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The cross correlation method (hereafter CC) is widely used to derive the radial velocity curve of Cepheids when the signal to noise of the spectra is low. However, if it is used with the wrong projection factor, it might introduce some…

Solar and Stellar Astrophysics · Physics 2015-05-13 N. Nardetto , W. Gieren , P. Kervella , P. Fouque , J. Storm , G. Pietrzynski , D. Mourard , D. Queloz

Galactic Cepheids in the vicinity of the Sun have a residual line-of-sight velocity, or gamma-velocity, which shows a systematic blueshift of about 2 km/s compared to an axisymmetric rotation model of the Milky Way. This term is either…

Astrophysics · Physics 2009-11-13 N. Nardetto , A. Stoekl , D. Bersier , T. G. Barnes

In 2005, interferometric observations with VLTI/VINCI and CHARA/FLUOR revealed the existence of a circumstellar envelope (CSE) around some Cepheids. This surrounding material is particularly interesting for two reasons: it could have an…

Solar and Stellar Astrophysics · Physics 2011-12-26 Alexandre Gallenne

The projection factor is a key quantity for the interferometric Baade-Wesselink (hereafter IBW) and surface-brightness (hereafter SB) methods of determining the distance of Cepheids. Indeed, it allows a consistent combination of angular and…

Astrophysics · Physics 2009-06-23 N. Nardetto , D. Mourard , Ph. Mathias , A. Fokin , D. Gillet

Type II Cepheids are old pulsating stars that can be used to trace the distribution of an old stellar population and to measure distances to globular clusters and galaxies within several megaparsecs. One method that can be used to measure…

Accurate radial velocities ($v_{\rm rad}$) of Cepheids are mandatory within the context of distance measurements via the Baade-Wesselink technique. The most common $v_{\rm rad}$ derivation method consists in cross-correlating the observed…

[Abridged] I report the discovery of modulations in radial velocity (RV) curves of four Galactic classical Cepheids and investigate their impact as a systematic uncertainty for Baade-Wesselink distances. Highly precise Doppler measurements…

Solar and Stellar Astrophysics · Physics 2014-06-11 Richard I. Anderson

We provided accurate estimates of distances, radii and iron abundances for four metal-rich Cepheids, namely V340 Ara, UZ Sct, AV Sgr and VY Sgr. The main aim of this investigation is to constrain their pulsation properties and their…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Pedicelli , B. Lemasle , M. Groenewegen , M. Romaniello , G. Bono , C. D. Laney , P. Francois , R. Buonanno , F. Caputo , J. Lub , J. W. Pel , F. Primas , J. Pritchard

High-resolution spectroscopy of pulsating stars is a powerful tool to study the dynamical structure of their atmosphere. Lines asymmetry is used to derive the center-of-mass velocity of the star, while a direct measurement of the…

Solar and Stellar Astrophysics · Physics 2013-06-03 N. Nardetto , P. Mathias , A. Fokin , E. Chapellier , G. Pietrzynski , W. Gieren , D. Graczyk , D. Mourard

The projection factor (p-factor) is an essential component of the classical Baade-Wesselink (BW) technique, that is commonly used to determine the distances to pulsating stars. It is a multiplicative parameter used to convert radial…

The projection factor p is the key quantity used in the Baade-Wesselink (BW) method for distance determination; it converts radial velocities into pulsation velocities. Several methods are used to determine p, such as geometrical and…

We present new high-resolution (R=40000) spectroscopic observations of 18 bright northern Cepheids carried out at David Dunlap Observatory, in 1997. The measurements mainly extend those of presented in Paper I adding three more stars (AW…

Astrophysics · Physics 2009-10-31 L. L. Kiss , J. Vinko

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…

Solar and Stellar Astrophysics · Physics 2015-05-20 R. Molinaro , V. Ripepi , M. Marconi , G. Bono , J. Lub , S. Pedicelli , J. W. Pel

I concisely review the history, applications, and recent developments pertaining to radial velocity (RV) observations of classical pulsating stars. The focus lies on type-I (classical) Cepheids, although the historical overview and most…

Solar and Stellar Astrophysics · Physics 2018-02-09 Richard I. Anderson

I report on the recent discovery of modulation in the radial velocity curves in four classical Cepheids. This discovery may enable significant improvements in the accuracy of Baade-Wesselink distances by revealing a not previously…

Solar and Stellar Astrophysics · Physics 2015-06-22 Richard I. Anderson

The determination of pulsation velocities from observed spectra of Cepheids is needed for the Baade-Wesselink calibration of these primary distance markers. The applicability of the Fourier-disentangling technique for the determination of…

Solar and Stellar Astrophysics · Physics 2015-05-14 P. Hadrava , M. Slechta , P. Skoda

Context. One challenge for measuring the Hubble constant using Classical Cepheids is the calibration of the Leavitt Law or period-luminosity relationship. The Baade-Wesselink method for distance determination to Cepheids relies on the ratio…

Solar and Stellar Astrophysics · Physics 2015-06-04 Hilding R. Neilson , Nicolas Nardetto , Chow-Choong Ngeow , Pascal Fouque , Jesper Storm

The projection factor (p), which converts the radial velocity to pulsational velocity, is an important parameter in the Baade-Wesselink (BW) type analysis and distance scale work. The p-factor is either adopted as a constant or linearly…

Solar and Stellar Astrophysics · Physics 2015-06-05 Chow-Choong Ngeow , Hilding R. Neilson , Nicolas Nardetto , Massimo Marengo

Long baseline interferometry is now able to resolve the pulsational change of the angular diameter of a significant number of Cepheids in the solar neighborhood. This allows the application of a new version of the Baade-Wesselink (BW)…

Astrophysics · Physics 2010-12-09 Pierre Kervella

Anomalous Cepheids are radially pulsating stars observed in dwarf galaxies, the Galactic bulge and halo, and globular clusters. Similarly to other radially pulsating stars, they can be used as distance indicators through their…

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