27. Variable Stars

Detre, L.; Eggen, O. J.; Bojarčuk, A. A.; Herbig, G. H.; Kippenhahn, Rudolf; Kwee, K.K.; Odgers, G. J.

doi:10.1017/s0251107x00023750

Cited by 3 publications

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“…Although the modulation period was dubious, the fact of modulation itself seemed to be unambiguous. In contrast, in the 1950s the modulation seemed to cease (Detre 1970). We continued to observe RR Gem in 2004 and 2005 and found it to be modulated but with very low amplitude and with the shortest period (7.216 d) known at that time (Jurcsik et al 2005a;Sódor 2006).…”

Section: Introductionmentioning

confidence: 61%

The Blazhko behaviour of RR Geminorum II

Sódor¹,

Szeidl²,

Jurcsik³

2007

A&A

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Context. RR Gem is one of the few Blazhko RR Lyrae that has photometric observations available extended enough to study the long-term courses of its pulsation and modulation properties in detail. Aims. We investigate the pulsation and modulation properties and the relations between them in RR Gem using photometric observations from the past 70 years in order to gain further insight into the nature of the Blazhko modulation. Methods. We studied the photographic, photoelectric, and CCD light curves obtained at the Konkoly Observatory and other authors' published maxima observations. Detailed analysis of the light curves, maximum brightness, and O-C data are carried out. Results. RR Gem showed modulation most of the time it was observed. The modulation amplitude showed strong variations from the undetectable level (less than 0.04 mag in maximum brightness) to about 0.20 mag. The amplitudes of the amplitude and phase modulations showed parallel changes, thus the total "power" of the modulation have changed during the past 70 years. Parallel changes in the pulsation and modulation periods occur with a dP mod /dP puls = 1.6 ± 0.8 × 10 3 ratio. We also detected 0.05−0.1 mag changes in the mean maximum brightness and mean pulsation amplitude.

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Section: Introductionmentioning

confidence: 61%

The Blazhko behaviour of RR Geminorum II

Sódor¹,

Szeidl²,

Jurcsik³

2007

A&A

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“…Three of them were supposed to have light curves stable enough to be used for the calibration of the formulae which express the physical parameters of the variables from the parameters of the light curves (TZ Aur, SS Cnc, and RR Gem; Jurcsik & Kovács 1996). Eight targets had no detailed photometry previously (BH Aur, BK Cas, EZ Cep, SS Cnc, CZ Lac, TW Lyn, ET Per, BR Tau, UZ UMa) and two variables were suspected to be modulated, but the observations were contradictory (RR Gem: Balázs-Detre 1960;Detre 1970;Jurcsik et al 2005a;MW Lyr: Gessner 1966;Mandel 1970;Sódor & Jurcsik 2005).…”

Section: Resultsmentioning

confidence: 99%

Studying Blazhko RR Lyrae stars with the 24‐inch telescope of the Konkoly Observatory

Sódor

2007

Astron Nachr

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About a dozen field RR Lyrae stars have been observed with the 24-inch Heyde-Zeiss telescope of the Konkoly Observatory at Svábhegy, Budapest, since its refurbishment in 2003. Most of the observing time is allocated for the investigation of the Blazhko modulation, a phenomenon that still does not have a satisfactory explanation. The obtained multicolour CCD observations are unique in extent. The accuracy of the measurements makes it possible to detect low amplitude modulation of the light curve as well. The discovery of Blazhko stars with low modulation amplitudes warns that the incidence rate of the Blazhko modulation is, in fact, much larger than it was previously expected. This makes the efforts exploring the cause of the modulation even more important. A summary of our measurements and results achieved during the last 3 years is presented.

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“…In this respect RR Geminorum provides a very interesting case. Detre (1970) remarked that his unpublished photographic observations from the 1930s demonstrated the Blazhko effect in RR Gem, but (in his words) it "ceased to exist since about 1940". That the Blazhko effect might be temporary in nature may be crucial in understanding the physical background of the phenomenon.…”

Section: Introductionmentioning

confidence: 99%

The Blazhko behaviour of RR Geminorum I

Jurcsik¹,

Sódor

Váradi

et al. 2005

A&A

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Abstract. Extended CCD monitoring of RR Gem revealed that it is a Blazhko type RRab star with the shortest Blazhko period (7.d 23) and smallest modulation amplitude (∆M max < 0.1 mag) currently known. The short period of the modulation cycle enabled us to obtain complete phase coverage of the pulsation at each phase of the modulation. This is the first multicolour observation of a Blazhko star which is extended enough to define accurate mean magnitudes and colours of the variable at different Blazhko phases. Small, but real, changes in the intensity mean colours at different Blazhko phases have been detected. The Fourier analysis of the light curves shows that, in spite of the mmag and smaller order of the amplitudes, the triplet structure is noticeable up to about the 14th harmonic. The modulation is concentrated to a very narrow, 0.2 phase range of the pulsation, centred on the supposed onset of the H emission during rising light. These observational results raise further complications for theoretical explanation of the long known but poorly understood Blazhko phenomenon.

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27. Variable Stars

Cited by 3 publications

References 0 publications

The Blazhko behaviour of RR Geminorum II

The Blazhko behaviour of RR Geminorum II

Studying Blazhko RR Lyrae stars with the 24‐inch telescope of the Konkoly Observatory

The Blazhko behaviour of RR Geminorum I

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