A5043902535- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- History and Developments in Astronomy
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Molecular Spectroscopy and Structure
- Galaxies: Formation, Evolution, Phenomena
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Geophysics and Gravity Measurements
- Atomic and Molecular Physics
- Spacecraft and Cryogenic Technologies
- Space Exploration and Technology
- Geomagnetism and Paleomagnetism Studies
- Planetary Science and Exploration
- Radio Astronomy Observations and Technology
- Infrared Target Detection Methodologies
Université Grenoble Alpes
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Institut de Planétologie et d'Astrophysique de Grenoble
2015-2024
Observatoire des sciences de l'Univers Paris-Saclay
2007-2021
Observatoire des Sciences de l'Univers de Grenoble
2007-2021
Health Affairs
2019
Université Joseph Fourier
2006-2016
IPAG Business School
2014
Global Social Observatory
2012
Canada–France–Hawaii Telescope
2000-2009
(Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation initial conditions. This drives observations a sample 102 southern nearby M dwarfs, using fraction our guaranteed time on ESO/HARPS spectrograph (Feb. 11th, 2003 to Apr. 1st 2009). paper makes available sample's series, presents their precision and variability. We apply systematic searches diagnostics discriminate whether observed Doppler shifts are caused by stellar surface...
We present discovery imaging and spectroscopy for nine new z ~ 6 quasars found in the Canada-France High-z Quasar Survey (CFHQS) bringing total number of CFHQS to 19. By combining with more luminous SDSS sample we are able derive quasar luminosity function from a 40 at redshifts 5.74 < 6.42. Our binned shows slightly lower normalisation flatter slope than previous work. The data also suggest break M_1450 approx -25. A double power law maximum likelihood fit is consistent results. strongly...
We report the discovery of a medium-strength (∼0.5 kG) magnetic field on young, massive star τ Sco (B0.2 V), which becomes third-hottest known. Circularly polarized Zeeman signatures are clearly detected in observations collected mostly with ESPaDOnS spectropolarimeter, recently installed 3.6-m Canada–France–Hawaii Telescope; temporal variability is also established polarimetry, and can be unambiguously attributed to rotational modulation period close 41 d. Archival ultraviolet (UV) spectra...
We present spectra for 12 new ultracool dwarfs found in the DENIS infrared survey. Seven of them have spectral types at bottom M-class (M8–M9.5), and other five belong to cooler "L" class. also two L by EROS 2 proper-motion introduce a scheme dwarf classification that is based on an extension pseudocontinuum ratio previously defined M dwarfs. For calibrating subclasses, we use temperature scale late-M recently obtained Basri et al. from synthetic spectrum fitting high-resolution profiles Cs...
This Letter reports on the detection of two super-Earth planets in Gl 581 system, which is already known to harbour a hot Neptune. One has mass 5 and resides at "warm" edge habitable zone star. It thus exoplanet that most resembles our own Earth. The other planet 7.7 orbits 0.25 AU from star, close "cold" zone. These new light around an M3 dwarf further confirm formerly tentative statistical trend toward (i) many more very low-mass being found M dwarfs than solar-type stars (ii) outnumbering...
We present in this paper the first results of a spectropolarimetric analysis small sample (~ 20) active stars ranging from spectral type M0 to M8, which are either fully-convective or possess very radiative core. This study aims at providing new constraints on dynamo processes stars. The focuses 5 ~M4, i.e. with masses close full convection threshold 0.35 Msun), and short rotational periods. Tomographic imaging techniques allow us reconstruct surface magnetic topologies rotationally...
Context.Optical long-baseline interferometry is moving a crucial step forward with the advent of general-user scientific instruments that equip large aperture and hectometric baseline facilities, such as Very Large Telescope Interferometer (VLTI).
The GJ 581 planetary system is already known to harbour three planets, including two super-Earth planets that straddle its habitable zone. We report the detection of an additional planet – 581e with a minimum mass 1.9 . With period 3.15 days, it innermost and has ~5% transit probability. also correct our previous confusion about orbital 581d (the outermost planet) one-year alias, benefitting from extended time span many more measurements. revised 66.8 positions semi-major axis inside zone...
We present here additional results of a spectropolarimetric survey small sample stars ranging from spectral type M0 to M8 aimed at investigating observationally how dynamo processes operate in on both sides the full convection threshold (spectral M4). The paper focuses early M (M0--M3), i.e. above threshold. Applying tomographic imaging techniques time series rotationally modulated circularly polarised profiles collected with NARVAL spectropolarimeter, we determine rotation period and...
The isolated, young, sunlike star TW Hya and four other young stars in its vicinity are strong x-ray sources. Their similar optical properties indicate that the make up a physical association is on order of 20 million years old lies between about 40 60 parsecs (between 130 200 light years) from Earth. itself displays circumstellar CO, HCN, CN, HCO + emission. These molecules probably orbit solar-system–sized disk viewed more or less face-on, whereas likely pole-on. Being at least three times...
Aims.In this paper, we present an innovative data reduction method for single-mode interferometry. It has been specifically developed the AMBER instrument, three-beam combiner of Very Large Telescope Interferometer, but it can be derived any interferometer.
Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates searches around stars which are significantly more massive or less than the Sun, and in particular our radial velocity search for planets very-low stars. Methods: As part that program, we obtained measurements GJ 674, an M2.5 dwarf at d=4.5 pc, have dispersion much excess their internal errors. An intensive observing campaign demonstrates due to two superimposed...
We report on the discovery of a substellar companion or massive Jupiter orbiting G5V star HD 16760 using spectrograph <i>SOPHIE<i/> installed OHP 1.93-m telescope. Characteristics and performances are presented, as well exoplanet consortium program. With minimum mass 14.3 , an orbital period 465 days eccentricity 0.067, 16760b seems to be located just at end distribution giant planets, close planet/brown-dwarf transition. Its quite circular orbit supports formation in gaseous protoplanetary disk.
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 discovery first four CFHQS at redshifts greater than 6, including most distant known quasar, J2329-0301 z = 6.43. We describe observational method used identify and optical, infrared, millimeter photometry near-infrared spectroscopy. investigate dust properties these quasars, finding unusual extinction curve for one quasar a high...
<i>Aims. <i/>Extra-solar planet search programs require high-precision velocity measurements. They need to determine how differentiate between radial-velocity variations due Doppler motion and the noise induced by stellar activity.<i>Methods. <i/>We monitored active K2V star HD 189 733 its transiting planetary companion, which has a 2.2-day orbital period. We used high-resolution spectograph <i>SOPHIE<i/> mounted on 1.93-m telescope at Observatoire de Haute-Provence obtain 55 spectra of over...
We present Keck HIRES spectra of 6 late-M dwarfs and 11 L dwarfs. Our goal is to assign effective temperatures the objects using detailed atmospheric models fine analysis alkali resonance absorption lines CsI RbI. These yield mutually consistent results (+-150 K) when we use ``cleared-dust'' models, which account for removal refractory species from molecular states but do not include dust opacities. find a tendency RbI line imply slightly higher temperature, ascribe an incomplete treatment...
Understanding how cool stars produce magnetic fields within their interiors is crucial for predicting the impact of such fields, as activity cycle Sun. In this respect, studying fully convective enables us to investigate role zones in field generation. We produced a map rapidly rotating, very-low-mass, dwarf through tomographic imaging from time series spectropolarimetric data. Our results, which demonstrate that are able trigger axisymmetric large-scale poloidal without differential...
We report the discovery of a Neptune-mass planet around Gl 581 (M3V, ), based on precise Doppler measurements with HARPS spectrograph at La Silla Observatory. The radial velocities reveal circular orbit period P = 5.366 days and semi-amplitude K1 13.2 m s-1. resulting minimum mass () is only 0.052 0.97 16.6 making 581b one lightest extra-solar known to date. planetary system third centered an M dwarf, joining 876 three-planet lone 436. Its reinforces emerging tendency such planets be low...
We obtained high resolution ELODIE and CORALIE spectra for both components of 20 wide visual binaries composed an F-, G- or K-dwarf primary M-dwarf secondary. analyse the well-understood primaries to determine metallicities ([Fe/H]) these systems, hence their M dwarf components. pool with determinations from literature obtain a precise (±0.2 dex) photometric calibration metallicities. This represents breakthrough in field where discussions have had remain largely qualitative, it helps us...