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The Blazhko modulation of RRab stars Recent results Johanna Jurcsik Konkoly Observatory

The Blazhko modulation of RRab stars Recent results Johanna Jurcsik Konkoly Observatory. JENAM 2008, VIENNA, Austria Asteroseismology and Stellar Evolution. Full access to an automatized 60cm telescope. Konkoly Observatory, Svábhegy, Budapest.

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The Blazhko modulation of RRab stars Recent results Johanna Jurcsik Konkoly Observatory

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  1. The Blazhko modulation of RRab starsRecent resultsJohanna Jurcsik Konkoly Observatory JENAM 2008, VIENNA, Austria Asteroseismology and Stellar Evolution

  2. Full access to an automatized 60cm telescope Konkoly Observatory, Svábhegy, Budapest 90% of the telescope time is dedicated to observations of RR Lyrae stars 5 years ~700 nights of observations ~4000 hours

  3. Astrophysical importance of RR Lyrae stars The physics of radial mode stellar pulsation is well known Their evolutionary state is well known Observations can be accurately modelled Theoretical calibrating objects of Stellar pulsation Stellar evolution Indicators of Universal distance scale Chemical composition distribution

  4. The Blazhko effect Its reason is still unknown! Its amplitude can be commensurable with the amplitude of the pulsation The residual light curve after the removal of the mean pulsation light curve has large amplitude at around maximum/minimum light

  5. The Konkoly Blazhko Survey (2003-2008) • Aims: • To define the true incidence rate of the modulation • To obtain extended, accurate, multicolour light curves • of modulated and unmodulated RRab stars

  6. Modulation frequencies in the Fourier spectrum Previously found: symmetric or asymmetric equidistant triplets at the pulsation frequency components The fm moduation frequencywas not undaubtedly detected spectrum of MW Lyr in the vicinity of 2f0 The modulation frequency appears in the spectra of all the Blazhko stars with extended obervations triplet kf0 ± fm quintuplet kf0 ± 2fm septuplet kf0 ± 4fm kf0 ± 12.5fm The colour behaviour (AB/AV, AV/AI) of fm is discrepant from the colour behaviour of the pulsation and modulation side frequencies The real frequency of the modulation is most probably the modulation frequency and not any of the side lobe frequencies !

  7. Detection of small-amplitude modulations BR Tau Pmod=19.3d RR Gem Pmod=7.2 d DM Cyg Pmod=10.6d SS Cnc Pmod=5.3 d

  8. Statistics ~50% (14/30) of RRab stars show the Blazhko effect The selection of targets was to observe stars with no previous accurate light curves 15-30% was detected in previous surveys (MACHO, OGLE) Histograms of the amplitude distributions of the highest modulation frequency components The modulation has SMALL amplitude in half of the Blazhko stars Small-amplitude modulations were not detected in any of the previous surveys

  9. Temporal occurrence and significant changes in the modulation RY Com 2007 2008 RRGem 1935-36 1938-53 1958-59 1965-83 2004-05 Amplitude of phase modulation amplitude modulation

  10. Is Blazhko modulation a common property of RRab stars ? -- mmag amplitude of the modulation is also possible -- the modulation may occur temporarily

  11. We obtained extended multicolour light curves of large modulation Blazhko stars for the first time The light curves cover the whole pulsation light curve in different phases of the modulation

  12. colour-magnitude and two-colour loops of the pulsation of MW Lyr in 20 phases of the modulation V – (B-V) V – (V-IC) (B-V) – (V-IC)

  13. MW Lyrae 2006 2007 Complex phase and amplitude modulations

  14. MW Lyrae Phase modulation = pulsation period changes With a simple transformation according to the phase of f0 the modulation become pure amplitude modulation

  15. Changes in the observed derived mean quantities of MW Lyr derived (B-V) (V-I) <B-V> <V-I> <B>-<V> <V>-<I> (V) <V> Perpuls Amppuls R/Rsun Vrad L/Lsun Teff <Teff> <L/LSun> <Vm> <Vi> <loggeff> <R/RSun> Pulsation phase

  16. Previously knownRecent results of the Konkoly Survey Only large amplitude modulations were known Discovery of small amplitude modulations Modulation appears in the spectrum as doublets/triplets, the modulation frequency was not definitely identified Quintuplets, septuplets and fm identified in the spectra The occurrence rate of the modulation was estimated 15-30% The detected incidence rate is ~50% No observations covering the whole pulsation in different phases of the modulation were previously obtained The global mean physical parameters of the star do vary during the Blazhko cycle based on our colour observations

  17. References of the Konkoly Blazhko Survey : • Jurcsik, J., Sódor, Á., Szeidl, B., Váradi, M., Hurta, Zs., Posztobányi, K., Vida, K., Dékány, I., Hajdu, G., Kővári, Zs., Nagy, I.:Is light-curve modulation a common property of RRab stars?2008, ApJ, submitted • Jurcsik, J., Sódor, Á., Szeidl, B., Kolláth, Z., Smith, H. A., Hurta, Zs., Váradi, M., Henden, A., Dékány, I., Nagy, I., Posztobányi, K., Szing, A., Vida, K., Vityi, N.: An extensive photometric study of the Blazhko RR Lyrae star MW Lyr: II. Changes in the physical parameters, • 2008, MNRAS, submitted • Jurcsik, J., Sódor, Á., Hurta, Zs., Váradi, M., Szeidl, B., Smith, H. A., Henden, A., Dékány, I., Nagy, I., Posztobányi, K., Szing, A., Vida, K., Vityi, N.: An extensive photometric study of the Blazhko RR Lyrae star MW Lyr: I. Light curve solution,2008, MNRAS, in press • Sódor, Á., Jurcsik, J., Szeidl, B.: A new method for determining physical parameters of fundamental mode RR~Lyrae stars from multicolour light curves2008, MNRAS, submitted • Hurta, Zs., Jurcsik, J., Szeidl, B., Sódor, Á.: First Quintuplet Frequency Solution of a Blazhko Variable: Light Curve Analysis of RV Uma,2008, AJ, 135, 957 • Hurta, Zs.: The Blazhko behavior of RV Uma,2007, AN, 328, 841 • Sódor, Á., Szeidl, B., Jurcsik, J.: The Blazhko behaviour of RR Geminorum II. Long-term photometric results,2007, A&A, 469, 1033 • J. Jurcsik, B. Szeidl, Á. Sódor, I. Dékány, Zs. Hurta, K. Posztobányi, K. Vida, M. Váradi, and A. Szing: The shortest modulation period Blazhko RR Lyrae star: SS Cnc2006, AJ, 132, 61 • J. Jurcsik, Á. Sódor, M. Váradi, B. Szeidl, A. Washüettl, M. Weber, I. Dékány, Zs. Hurta, B. Lakatos, K. Posztobányi, A. Szing, and K. Vida: The Blazhko behaviour of RR Geminorum I, CCD photometric results in 2004,2005, A&A, 430, 1049 • Jurcsik, J., Sódor, Á., Szeidl, B., Váradi, M., Hurta, Zs., Posztobányi, K., Vida, K., Dékány, I., Hajdu, G., Kővári, Zs., Nagy, I., Koponyás, B., Vityi, N., Szing, A., Kun,.E.: • Multicolour light curves of RRab stars, 2005-2008, IBVS No 5709, 5793, 5844, 5846

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