CCD BV I c observations of classical Cepheids in 2013–2014

Бердников, Л. Н.; Kniazev, A. Y.; Sefako, Ramotholo; Дамбис, А. К.; Kravtsov, V. V.; Zhuiko, S. V.

doi:10.1134/s1063773715020012

Cited by 14 publications

(3 citation statements)

References 12 publications

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“…Exemplary O-C diagrams may be found e.g. in studies by Berdnikov & Pastukhova (1994) or Berdnikov et al (1997). A detailed study of OGLE and MACH data for LMC Cepheids was conducted by Poleski (2008) who detected period changes in 41 per cent of 1O LMC Cepheids and in 18 per cent of fundamental mode pulsators.…”

Section: Overviewmentioning

confidence: 99%

Non-radial pulsation in first overtone Cepheids of the Small Magellanic Cloud

Smolec¹,

Śniegowska²

2016

Mon. Not. R. Astron. Soc.

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We analyse photometry for 138 first overtone Cepheids from the Small Magellanic Cloud, in which Optical Gravitational Lensing Experiment (OGLE) team discovered additional variability with period shorter than first overtone period, and period ratios in the P/P 1O ∈ (0.60, 0.65) range. In the Petersen diagram these stars form three well separated sequences. The additional variability cannot correspond to other radial mode. This form of pulsation is still puzzling.We find that amplitude of the additional variability is small, typically 2-4 per cent of the first overtone amplitude, which corresponds to 2-5 mmag. In some stars we find simultaneously two close periodicities corresponding to two sequences in the Petersen diagram. The most important finding is the detection of power excess at half the frequency of the additional variability (at subharmonic) in 35 per cent of the analysed stars. Interestingly, power excess at subharmonic frequency is detected mostly for stars of the middle sequence in the Petersen diagram (74 per cent), incidence rate is much lower for stars of the top sequence (31 per cent), and phenomenon is not detected for stars of the bottom sequence. The amplitude and/or phase of the additional periodicities strongly vary in time.Similar form of pulsation is observed in first overtone RR Lyrae stars. Our results indicate that the nature and cause of this form of pulsation is the same in the two groups of classical pulsators; consequently, a common model explaining this form of pulsation should be searched for. Our results favour the theory of the excitation of non-radial modes of angular degrees 7, 8 and 9, proposed recently by Dziembowski.

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Section: Overviewmentioning

confidence: 99%

Non-radial pulsation in first overtone Cepheids of the Small Magellanic Cloud

Smolec¹,

Śniegowska²

2016

Mon. Not. R. Astron. Soc.

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“…Small zero point differences on the order of hundredths of magnitude are present among different catalogues. They were fixed as follows: when the Johnson 𝐵, 𝑉, 𝐼 photometry by Berdnikov et al (2004Berdnikov et al ( , 2009Berdnikov et al ( , 2011Berdnikov et al ( , 2015 was available, we used these studies as reference (to keep the information on color); in all other cases our reference was the ASAS catalogue.…”

Section: Period and Epoch Of Maximum Light Estimates From Optical Pho...mentioning

confidence: 99%

Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: I. HARPS-N@TNG spectroscopy of 47 Classical Cepheid and 1 BL Her variables

Ripepi,

Catanzaro,

Molinaro

et al. 2021

Preprint

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Classical Cepheids (DCEPs) are the most important primary indicators of the extragalactic distance scale. Establishing the dependence on metallicity of their period-luminosity and period-Wesenheit (𝑃𝐿𝑍/𝑃𝑊 𝑍) relations has deep consequences on the calibration of secondary distance indicators that lead to the final estimate of the Hubble constant (H 0 ). We collected high-resolution spectroscopy for 47 DCEPs plus 1 BL Her variables with HARPS-N@TNG and derived accurate atmospheric parameters, radial velocities and metal abundances. We measured spectral lines for 29 species and characterized their chemical abundances, finding very good agreement with previous results. We re-determined the ephemerides for the program stars and measured their intensity-averaged magnitudes in the 𝑉, 𝐼, 𝐽, 𝐻, 𝐾 𝑠 bands. We complemented our sample with literature data and used the Gaia Early Data Release 3 (EDR3) to investigate the 𝑃𝐿𝑍/𝑃𝑊 𝑍 relations for Galactic DCEPs in a variety of filter combinations. We find that the solution without any metallicity term is ruled out at more than the 5 𝜎 level. Our best estimate for the metallicity dependence of the intercept of the 𝑃𝐿𝐾 𝑠 , 𝑃𝑊 𝐽𝐾 𝑠 , 𝑃𝑊𝑉 𝐾 𝑠 and 𝑃𝑊 𝐻𝑉 𝐼 relations with three parameters, is −0.456±0.099, −0.465±0.071, −0.459±0.107 and −0.366±0.089 mag/dex, respectively. These values are significantly larger than the recent literature. The present data are still inconclusive to establish whether or not also the slope of the relevant relationships depends on metallicity. Applying a correction to the standard zero point offset of the Gaia parallaxes has the same effect of reducing by ∼22% the size of the metallicity dependence on the intercept of the PLZ/PWZ relations.

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“…The optical PL relations, except those in the Gaia photometric systems, primarily used one of the largest compilations of photoelectric observations of 894 Cepheids in standard Johnson-Cousin-Kron filters (U BV(RI)c, Berdnikov 2008) or the modern CCD photometry of Cepheids in BV I bands (e.g. Berdnikov et al 2015). Time-domain variability surveys such as the Optical Gravitational Lensing Experiment (OGLE, Udalski et al 2018) and the All-Sky Automated Survey for Supernovae (ASAS-SN, Jayasinghe et al 2018) have also provided optical V and/or I light curves of thousands of Cepheids in the MW, but lack multiwavelength coverage.…”

Section: Introductionmentioning

confidence: 99%

Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey

Bhardwaj,

Ripepi,

Testa

et al. 2024

A&A

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The highly debated effect of metallicity on the absolute magnitudes of classical Cepheid variables needs to be properly quantified for determining accurate and precise distances based on their Leavitt Law. Our goal is to obtain homogeneous optical and near-infrared light curves of Milky Way Cepheid variables complementing their already collected high-resolution spectroscopic metallicities as part of the C-MetaLL survey. Together with Gaia parallaxes, we investigate period-luminosity-metallicity relations for Cepheid variables at multiple wavelengths. We present homogeneous multiband ($grizJHK_s$) time-series observations of 78 Cepheids including 49 fundamental mode variables and 29 first-overtone mode variables. These observations were collected simultaneously using the ROS2 and REMIR instruments at the Rapid Eye Mount telescope. Multiwavelength photometric data were used to investigate pulsation properties of Cepheid variables and derive their period--luminosity (PL) and period--Wesenheit (PW) relations. The Cepheid sample covers a large range of distances ($0.5-19.7$ kpc) with varying precision of parallaxes, and thus astrometry-based luminosity fits were used to derive PL and PW relations in optical Sloan ($griz$) and near-infrared ($JHK_s$) filters. These empirically calibrated relations exhibit large scatter primarily due to larger uncertainties in parallaxes of distant Cepheids, but their slopes agree well with those previously determined in the literature. Using homogeneous high-resolution spectroscopic metallicities of 61 Cepheids covering $-1.1< Fe/H <0.6$ dex, we quantified the metallicity dependence of PL and PW relations which varies between $-0.30 (in $K_s$) and $-0.55 (in $z$) mag/dex in $grizJHK_s$ bands. However, the metallicity dependence in the residuals of the PL and PW relations is predominantly seen for metal-poor stars ($ Fe/H <-0.3$ dex), which also have larger parallax uncertainties. The modest sample size precludes us from separating the contribution to the residuals due to parallax uncertainties, metallicity effects, and reddening errors. While this Cepheid sample is not optimal for calibrating the Leavitt law, upcoming photometric and spectroscopic datasets of the C-MetaLL survey will allow the accurate derivation of PL and PW relations in the Sloan and near-infrared bandpasses, which will be useful for the distance measurements in the era of the Vera C. Rubin Observatory's Legacy Survey of Space and Time and upcoming extremely large telescopes.

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CCD BV I c observations of classical Cepheids in 2013–2014

Cited by 14 publications

References 12 publications

Non-radial pulsation in first overtone Cepheids of the Small Magellanic Cloud

Non-radial pulsation in first overtone Cepheids of the Small Magellanic Cloud

Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: I. HARPS-N@TNG spectroscopy of 47 Classical Cepheid and 1 BL Her variables

Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey

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