Xavier Delfosse

On the correlation between Ca and Halpha solar emission and consequences for stellar activity observations (2009)

Meunier, Nadege, Delfosse, Xavier

The correlation between Ca and Halpha chromospheric emission, known to be positive in the solar case, has been found to vary between -1 and 1 for other stars. Our objective is to understand the...

Photometric and spectroscopic detection of the primary transit of the 111-day-period planet HD 80606 b (2009)

Moutou, Claire, Hebrard, Guillaume, Bouchy, Francois, Eggenberger, Anne, Boisse, Isabelle, Bonfils, Xavier, ...

We report the detection of the primary transit of the extra-solar planet HD 80606 b, thanks to photometric and spectroscopic observations performed at Observatoire de Haute-Provence, simultaneously...

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results (2008)

Delorme, Philippe, Willott, Chris J., Forveille, Thierry, Delfosse, Xavier, Reylé, Céline, Bertin, Emmanuel, ...

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to...

CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition? (2008)

Delorme, Philippe, Delfosse, Xavier, Albert, Loic, Artigau, Etienne., Forveille, Thierry, Reylé, Céline, ...

We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf identified to date. We found CFBDS0059 using i' and z' images from the Canada-France-Hawaii...

CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition? (2008)

Delorme, Philippe, Delfosse, Xavier, Albert, Loic, Artigau, Etienne., Forveille, Thierry, Reylé, Céline, ...

We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf identified to date. We found CFBDS0059 using i' and z' images from the Canada-France-Hawaii...

CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition? (2008)

Delorme, Philippe, Delfosse, Xavier, Albert, Loic, Artigau, Etienne., Forveille, Thierry, Reylé, Céline, ...

We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf identified to date. We found CFBDS0059 using i' and z' images from the Canada-France-Hawaii...

CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition? (2008)

Delorme, Philippe, Delfosse, Xavier, Albert, Loic, Artigau, Etienne., Forveille, Thierry, Reylé, Céline, ...

We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf identified to date. We found CFBDS0059 using i' and z' images from the Canada-France-Hawaii...

CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition? (2008)

Delorme, Philippe, Delfosse, Xavier, Albert, Loic, Artigau, Etienne., Forveille, Thierry, Reylé, Céline, ...

We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf identified to date. We found CFBDS0059 using i' and z' images from the Canada-France-Hawaii...

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results (2008)

Delorme, Philippe, Willott, Chris, Forveille, Thierry, Delfosse, Xavier, Reylé, Céline, Bertin, Emmanuel, ...

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to...

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results (2008)

Delorme, Philippe, Willott, Chris, Forveille, Thierry, Delfosse, Xavier, Reylé, Céline, Bertin, Emmanuel, ...

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to...

Dynamical evolution of the Gliese 581 planetary system (2007)

Beust, Hervé, Bonfils, Xavier, Delfosse, Xavier, Udry, Stephane

We address the issue of the dynamical evolution of the Gliese 581 planetary system. It is crucial when considering the planets' habitability because the secular evolution of the orbits may regulate...

Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey (2007)

Willott, Chris J., Delorme, Philippe, Omont, Alain, Bergeron, Jacqueline, Delfosse, Xavier, Forveille, Thierry, ...

The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars...

The Large-Scale Axisymmetric Magnetic Topology of a Very-Low-Mass Fully Convective Star (2007)

Donati, Jean-François, Forveille, Thierry, Cameron, Andrew Collier, Barnes, John R., Delfosse, Xavier, Jardine, Moira M., ...

Understanding how cool stars produce magnetic fields within their interiors is crucial for predicting the impact of such fields, such as the activity cycle of the Sun. In this respect, studying fully...

Dynamical evolution of the Gliese 581 planetary system (2007)

Beust, Hervé, Bonfils, Xavier, Delfosse, Xavier, Udry, Stephane

We address the issue of the dynamical evolution of the Gliese 581 planetary system. It is crucial when considering the planets' habitability because the secular evolution of the orbits may regulate...

Dynamical evolution of the Gliese 581 planetary system (2007)

Beust, Hervé, Bonfils, Xavier, Delfosse, Xavier, Udry, Stephane

We address the issue of the dynamical evolution of the Gliese 581 planetary system. It is crucial when considering the planets' habitability because the secular evolution of the orbits may regulate...

First results from the Canada-France High-z Quasar Survey: Constraints on the z=6 quasar luminosity function and the quasar contribution to reionization (2005)

Willott, Chris J., Delfosse, Xavier, Forveille, Thierry, Delorme, Philippe, Gwyn, Stephen D. J.

We present preliminary results of a new quasar survey being undertaken with multi-colour optical imaging from the Canada-France-Hawaii Telescope. The current data consists of 3.83 sq. deg. of imaging...

The pre-main sequence spectroscopic binary UZ Tau East: improved orbital parameters and accretion phase dependence (2004)

Martín, Eduardo L., Magazzù, Antonio, Delfosse, Xavier, Mathieu, Robert D.

We present radial-velocity measurements obtained using high- and intermediate-resolution spectroscopic observations of the classical T Tauri star UZ Tau East obtained from 1994 to 1996. We also...

Spectroscopic identification of DENIS-selected brown dwarf candidates in the Upper Scorpius OB association (2003)

Martin, Eduardo L., Delfosse, Xavier, Guieu, Sylvain

We present low-resolution (R=900) optical (576.1--1,051.1 nm) spectroscopic observations of 40 candidate very low-mass members in the Upper Scorpius OB association. These objects were selected using...

Multiplicity of Nearby Free-floating Ultra-cool Dwarfs: a HST-WFPC2 search for companions (2003)

Bouy, Herve, Brandner, Wolfgang, Martin, Eduardo L., Delfosse, Xavier, Allard, France, Basri, Gibor

We present HST/WFPC2 observations of a sample of 134 ultra-cool objects (spectral types later than M7) coming from the DENIS, 2MASS and SDSS surveys, with distances estimated to range from 7 pc to...

Multiplicity of nearby free-floating ultracool dwarfs: A Hubble Space Telescope WFPC2 search for companions (2003)

Bouy, Hervé, Brandner, Wolfgang, Martín, Eduardo L., Delfosse, Xavier, Allard, France, Basri, Gibor

We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of a sample of 134 ultracool objects (spectral types later than M7) coming from the Deep Near Infrared...

Optical Linear Polarimetry of Ultra Cool Dwarfs (2002)

Menard, Francois, Delfosse, Xavier, Monin, Jean-Louis

Optical linear polarimetry of 8 ultra cool field dwarfs, with spectral types ranging from M9 to L8, is presented. The linear polarisation, P, of each dwarf we measured is P < 0.2%. Three dwarfs have...

An Effective Temperature Scale for Late M and L Dwarfs, from Resonance Absorption Lines of CsI and RbI (2000)

Basri, Gibor, Mohanty, Subhanjoy, Allard, France, Hauschildt, Peter H., Delfosse, Xavier, Martin, Eduardo L., ...

We present Keck HIRES spectra of 6 late-M dwarfs and 11 L dwarfs. Our goal is to assign effective temperatures to the objects using detailed atmospheric models and fine analysis of the alkali...

Accurate masses of very low mass stars: I Gl 570BC (0.6+0.4 Msol) (1999)

Forveille, Thierry, Beuzit, Jean Luc, Delfosse, Xavier, Segransan, Damien, Beck, Francoise, Mayor, Michel, ...

We present very accurate individual masses (1.2% relative accuracy) for the two components of Gl 570BC, an interferometric and double-lined spectroscopic binary system. They were obtained from new...

The closest extrasolar planet: A giant planet around the M4 dwarf Gl 876 (1998)

Delfosse, Xavier, Forveille, Thierry, Mayor, Michel, Perrier, Christian, Naef, Dominique, Queloz, Didier

High precision radial velocity observations of the nearby M4 dwarf Gl 876 with the Observatoire de Haute Provence 1.93 m telescope and the new 1.20 m swiss telescope at la Silla indicate the presence...