Cepheid distances from the Baade–Wesselink method

Gieren, W.; Storm, J.; Nardetto, N.; Gallenne, A.; Pietrzyński, G.; Fouqué, P.; Barnes, Thomas G.; Majaess, D.

doi:10.1017/s1743921312021266

Cited by 5 publications

(3 citation statements)

References 40 publications

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“…Parallax measurements can be used to determine the zero point of the P-L relationship, but they are reasonably accurate only for a few nearby Cepheids. Other distance estimates, such as the Baade-Wesselink (hereafter BW) technique (Gieren et al 2013) and its infrared surface-brigthness version (Storm et al 2011), the light echoes of RS Pup , or binary Cepheid orbital parallax (Pilecki et al 2013;Gallenne et al 2013Gallenne et al , 2014, should be obtained as independent cross-checks to ensure the accuracy of the calibration. We are currently carrying out a long-term programme of interferometric observations of Cepheids in both hemispheres, using the CHARA array installed at the Mount Wilson Observatory in California (ten Brummelaar et al 2005) and the Very Large Telescope Interferometer (hereafter VLTI) installed at the Cerro Paranal in Chile .…”

Section: Introductionmentioning

confidence: 99%

Observational calibration of the projection factor of Cepheids

Breitfelder

Kervella

Mérand

et al. 2015

A&A

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Context. The distance of pulsating stars, in particular Cepheids, are commonly measured using the parallax of pulsation technique. The different versions of this technique combine measurements of the linear diameter variation (from spectroscopy) and the angular diameter variation (from photometry or interferometry) amplitudes, to retrieve the distance in a quasi-geometrical way. However, the linear diameter amplitude is directly proportional to the projection factor (hereafter p-factor), which is used to convert spectroscopic radial velocities (i.e., disk integrated) into pulsating (i.e., photospheric) velocities. The value of the p-factor and its possible dependence on the pulsation period are still widely debated. Aims. Our goal is to measure an observational value of the p-factor of the type-II Cepheid κ Pavonis. Methods. The parallax of the type-II Cepheid κ Pav was measured with an accuracy of 5% using HST/FGS. We used this parallax as a starting point to derive the p-factor of κ Pav, using the SPIPS technique (Spectro-Photo-Interferometry of Pulsating Stars), which is a robust version of the parallax-of-pulsation method that employs radial velocity, interferometric and photometric data. We applied this technique to a combination of new VLTI/PIONIER optical interferometric angular diameters, new CORALIE and HARPS radial velocities, as well as multi-colour photometry and radial velocities from the literature. Results. We obtain a value of p = 1.26 ± 0.07 for the p-factor of κ Pav. This result agrees with several of the recently derived Periodp-factor relationships from the literature, as well as previous observational determinations for Cepheids. Conclusions. Individual estimates of the p-factor are fundamental to calibrating the parallax of pulsation distances of Cepheids. Together with previous observational estimates, the projection factor we obtain points to a weak dependence of the p-factor on period.

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Section: Introductionmentioning

confidence: 99%

Observational calibration of the projection factor of Cepheids

Breitfelder

Kervella

Mérand

et al. 2015

A&A

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“…1 Concerns regarding spurious cluster Cepheids are warranted, and the calibration is under constant revision. However, those concerns can be mitigated by favoring calibrators exhibiting matching cluster and IRSB 2 distances (Gieren et al 2013), unless overwhelming evidence exists supporting the cluster Cepheids in question (e.g., radial velocities and multiband photometry).…”

Section: Introductionmentioning

confidence: 99%

Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Majaess¹,

Sturch

Bidin

et al. 2013

Astrophys Space Sci

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Cepheids are key to establishing the cosmic distance scale. Therefore it's important to assess the viability of QZ Nor, V340 Nor, and GU Nor as calibrators for Leavitt's law via their purported membership in the open cluster NGC 6067. The following suite of evidence confirms that QZ Nor and V340 Nor are members of NGC 6067, whereas GU Nor likely lies in the foreground: (i) existing radial velocities for QZ Nor and V340 Nor agree with that established for the cluster (−39.4 ± 0.2(σx) ± 1.2(σ) km/s) to within 1 km/s, whereas GU Nor exhibits a markedly smaller value; (ii) a steep velocity-distance gradient characterizes the sight-line toward NGC 6067, thus implying that objects sharing common velocities are nearly equidistant; (iii) a radial profile constructed for NGC 6067 indicates that QZ Nor is within the cluster bounds, despite being 20 ′ from the cluster center; (iv) new BV JH photometry for NGC 6067 confirms the cluster lies d = 1.75 ± 0.10 kpc distant, a result that matches Wesenheit distances computed for QZ Nor/V340 Nor using the Benedict et al. (2007, HST parallaxes) calibration. QZ Nor is a cluster Cepheid that should be employed as a calibrator for the cosmic distance scale.

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“…(1)) matches that derived for LMC and SMC Cepheids (Ngeow et al 2009), but is inconsistent with the slope established for distant solar extragalactic Cepheids associated with known supernova-host galaxies (Majaess 2010;Riess et al 2009). Continued research aimed at reducing uncertainties associated with the Cepheid calibration (e.g., Benedict et al 2007;Gieren et al 2013) and the impact of crowding on remote extragalactic Cepheid photometry may eventually help identify the source behind discrepant values of H 0 cited in the literature (e.g., Riess et al 2011;Freedman et al 2012;Tammann & Reindl 2013;Planck Collaboration 2013).…”

Section: Resultsmentioning

confidence: 99%

Anchors for the cosmic distance scale: the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae

Majaess

Carraro

Bidin

et al. 2013

A&A

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New and existing X-ray, UBV JHK s W (1−4) , and spectroscopic observations were analyzed to constrain fundamental parameters for M 25, NGC 7790, and dust along their sight-lines. The star clusters are of particular importance because they host the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa and CEb Cas. Precise results from the multiband analysis, in tandem with a comprehensive determination of the Cepheids' period evolution (dP/dt) from ∼140 years of observations, helped to resolve concerns raised regarding the clusters and their key Cepheid constituents. Specifically, the distances derived for members of M 25 and NGC 7790 are 630 ± 25 pc and 3.40 ± 0.15 kpc, respectively.

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Cepheid distances from the Baade–Wesselink method

Cited by 5 publications

References 40 publications

Observational calibration of the projection factor of Cepheids

Observational calibration of the projection factor of Cepheids

Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Anchors for the cosmic distance scale: the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae

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