KERVELLA , P.

Context: Thanks to its proximity, alpha Centauri is an outstanding target for an imaging search for extrasolar planets. Aims: We searched for faint comoving companions to alpha Cen located at angular distances of a few tens of arcseconds, up to 2-3 arcmin. Methods: We obtained CCD images from the NTT-SUSI2 instrument in the Bessel V, R, I, and...

Astron. & Astrophys., 474, pp. L49-L52 (2007)

Astron. & Astrophys., 453, pp. 1059-1066 (2006)

Astronomy and Astrophysics, 493, pp. 107-114, http://dx.doi.org./10.1051/0004-6361:200810565

For the nearby dwarf star α Cen B (K1 V), we present limb-darkening predictions from a 3D hydrodynamical radiative transfer model of its atmosphere. We first compared the results of this model to a standard Kurucz's atmosphere. Then we used both predictions to fit the new interferometric visibility measurements of α Cen B obtained with the...

For the nearby dwarf star α Cen B (K1 V), we present limb-darkening predictions from a 3D hydrodynamical radiative transfer model of its atmosphere. We first compared the results of this model to a standard Kurucz's atmosphere. Then we used both predictions to fit the new interferometric visibility measurements of α Cen B obtained with the...

Astronomy and Astrophysics, v. 457, n. 2, p. 575-579, 2006. http://dx.doi.org/10.1051/0004-6361:20065299

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Long baseline interferometry is now able to resolve the pulsational changes of the angular diameters of a significant number of Cepheids in the solar neighborhood. This allows us to apply a new version of the Baade-Wesselink method to measure their distances, for which we do not need to estimate the star?s temperature. Using this method and...

The recent VINCI/VLTI observations presented in Paper I have nearly doubled the total number of available angular diameter measurements of Cepheids. Taking advantage of the significantly larger color range covered by these observations, we derive in the present paper high precision calibrations of the surface brightness-color relations using...

Our team has obtained observations of the photosphere of the two closest red supergiant stars Betelgeuse (α Ori) and Antares (α Sco) using near infrared interferometry. We have been monitoring the photosphere of Betelgeuse with the VLTI/PIONIER instrument for three years. On Antares, we obtained an unprecedented sampling of the visibility...

Astronomy and Astrophysics, 459, pp. 669-678, http://dx.doi.org./10.1051/0004-6361:5966

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...

International audience

Astronomy and Astrophysics, v. 453, p. 309-319, 2006. http://dx.doi.org/10.1051/0004-6361:20054333

Context. Fast rotation is responsible for important changes in the structure and evolution of stars and the way we see them. Optical long baseline interferometry now allows for the study of its effects on the stellar surface, mainly gravity darkening and flattening.Aims. We aim to determine the fundamental parameters of the fast-rotating star...

International audience

Astronomy and Astrophysics, v. 416, p. 941-953, 2004. http://dx.doi.org/10.1051/0004-6361:20031743

Astronomy and Astrophysics, v. 423, p. 327-333, 2004. http://dx.doi.org/10.1051/0004-6361:20035596

Astronomy and Astrophysics, v. 428, p. 131-137, 2004. http://dx.doi.org/10.1051/0004-6361:20041419

Memorie della Societa Astronomica Italiana Supplement, 77, p. 411 (2006)

Astronomy and Astrophysics, 436, pp. 253-262, http://dx.doi.org./10.1051/0004-6361:20042075

Context. The Baade-Wesselink (BW) method, which combines linear and angular diameter variations, is the most common method to determine the distances to pulsating stars. However, the projection factor, p-factor, used to convert radial velocities into pulsation velocities, is still poorly calibrated. This parameter is critical on the use of this...