Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes

Borgne, J. F. Le; Paschke, A.; Vandenbroere, Jacqueline; Poretti, E.; Klotz, A.; Boër, M.; Damerdji, Y.; Martignoni, M.; Acerbi, Francesco

doi:10.1051/0004-6361:20077957

Cited by 72 publications

(110 citation statements)

References 21 publications

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“…Clearly, the phased light curve is now much improved, but we still observe possible amplitude modulations, which may be due to the Blazhko effect. This period change rate is higher than other values found in the literature by a factor of two or more (Le Borgne et al 2007;Lee 1991;Jurcsik et al 2001), but given our limited data we cannot speculate on the cause.…”

Section: Rr Lyrae Starscontrasting

confidence: 54%

Variable stars in the globular cluster NGC 7492

Jaimes

Ferro

Bramich

et al. 2013

A&A

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Aims. We have performed a photometric V, R, I CCD time-series analysis with a baseline of about eight years of the outer-halo globular cluster NGC 7492 with the aim of searching for new variables and using these (and the previously known variables) to determine the physical parameters of interest for the cluster (e.g. metallicity, absolute magnitude of the horizontal branch, distance, etc.). Methods. We used difference image analysis to extract precise light curves in the relatively crowded star field, especially towards the densely populated central region. Several different approaches were used for variability detection that recover the known variables and lead to new discoveries. We determined the physical parameters of the only RR0 star using a light-curve Fourier decomposition analysis. Results. We found one new long-period variable and two SX Phe stars in the blue straggler region. We also present one candidate SX Phe star that requires follow-up observations. Assuming that the SX Phe stars are cluster members and using the period-luminosity relation for these stars, we estimate their distances as ∼25.2 ± 1.8 and 26.8 ± 1.8 kpc, and identify their possible modes of oscillation. We refined the periods of the two RR Lyrae stars in our field of view. We found that the RR1 star V2 is undergoing a period change and possibly exhibits the Blazhko effect. A Fourier decomposition of the light curve of the RR0 star V1 allowed us to estimate a metallicity of [Fe/H] ZW ∼ −1.68 ± 0.10 or [Fe/H] UVES ∼ −1.64 ± 0.13, a log-luminosity log(L/L ) ∼ 1.76 ± 0.02, an absolute magnitude M V ∼ 0.38 ± 0.04 mag, and a true distance modulus of μ 0 ∼ 16.93 ± 0.04 mag, which is equivalent to a distance of ∼24.3 ± 0.5 kpc. All of these values are consistent with previous estimates in the literature.

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Section: Rr Lyrae Starscontrasting

confidence: 54%

Variable stars in the globular cluster NGC 7492

Jaimes

Ferro

Bramich

et al. 2013

A&A

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“…An extensive study of the Blazhko effect is presented in the paper of Le Borgne et al (2012), which is based on observations made with TAROT telescopes (Klotz et al 2008(Klotz et al , 2009. Le Borgne et al (2012) also made use of O − C information stored in the A&A 562, A90 (2014) GEOS RR Lyr database (Le Borgne et al 2007) and gave a list of galactic field Blazhko stars. A regularly updated database of known Blazhko RR Lyraes situated in the galactic field (BlaSGalF, Skarka 2013) 2 recently contained about 270 objects.…”

Section: Introductionmentioning

confidence: 99%

Bright Blazhko RRab Lyrae stars observed by ASAS and the SuperWASP surveys

Skarka

2014

A&A

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Aims. Period study of 321 fundamental mode RR Lyrae type stars (RRab), which had appropriate data in ASAS and SuperWASP surveys, was performed to complement and extend the list of known Blazhko stars in galactic field with bright stars up to 12.5 mag in maximum light.Methods. An individual approach was applied to each studied star. Permanent visual supervision was maintained to each procedure in data analysis (data cleaning, frequency spectra examination) to avoid missing any possible sign of the Blazhko effect. Period analysis was performed using Period04 software. Results. We found 100 stars to be definitely modulated. In 25 cases, previously unknown modulation was revealed and 8 new candidates for Blazhko stars were identified. Their modulation needs to be confirmed. In 18 previously found Blazhko stars, no modulation was detectable. Multiple modulation was revealed for eight stars that were previously proposed to show simple modulation. In total, there were twelve stars with some peculiarity in their modulation in the sample. This brings the incidence rate of multiple/irregularlymodulated stars to 12%. The ratio of the modulation periods of five of the double-modulated stars was within the ratios of small integers. One of stars studied, IK Hya, showed a very interesting frequency spectrum, which we interpret as changing Blazhko period between 71.81 and 75.57 days and an additional 1403-day-long cycle analogous to a four-year cycle of the prototype RR Lyr. The limits of the shorter period produce a beating period that is approximately twice as big as a 1403-day period. The newly revealed Blazhko star RZ CVn seems to undergo changes in the amplitude of the modulation, as well as in the basic pulsation and Blazhko periods. We found that the incidence rate of the Blazhko RR Lyraes is at least 31%, more likely even higher. It was also found that the majority of the Blazhko variables show triplet structures in their frequency spectra and that in 89% of these cases, the peak with larger amplitude is on the right-hand side of the main pulsation component.

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“…The model-fitting technique (Marconi 2009) applied to a sample of RR Lyrae stars in the Large Magellanic Cloud was very useful to fix the problem of the distance scale (Marconi & Clementini 2005). Because they have been observed since the end of the XIXth century, RR Lyrae stars are also promising targets for studying stellar evolution in real time (Le Borgne et al 2007). …”

Section: Introductionmentioning

confidence: 99%

CoRoT light curves of RR Lyrae stars

Poretti¹,

Paparó

Deleuil

et al. 2010

A&A

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Context. The CoRoT (Convection, Rotation and planetary Transits) space mission provides a valuable opportunity to monitor stars with uninterrupted time sampling for up to 150 days at a time. The study of RR Lyrae stars, performed in the framework of the Additional Programmes belonging to the exoplanetary field, will particularly benefit from such dense, long-duration monitoring. Aims. The Blazhko effect in RR Lyrae stars is a long-standing, unsolved problem of stellar astrophysics. We used the CoRoT data of the new RR Lyrae variable CoRoT 101128793 ( f 0 = 2.119 d −1 , P = 0.4719296 d) to provide us with more detailed observational facts to understand the physical process behind the phenomenon. Methods. The CoRoT data were corrected for one jump and the long-term drift. We applied different period-finding techniques to the corrected timeseries to investigate amplitude and phase modulation. We detected 79 frequencies in the light curve of CoRoT 101128793. They have been identified as the main frequency f 0 and its harmonics, two independent terms, the terms related to the Blazhko frequency f m , and to several combination terms. Results. A Blazhko frequency f m = 0.056 d −1 and a triplet structure around the fundamental radial mode and harmonics were detected, as were a long-term variability on the Blazhko modulation. Indeed, the amplitude of the main oscillation is decreasing along the CoRoT survey. The Blazhko modulation is one of the smallest observed in RR Lyrae stars. Moreover, the additional modes f 1 = 3.630 and f 2 = 3.159 d −1 are detected. Taking its ratio with the fundamental radial mode into account, the term f 1 could be the identified as the second radial overtone. Detecting of these modes in horizontal branch stars is a new result obtained by CoRoT.

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Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes

Cited by 72 publications

References 21 publications

Variable stars in the globular cluster NGC 7492

Variable stars in the globular cluster NGC 7492

Bright Blazhko RRab Lyrae stars observed by ASAS and the SuperWASP surveys

CoRoT light curves of RR Lyrae stars

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