Cepheid distances from infrared long-baseline interferometry

Kervella, P.; Bersier, D.; Mourard, D.; Nardetto, N.; Fouqué, P.; Foresto, V. Coudé du

doi:10.1051/0004-6361:20041416

Cited by 119 publications

(139 citation statements)

References 34 publications

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“…The photosphere's angular size θ , used to calculate the area of the object in the sky, is also an indicator of R ph /D. For Galactic cool giants, supergiants, and Cepheid variables, a relation is found between the surface brightness and a suitably chosen color index, which can be used as a proxy for temperature (Welch 1994;Fouqué & Gieren 1997;Kervella et al 2004a). In the case of SNe II, atmosphere models show that the emergent flux, which depends on many parameters (e.g., chemical composition or density structure of the progenitor star), has an important dependence on temperature and, in shortwavelength bandpasses, density at the photosphere (Eastman et al 1996).…”

Section: Surface Brightness Methodsmentioning

confidence: 99%

Photospheric Magnitude Diagrams for Type Ii Supernovae: A Promising Tool to Compute Distances

Rodríguez

Clocchiatti

Hamuy

2014

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We develop an empirical color-based standardization for Type II supernovae (SNe II), equivalent to the classical surface brightness method given in Wesselink. We calibrate this standardization using SNe II with host galaxy distances measured using Cepheids, and a well-constrained shock breakout epoch and extinction due to the host galaxy. We estimate the reddening with an analysis of the B −V versus V −I color-color curves, similar to that of Natali et al. With four SNe II meeting the above requirements, we build a photospheric magnitude versus color diagram (similar to an H-R diagram) with a dispersion of 0.29 mag. We also show that when using time since shock breakout instead of color as the independent variable, the same standardization gives a dispersion of 0.09 mag. Moreover, we show that the above time-based standardization corresponds to the generalization of the standardized candle method of Hamuy & Pinto for various epochs throughout the photospheric phase. To test the new tool, we construct Hubble diagrams for different subsamples of 50 low-redshift (cz < 10 4 km s −1 ) SNe II. For 13 SNe within the Hubble flow (cz CMB > 3000 km s −1 ) and with a well-constrained shock breakout epoch we obtain values of 68-69 km s −1 Mpc −1 for the Hubble constant and a mean intrinsic scatter of 0.12 mag or 6% in relative distances.

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Section: Surface Brightness Methodsmentioning

confidence: 99%

Photospheric Magnitude Diagrams for Type Ii Supernovae: A Promising Tool to Compute Distances

Rodríguez

Clocchiatti

Hamuy

2014

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“…As a test of our calibration, we have analyzed the relation F V = F V (V − K), where F V = 4.2207-0.1S V is the surface brightness parameter. Figure 7 shows the selected Cepheids plotted in the F V -(V − K) plane together with the relation obtained by Kervella et al (2004) using interferometric measurement of nine Galactic Cepheids. The errors for the color (V − K) have been estimated by considering the scatter around the interpolated light curves, as explained in Section 3.1, while those for surface brightness have been estimated by means of simulations, as described in Appendix C. The plot shows a small discrepancy between the fitted relation and the surface brightness of NGC 1866 Cepheids, which seems to be systematically brighter than the expected values from the relation by Kervella et al (2004).…”

Section: The Surface Brightness Calibrationmentioning

confidence: 98%

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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“…For each model atmosphere, intensity profiles are computed for the BVRIH, and K-bands, though for most of this work, discussion is restricted to V and K-band profiles. It is these two wavebands that are used for interferometric observations (Kervella et al 2004;Mourard et al 2009) as well as for the infrared surface brightness technique (Gieren et al 2005;Storm et al 2011a,b).…”

Section: Model Stellar Atmospheresmentioning

confidence: 99%

Cepheid limb darkening, angular diameter corrections, and projection factor from static spherical model stellar atmospheres

Neilson

Nardetto

Ngeow

et al. 2012

A&A

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Context. One challenge for measuring the Hubble constant using classical Cepheids is the calibration of the Leavitt law or periodluminosity relationship. The Baade-Wesselink method for distance determination to Cepheids relies on the ratio of the measured radial velocity and pulsation velocity, the so-called projection factor and the ability to measure the stellar angular diameters. Aims. We use spherically-symmetric model stellar atmospheres to explore the dependence of the p-factor and angular diameter corrections as a function of pulsation period. Methods. Intensity profiles are computed from a grid of plane-parallel and spherically-symmetric model stellar atmospheres using the SAtlas code. Projection factors and angular diameter corrections are determined from these intensity profiles and compared to previous results. Results. Our predicted geometric period-projection factor relation including previously published state-of-the-art hydrodynamical predictions is not with recent observational constraints. We suggest a number of potential resolutions to this discrepancy. The model atmosphere geometry also affects predictions for angular diameter corrections used to interpret interferometric observations, suggesting corrections used in the past underestimated Cepheid angular diameters by 3-5%. Conclusions. While spherically-symmetric hydrostatic model atmospheres cannot resolve differences between projection factors from theory and observations, they do help constrain underlying physics that must be included, including chromospheres and mass loss. The models also predict more physically-based limb-darkening corrections for interferometric observations.

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Cepheid distances from infrared long-baseline interferometry

Cited by 119 publications

References 34 publications

Photospheric Magnitude Diagrams for Type Ii Supernovae: A Promising Tool to Compute Distances

Photospheric Magnitude Diagrams for Type Ii Supernovae: A Promising Tool to Compute Distances

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

Cepheid limb darkening, angular diameter corrections, and projection factor from static spherical model stellar atmospheres

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