Observational studies of Cepheid amplitudes

Szabados, László; Klagyivik, P.

doi:10.1051/0004-6361/201117815

Cited by 17 publications

(18 citation statements)

References 36 publications

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“…Since there are no spectroscopic [Fe/H] values for Cepheids In a recent study Majaess et al (2013) found that the peakto-peak amplitudes of long period extragalactic Cepheids are significantly smaller at lower [Fe/H] ratio. This is just the opposite of the behaviour of the peak-to-peak amplitudes of short period Galactic Cepheids (Szabados & Klagyivik 2012a) and the R 21 and R 31 Fourier parameters in this paper, also deduced for short period Cepheids. These results are however not in conflict with the theoretical calculations.…”

Section: An Outlook For Extragalactic Cepheidscontrasting

confidence: 66%

Determination of the iron content of Cepheids from the shape of their light curves

Klagyivik¹,

Szabados²,

Szing³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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We present the study of the metallicity dependence of the Fourier amplitude ratios R 21 and R 31 for the light curves of short-period Galactic classical Cepheids in B, V, R C and I C bands. Based on the available photometric and spectroscopic data we determined the relations between the atmospheric iron abundance, [Fe/H], and the Fourier parameters. Using these relations we calculated the photometric [Fe/H] values of all program Cepheids with an average accuracy of ±0.15 dex. No spectroscopic iron abundance was known before for 14 of these stars. These empirical results provide an alternate method to determine the iron abundance of classical Cepheids too faint for spectroscopic observations. We also checked whether the metal-poor Cepheids of both Magellanic Clouds follow the same relationships, and a good agreement was found.

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Section: An Outlook For Extragalactic Cepheidscontrasting

confidence: 66%

Determination of the iron content of Cepheids from the shape of their light curves

Klagyivik¹,

Szabados²,

Szing³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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“…Berdnikov & Ivanov (1986) and Paczyński & Pindor (2000) corroborated the van Genderen (1978) conclusion concerning the amplitude-metallicity behavior of longer-period Cepheids. A recent analysis by Szabados & Klagyivik (2012) indicated that metal-poor classical Cepheids display slightly larger amplitudes than their metal-rich counterparts, a result inferred by correlating the latest abundance and photometric data for Galactic Cepheids (−0.4 [Fe/H] 0.4). Szabados & Klagyivik (2012) found the correlation strongest for shorter-period Cepheids, whereas the impact of metallicity on radial velocity and B-band amplitudes for longer-period Cepheids was less pronounced, and the coefficient for the latter was not significant (their Table 2 and Fig.…”

Section: Introductionmentioning

confidence: 84%

“…Araucaria photometry for Cepheids in NGC 6822 was published by Pietrzyński et al (2004). Following Klagyivik & Szabados (2009) and Szabados & Klagyivik (2012), peak-to-peak amplitudes were determined for the Cepheids (see also the pertinent discussion by Ngeow et al 2003). The period-amplitude results derived for the Galactic sample are similar to those found in the comprehensive analysis by Klagyivik & Szabados (2009).…”

Section: Photometrymentioning

confidence: 99%

On the metallicity dependence of classical Cepheid light amplitudes

Majaess¹,

Turner

Gieren

et al. 2012

Astrophys Space Sci

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Classical Cepheids remain a cornerstone of the cosmic distance scale, and thus characterizing the dependence of their light amplitude on metallicity is important. Period-amplitude diagrams constructed for longer-period classical Cepheids in IC 1613, NGC 3109, SMC, NGC 6822, LMC, and the Milky Way imply that very metal-poor Cepheids typically exhibit smaller V -band amplitudes than their metal-rich counterparts. The results provide an alternate interpretation relative to arguments for a null and converse metallicity dependence. The empirical results can be employed to check predictions from theoretical models, to approximate mean abundances for target populations hosting numerous long-period Cepheids, and to facilitate the identification of potentially blended or peculiar objects.

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“…In particular, Szabados & Klagyivik (2012), by using a large sample (327) of Galactic Cepheids with accurate pulsation parameters and spectroscopic metal abundances, found evidence that the luminosity and the radial velocity amplitudes slightly decrease with increasing iron abundance. However, no firm conclusion has been reached since Pedicelli et al (2010), by using a similar data set, did not find a clear dependence on metallicity.…”

Section: Luminosity Amplitudes and Metallicity Dependencementioning

confidence: 98%

On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk

Genovali

Lemasle

Bono

et al. 2014

A&A

197

262

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We present homogeneous and accurate iron abundances for 42 Galactic Cepheids based on high resolution (R ∼ 38 000) high signal-to-noise ratio (S /N ≥ 100) optical spectra collected with UVES at VLT (128 spectra). The above abundances were complemented with high-quality iron abundances provided either by our group (86) or available in the literature. We were careful to derive a common metallicity scale and ended up with a sample of 450 Cepheids. We also estimated accurate individual distances for the entire sample by using homogeneous near-infrared photometry and the reddening free period-Wesenheit relations. The new metallicity gradient is linear over a broad range of Galactocentric distances (R G ∼ 5-19 kpc) and agrees quite well with similar estimates available in the literature (-0.060 ± 0.002 dex/kpc). We also uncover evidence that suggests that the residuals of the metallicity gradient are tightly correlated with candidate Cepheid groups (CGs). The candidate CGs have been identified as spatial overdensities of Cepheids located across the thin disk. They account for a significant fraction of the residual fluctuations, and also for the large intrinsic dispersion of the metallicity gradient. We performed a detailed comparison with metallicity gradients based on different tracers: OB stars and open clusters. We found very similar metallicity gradients for ages younger than 3 Gyr, while for older ages we found a shallower slope and an increase in the intrinsic spread. The above findings rely on homogeneous age, metallicity, and distance scales. Finally, by using a large sample of Galactic and Magellanic Cepheids for which accurate iron abundances are available, we found that the dependence of the luminosity amplitude on metallicity is vanishing.

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Observational studies of Cepheid amplitudes

Cited by 17 publications

References 36 publications

Determination of the iron content of Cepheids from the shape of their light curves

Determination of the iron content of Cepheids from the shape of their light curves

On the metallicity dependence of classical Cepheid light amplitudes

On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk

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