Search for Evolutionary Changes in the Periods of Cepheids: V1033 Cyg, a Classical Cepheid at the First Crossing of the Instability Strip

Бердников, Л. Н.; Pastukhova, E. N.; Kovtyukh, V. V.; Lemasle, B.; Kniazev, A. Y.; Усенко, И. А.; Bono, G.; Grebel, Eva K.; Hajdu, G.; Zhuiko, S. V.; Udovichenko, S. N.; Keir, L. E.

doi:10.1134/s1063773719040017

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…2. The O-C diagram covering more than 100 years indicates a rapid increase of the period of 18.2 s/yr, in agreement with a first crossing of the instability strip for this star (Berdnikov et al 2019).…”

Section: Resultssupporting

confidence: 79%

“…Period. Using only the photoelectric moments of maximum from paper by Berdnikov et al (2019), current quadratic light elements of V1033 Cyg are obtained: MaxHJD = 2452701.6164+4.9494727 E + +0.14237 10 −5 E 2 , the phases calculated for these elements are given in Table 1. The phase curve V1033 Cyg from our observations and quadratic light elements is presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The variability of the star was found by Miller (1965), using the moments of brightness on 88 photographic plates, it has defined elements of light variation and has noted, that the period of cepheid quickly changes. The star was thoroughly investigated by L. Berdnikov (1987Berdnikov ( , 1992, L. Berdnikov et al (2019), as the cepheid that crosses the instability strip for the first time. It was reported as a Cepheid with Li over-abundance by Luck & Lambert (2011).…”

Section: Introductionmentioning

confidence: 99%

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Lithium-Rich Classical Cepheid V1033 Cyg: Evolutionary Status

Udovichenko

Kovtyukh

Keir

2019

OAP

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lithium-Rich Classical Cepheid V1033 Cyg: Evolutionary Status

Udovichenko

Kovtyukh

Keir

2019

OAP

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Atmospheric parameters of Cepheids from flux ratios with ATHOS

Lemasle

Hanke

Storm

et al. 2020

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Context. The effective temperature is a key parameter governing the properties of a star. For stellar chemistry, it has the strongest impact on the accuracy of the abundances derived. Since Cepheids are pulsating stars, determining their effective temperature is more complicated than in the case of nonvariable stars. Aims. We want to provide a new temperature scale for classical Cepheids, with a high precision and full control of the systematics. Methods. Using a data-driven machine learning technique employing observed spectra, and in taking great care to accurately phase single-epoch observations, we tied flux ratios to (label) temperatures derived using the infrared surface brightness method. Results. We identified 143 flux ratios, which allow us to determine the effective temperature with a precision of a few Kelvin and an accuracy better than 150 K, which is in line with the most accurate temperature measures available to date. The method does not require a normalization of the input spectra and provides homogeneous temperatures for low- and high-resolution spectra, even at the lowest signal-to-noise ratios. Due to the lack of a dataset with a sufficient sample size for Small Magellanic Cloud Cepheids, the temperature scale does not extend to Cepheids with [Fe/H] < −0.6 dex. However, it nevertheless provides an exquisite, homogeneous means of characterizing Galactic and Large Magellanic Cloud Cepheids. Conclusions. The temperature scale will be extremely useful in the context of spectroscopic surveys for Milky Way archaeology with the WEAVE and 4MOST spectrographs. It paves the way for highly accurate and precise metallicity estimates, which will allow us to assess the possible metallicity dependence of Cepheids’ period-luminosity relations and, in turn, to improve our measurement of the Hubble constant H0.

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The MAGIC project – II. Discovery of two new Galactic lithium-rich Cepheids

Kovtyukh

Lemasle

Kniazev

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report the discovery of two new lithium-rich Cepheids in the Milky Way (A(Li) ≈ 2.9 dex) among the targets of the MAGIC spectroscopic survey with the Southern African Large Telescope spectrographs. The 6707 Å Li feature is usually not detectable in the atmosphere of Cepheids. Only three Cepheids (two in the Milky Way and one in the Large Magellanic Cloud) had been reported so far with high lithium abundances. We examine the possibility that the Li-rich Cepheids are evolving towards the red giant branch, crossing the instability strip for the first time, as well as other possible scenarios. The two stars are mixed-mode Cepheids pulsating simultaneously in the first and in the second overtone modes. We briefly discuss the possible connection between their unusual chemical composition and their pulsational properties.

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Search for Evolutionary Changes in the Periods of Cepheids: V1033 Cyg, a Classical Cepheid at the First Crossing of the Instability Strip

Cited by 5 publications

References 9 publications

Lithium-Rich Classical Cepheid V1033 Cyg: Evolutionary Status

Lithium-Rich Classical Cepheid V1033 Cyg: Evolutionary Status

Atmospheric parameters of Cepheids from flux ratios with ATHOS

The MAGIC project – II. Discovery of two new Galactic lithium-rich Cepheids

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