe global physical parameters of the star (,, ) vary during the Blazhko cycle Jurcsik, Szeidl, Sódor et al. 2006, AJ 132, 61 Jurcsik, Szeidl, Sódor et al. 2006, AJ 132, 61 Jurcsik Sódor, Szeidl et al, 2009, MNRAS 393, 1553 Jurcsik Sódor, Szeidl et al, 2009, MNRAS 393, 1553 Jurcsik, Hurta, Sódor et al, 2009, MNRAS in press Jurcsik, Hurta, Sódor et al, 2009, MNRAS in press with the Blazhko cycle periodic, structural changes in the with the Blazhko cycle periodic, structural changes in the stars occur which result in period and amplitude changes stars occur which result in period and amplitude changes of the pulsation of the pulsation Stothers 2006, ApJ 652, 643 Stothers 2006, ApJ 652, 643 Further theoretical studies are needed to identify the Further theoretical studies are needed to identify the „triggering mechanism” of the Blazhko modulation „triggering mechanism” of the Blazhko modulation

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