Analysis of the possible Blazhko‐effect Cepheid V473 Lyrae

Molnár, L.; Szabados, László; Dukes, R. J.; Győrffy, Á.; Szabo, Robert M.

doi:10.1002/asna.201211975

Cited by 10 publications

(14 citation statements)

References 24 publications

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“…It is much less common among other radial pulsators, however. Despite the fact that we know many double-mode Cepheids with amplitude and phase modulations [1], there is only one Galactic Cepheid (V473 Lyrae) with confirmed periodic amplitude and phase variations similar to the Blazhko effect observed in RR Lyrae stars [2].…”

Section: Introductionmentioning

confidence: 89%

Long term light curve variations of theKeplerCepheid V 1154 Cyg

Kanev

Саванов

Sachkov

2015

EPJ Web of Conferences

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Abstract. We present a period analysis of the light curve and its Fourier parameters of the bright Cepheid V1154 Cyg (P=4.925454 days) based on the observations by the Kepler space telescope. Fourier parameters R 21 , R 31 clearly indicate variations with a period of 158.2 ± 1 days (more than 5σ peak in the power spectrum) with a very small amplitude (0.265-0.275 for R 21 , 0.065-0.071 for R 31 ) making impossible to detect it with groundbased observations. Finally we discuss that this effect is similar to the Blazhko effect in RR Lyrae stars.

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Section: Introductionmentioning

confidence: 89%

Long term light curve variations of theKeplerCepheid V 1154 Cyg

Kanev

Саванов

Sachkov

2015

EPJ Web of Conferences

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“…However, several studies have shown that, in addition to the secular period changes known since long (Szabados 1983;Berdnikov & Ignatova 2000;Pietrukowicz 2001Pietrukowicz , 2002Poleski 2008;Turner et al 2006), fluctuations of pulsation periods and amplitudes are present in some, if not all, Cepheids. An early example of this was V473 Lyr, which exhibits periodic variations of its light and radial velocity amplitude, similar to RR Lyrae stars exhibiting the Blazhko effect (Burki et al 1982;Molnár et al 2013). Space-based photometry obtained with the Kepler, MOST, and BRITE satellites has revealed a host of variations in the fundamentalmode Cepheid V1154 Cyg (Derekas et al 2012;Kanev et al 2015;Derekas et al 2017), found long-period modulation in T Vul (Smolec et al 2016a) and suggested a greater degree of irregularity exhibited by first-overtone (FO) Cepheids (Evans et al 2015).…”

Section: Introductionmentioning

confidence: 97%

Investigating light-curve modulation via kernel smoothing – II. New additional modes in single-mode OGLE classical Cepheids

Süveges

Anderson

2018

Monthly Notices of the Royal Astronomical Society

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Detailed knowledge of the variability of classical Cepheids, in particular their modulations and mode composition, provides crucial insight into stellar structure and pulsation. However, tiny modulations of the dominant radial-mode pulsation were recently found to be very frequent, possibly ubiquitous in Cepheids, which makes secondary modes difficult to detect and analyse, since these modulations can easily mask the potentially weak secondary modes. The aim of this study is to re-investigate the secondary mode content in the sample of OGLE-III and -IV single-mode classical Cepheids using kernel regression with adaptive kernel width for pre-whitening, instead of using a constant-parameter model. This leads to a more precise removal of the modulated dominant pulsation, and enables a more complete survey of secondary modes with frequencies outside a narrow range around the primary. Our analysis reveals that significant secondary modes occur more frequently among first overtone Cepheids than previously thought. The mode composition appears significantly different in the Large and Small Magellanic Clouds, suggesting a possible dependence on chemical composition. In addition to the formerly identified non-radial mode at P 2 ≈ 0.6 . . . 0.65P 1 (0.62-mode), and a cluster of modes with near-primary frequency, we find two more candidate non-radial modes. One is a numerous group of secondary modes with P 2 ≈ 1.25P 1 , which may represent the fundamental of the 0.62-mode, supposed to be the first harmonic of an l ∈ {7, 8, 9} non-radial mode. The other new mode is at P 2 ≈ 1.46P 1 , possibly analogous to a similar, rare mode recently discovered among first overtone RR Lyrae stars.

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“…Recently, Anderson (2014, henceforth: A14) reported the discovery of modulated radial velocity (RV) variability of four Cepheids, two of which-QZ Nor and V335 Pup-are short-period Cepheids likely to pulsate in the first overtone and candidates for Blazhko-effect-like long-timescale modulations (years) similar to the enigmatic V473 Lyr (Burki et al 1982;Molnár et al 2013). The two additional Cepheids presented in A14-Car and RS Pup-are long-period Cepheids for which significant RV curve modulations among consecutive pulsation cycles were detected, varying in particular the RV amplitude.…”

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confidence: 99%

Discovery of cycle-to-cycle modulated spectral line variability and velocity gradients in long-period Cepheids

Anderson

2016

Mon. Not. R. Astron. Soc.

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This work reports the discovery of cycle-to-cycle modulated spectral line and atmospheric velocity gradient variability in long-period Cepheids based on 925 high-resolution optical spectra of Carinae (P ∼ 35.5 d) recorded during three heavy duty-cycle monitoring campaigns (in 2014, 2015, and 2016). Spectral line variability is investigated via crosscorrelation functions (CCFs) computed using three sets of spectral lines (weak, solar, strong). A metallic line velocity gradient, δv r (t), is computed as the difference between weak and strong-line RVs. CCF shape indicators BIS (asymmetry), FWHM, and depth all exhibit clear phase-dependent variability patterns that differ from one pulsation cycle to the next. Weakline CCFs exhibit these effects more clearly than strong-line CCFs. BIS exhibits the most peculiar modulated variability and can be used to identify the presence of cycle-to-cycle modulated line profile variations. δv r (t) clearly exhibits cycle-to-cycle differences that correlate very closely with modulated BIS variability, suggesting perturbations of the atmospheric velocity field as the cause for modulated spectral line variability. These perturbations are most significant during contraction and are not in phase with the pulsation, transmitting information between consecutive pulsation cycles. This work shows RV curve modulation to be a consequence of atmospheric velocity gradient perturbations. Possible origins of these perturbations and their impact on Cepheid RV measurements as well as the projection factor used in Baade-Wesselink-type distance determinations are discussed.

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Analysis of the possible Blazhko‐effect Cepheid V473 Lyrae

Cited by 10 publications

References 24 publications

Long term light curve variations of theKeplerCepheid V 1154 Cyg

Long term light curve variations of theKeplerCepheid V 1154 Cyg

Investigating light-curve modulation via kernel smoothing – II. New additional modes in single-mode OGLE classical Cepheids

Discovery of cycle-to-cycle modulated spectral line variability and velocity gradients in long-period Cepheids

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