Improvement of the CORS method for Cepheids radii determination based on Strömgren photometry

Ruoppo, A.; Ripepi, V.; Marconi, M.; Russo, G.

doi:10.1051/0004-6361:20035901

Cited by 10 publications

(26 citation statements)

References 39 publications

(55 reference statements)

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“…Given this overall uncertainty, we decided to use two different values of the p factor: 1.36 and 1.27. These two values were chosen because they include the range of values found in the literature and, in particular, the value 1.36 was selected to allow comparison with our previous works (Ripepi et al 1997; Ruoppo et al 2004).…”

Section: Derivation Of the Radius Of Cepheidsmentioning

confidence: 99%

“…In a previous paper (Ruoppo et al 2004), we adapted the CORS method to derive Cepheid radii observed in the Strömgren system. However, the model atmospheres adopted in the quoted investigation to estimate the surface brightness did not allow us to include Cepheids with periods longer than 12–13 d. The cut‐off in the long‐period range limited the accuracy of the period–radius relation.…”

Section: Introductionmentioning

confidence: 99%

“…In this investigation, we show that this new calibration of the VBLUW Cepheid time series data by Pedicelli et al (2009) allows us to derive precise stellar parameters (surface gravity and effective temperature) at fixed chemical composition and to calibrate with high accuracy the surface brightness function, a fundamental ingredient for the application of the Baade–Wesselink method. This opportunity stimulated us to apply the CORS version of the Baade–Wesselink technique as formulated by Onnembo et al (1985) and Ruoppo et al (2004), to derive reliable radii for a sample of Cepheids having periods from a few days up to ∼40 d and to obtain more accurate period–radius and period–luminosity relations.…”

Section: Introductionmentioning

confidence: 99%

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CORS Baade-Wesselink method in the Walraven photometric system: the period-radius and the period-luminosity relation of classical Cepheids

Molinaro¹,

Ripepi²,

Marconi³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We present a new derivation of the CORS Baade–Wesselink method in the Walraven photometric system. We solved the complete Baade–Wesselink equation by calibrating the surface brightness function with a recent grid of atmosphere models. The new approach was adopted to estimate the mean radii of a sample of Galactic Cepheids for which are available precise light curves in the Walraven bands. Current radii agree, within the errors, quite well with Cepheid radii based on recent optical and near‐infrared interferometric measurements. We also tested the impact of the projection factor on the period–radius relation using two different values (p= 1.36, 1.27) that bracket the estimates available in the literature. We found that the agreement of our period–radius relation with similar empirical and theoretical period–radius relations in the recent literature improves by changing the projection factor from p= 1.36 to 1.27. Our period–radius relation is log R= (0.75 ± 0.03)log P+ (1.10 ± 0.03), with an rms = 0.03 dex. Thanks to accurate estimates of the effective temperature of the selected Cepheids, we also derived the period–luminosity relation in the V band and we found MV= (−2.78 ± 0.11)log P+ (−1.42 ± 0.11) with rms = 0.13 mag, for p= 1.27. It agrees quite well with recent results in the literature, while the relation for p= 1.36 deviates by more than 2σ. We conclude that, even taking into account the intrinsic dispersion of the obtained period–luminosity relations that is roughly of the same order of magnitude as the effect of the projection factor, the results of this paper seem to favour the value p= 1.27.

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Section: Derivation Of the Radius Of Cepheidsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CORS Baade-Wesselink method in the Walraven photometric system: the period-radius and the period-luminosity relation of classical Cepheids

Molinaro¹,

Ripepi²,

Marconi³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…In the present work, we face the problem of the LMC distance by means of the CORS version of the Baade-Wesselink surface brightness technique (Caccin et al 1981;Ripepi et al 1997Ripepi et al , 2000Ruoppo et al 2004;Molinaro et al 2011), using recent photometric and spectroscopic data of a sample of Cepheids observed in the populous cluster NGC 1866. This object is one of the few young (∼10 8 yr; Brocato et al 1989) LMC clusters that are close enough to allow for detailed observation of individual stars (see, e.g., Mucciarelli et al 2011;Brocato et al 2003, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Cors Baade–wesselink Distance to the LMC NGC 1866 Blue Populous Cluster

Molinaro¹,

Ripepi²,

Marconi³

et al. 2012

ApJ

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We used optical, near-infrared photometry, and radial velocity data for a sample of 11 Cepheids belonging to the young LMC blue populous cluster NGC 1866 to estimate their radii and distances on the basis of the CORS Baade-Wesselink method. This technique, based on an accurate calibration of surface brightness as a function of (U − B), (V − K) colors, allows us to estimate, simultaneously, the linear radius and the angular diameter of Cepheid variables, and consequently to derive their distance. A rigorous error estimate on radii and distances was derived by using Monte Carlo simulations. Our analysis gives a distance modulus for NGC 1866 of 18.51 ± 0.03 mag, which is in agreement with several independent results.

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“…Synthetic RV curves for Cepheids have been calculated from new pulsation models by Petroni et al (2003) and Ruoppo et al (2004). Biazzo et al (2004) elaborated a method for measuring simultaneously the temperature and radial velocity of Cepheids from line-depth ratio.…”

Section: Classical Pulsators (Cepheids Rr Lyrae Type Variables)mentioning

confidence: 99%

COMMISSION 30: Radial Velocities

Nordström¹,

Udry²,

Dravins³

et al. 2005

Proc. IAU

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This report from Commission 30 covers the salient areas in which major progress has been made in the triennium covered by the present volume. The principal scientific areas are: The Milky Way, star clusters, spectroscopic binaries, extrasolar planets, pulsating stars and stellar oscillations. Following these, an account is given of the progress in techniques and methodology for radial velocity determinations. Finally, a summary is given of the progress made by the working groups of the Commission, followed by a list of key papers in the triennium. A more extensive report also covering extragalactic work, which due to unforeseen circumstances could not be included here, can be found at the web page of Commission 30 (http://www.iau.org/IAU/Organization/divcom/).

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Improvement of the CORS method for Cepheids radii determination based on Strömgren photometry

Cited by 10 publications

References 39 publications

CORS Baade-Wesselink method in the Walraven photometric system: the period-radius and the period-luminosity relation of classical Cepheids

CORS Baade-Wesselink method in the Walraven photometric system: the period-radius and the period-luminosity relation of classical Cepheids

Cors Baade–wesselink Distance to the LMC NGC 1866 Blue Populous Cluster

COMMISSION 30: Radial Velocities

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