# High-resolution spectroscopy for Cepheids distance determination V. Impact of the cross-correlation method on the p-factor and the γ-velocities

@article{Nardetto2009HighresolutionSF, title={High-resolution spectroscopy for Cepheids distance determination V. Impact of the cross-correlation method on the p-factor and the $\gamma$-velocities}, author={Nicolas Nardetto and Wolfgang Gieren and Pierre Kervella and P Fouqu{\'e} and Jesper Storm and G. Pietrzynski and Denis Mourard and Didier Queloz}, journal={Astronomy and Astrophysics}, year={2009}, volume={502}, pages={951-956} }

Context: The cross correlation method (hereafter CC) is widely used to derive the radial velocity curve of Cepheids when the signal to noise ratio of the spectra is low. However, if it is used with an inaccurate projection factor, it might introduce some biases in the Baade-Wesselink (BW) methods of determining the distance of Cepheids. In addition, it might affect the average value of the radial velocity curve (or γ-velocity) important for Galactic structure studies. Aims: We aim to derive a… Expand

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#### References

SHOWING 1-10 OF 15 REFERENCES

High resolution spectroscopy for Cepheids distance determination. I. Line asymmetry

- Physics
- 2006

Context. The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy of the Baade-Wesselink method, and in particular of its interferometric version recently… Expand

High resolution spectroscopy for Cepheids distance determination ⋆ III. A relation between γ-velocities and γ-asymmetries

- Physics
- 2008

Context. Galactic Cepheids in the vicinity of the Sun have a residual line-of-sight velocity, or γ -velocity, which shows a systematic blueshift of about 2 km s -1 compared to an axisymmetric… Expand

Self consistent modelling of the projection factor for interferometric distance determination

- Physics
- 2004

The distance of galactic Cepheids can be derived through the interferometric Baade-Wesselink method. The interfer- ometric measurements lead to angular diameter estimations over the whole pulsation… Expand

The projection factor of δ Cephei A calibration of the Baade-Wesselink method using the CHARA Array

- Physics
- 2005

Cepheids play a key role in astronomy as standard candles for measuring intergalactic distances. Their distance is usually inferred from the period-luminosity relationship, calibrated using the… Expand

A New Calibration Of Galactic Cepheid Period-Luminosity Relations From B To K Bands, And A Comparison To LMC Relations

- Physics
- 2007

Context. The universality of the Cepheid Period-Luminosity relations has been under discussion since metallicity effects have been assumed to play a role in the value of the intercept and, more… Expand

Cepheid Period-Radius and Period-Luminosity Relations and the Distance to the Large Magellanic Cloud

- Physics
- 1998

We have used the infrared Barnes-Evans surface brightness technique to derive the radii and distances of 34 Galactic Cepheid variables. Radius and distance results obtained from both versions of the… Expand

Direct Distances to Cepheids in the Large Magellanic Cloud: Evidence for a Universal Slope of the Period-Luminosity Relation up to Solar Abundance

- Physics
- 2005

We have applied the infrared surface brightness (ISB) technique to derive distances to 13 Cepheid variables in the LMC that span a period range from 3 to 42 days. From the absolute magnitudes of the… Expand

Infrared Spectroscopy of Cepheids. II. Line Profiles from Different Atmospheric Layers

- Physics
- 1990

The first analysis of high-resolution IR spectra at 1.08 and 1.6 microns is presented for classical Cepheid variables. Three of the seven program stars were observed with complete phase coverage. The… Expand

Cepheid distances from infrared long-baseline interferometry - I. VINCI/VLTI observations of seven Galactic Cepheids

- Physics
- 2004

We report the angular diameter measurements of seven classical Cepheids, X Sgr, η Aql, W Sgr, ζ Gem, β Dor, Y Oph andCar that we have obtained with the VINCI instrument, installed at ESO's VLT… Expand

ELODIE: A spectrograph for accurate radial velocity measurements

- Physics
- 1996

The bre{fed echelle spectrograph of Observatoire de Haute{Provence, ELODIE, is presented. This instrument has been in operation since the end of 1993 on the 1.93 m telescope. ELODIE is designed as an… Expand