A5085514816- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Spectroscopy and Laser Applications
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Space Exploration and Technology
- Atmospheric Ozone and Climate
- History and Developments in Astronomy
- Planetary Science and Exploration
- Astrophysics and Cosmic Phenomena
- Calibration and Measurement Techniques
- Methane Hydrates and Related Phenomena
- Advanced Semiconductor Detectors and Materials
- Molecular Spectroscopy and Structure
- Infrared Target Detection Methodologies
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Ionosphere and magnetosphere dynamics
- Aeolian processes and effects
- Spacecraft and Cryogenic Technologies
Observatoire de Paris
2005-2022
Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères
2011-2022
Centre National de la Recherche Scientifique
2009-2021
Université Paris Sciences et Lettres
2018-2021
Sorbonne Université
2007-2019
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2007
Université de Versailles Saint-Quentin-en-Yvelines
2007
Université Paris Cité
2007
KU Leuven
1999
We present a self–consistent time–dependent model for the oxygen–rich Mira variable IRC –20197. This includes consistent treatment of interactions among hydrodynamics, thermodynamics, radiative transfer, equilibrium chemistry, and heterogeneous dust formation with TiO2 nuclei. The is determined by stellar parameters, mass , luminosity temperature solar abundances elements. pulsation star simulated piston at inner boundary where velocity varies sinusoidally period an amplitude . Based on...
We have compiled the near infrared Point Source Catalogue (PSC) towards Magellanic Clouds (MCs) extracted from data obtained with Deep Near Infrared Survey of Southern Sky – DENIS (Epchtein et al. 1997). The catalogue covers an area square degrees centered on , for Large Cloud (LMC) and Small (SMC) at epoch J2000. It contains about sources LMC SMC each detected in least 2 3 photometric bands involved survey (I, J, Ks). are true members Clouds, respectively consist mainly red giants,...
We present the first results of a CO(2–1), (1–0), and 86 GHz SiO maser survey AGB stars, selected by their weak near-infrared excess. Among 65 sources sample we find 10 objects with low CO outflow velocities, km s-1. Typically, these show (much) wider features. Additionally, get 5 composite line profiles, i.e. narrow feature is superimposed on broader one, where both components are centered at same stellar velocity. The gas mass-loss rates, velocities velocity structures suggested profiles...
An absolute calibration of the DENIS photometric system is presented. It includes determination overall transmission profiles in 3 bands, namely i, J and Ks, combining contributions from atmosphere, telescope mirrors, instrument lenses dichroics, filters, detectors. From these normalized profiles, isophotal effective wavelengths are computed, using same synthetic Vega spectrum as that used to support many other ground-based spaceborne systems. Flux densities at zero magnitude derived...
We report the detection of H i line at 21 cm in direction α Orionis (α Ori) with Nançay Radiotelescope and Very Large Array. The observations confirm previous emission centred on Ori, but additionally reveal for first time a quasi-stationary detached shell neutral atomic hydrogen ∼4 arcmin diameter (0.24 pc distance 200 pc). appears elongated opposite to star’s space motion. A simple model shows that this gas can result from collision stellar wind Ori local interstellar medium (ISM). It...
We report the detection of an HI counterpart to extended, far-ultraviolet-emitting tail associated with asymptotic giant branch star Mira (o Ceti). Using Nancay Radio Telescope (NRT), we have detected emission as far 88' north star, confirming that contains a significant atomic component (M_HI ~ 4x10e-3 M_sun). The NRT spectra reveal deceleration gas caused by interaction local interstellar medium. estimate age for ~1.2x10e5 years, suggesting mass-loss history has been more prolonged than...
We are using the 2002 data-release from Japanese space experiment IRTS to investigate spatial distribution of galactic mass-losing (> yr-1) AGB stars and relative contribution C-rich O-rich ones replenishment ISM. Our sample contains 126 563 sources which sorted on basis molecular bands observed in range 1.4–4.0 μm, for we estimate distances mass loss rates near-infrared photometry (K L'). There is a clear dependence galactocentric distance, with outnumbering kpc, reverse kpc. The ISM by...
Red supergiant stars are surrounded by a gaseous and dusty circumstellar environment created their mass loss, which spreads heavy elements into the interstellar medium. The structure dynamics of this envelope crucial to understand processes driving red loss shaping pre-supernova ejecta. We have observed emission from CO J = 2 − 1 line star |$\mu$| Cep with NOEMA interferometer. In synthesized beam was 0.92 × 0.72 arcsec (590 462 au at 641 pc). continuum map shows only unresolved contribution...
Context.CO rotational lines are frequently used to trace the outflows from AGB stars. Some profiles composite, with a narrow component super-imposed on broader one. These have been interpreted in different ways, calling for episodic mass loss, bipolar flow, or circumstellar disk.
Y CVn is a carbon star surrounded by detached dust shell that has been imaged the Infrared Space Observatory at 90 μm. With Nançay Radio Telescope, we have studied gaseous counterpart in 21-cm H i emission line. New data acquired and allow to improve signal-to-noise ratio on this The high spectral resolution line profiles obtained position of several offset positions set strong constraints gas temperature kinematics within shell; bulk material should be ∼100–200 K expansion ∼1−2 km s−1. In...
AGB mass-losing sources are easy to identify and characterize in the near-infrared range (1-5 μm). We make use of data acquired by Japanese space experiment IRTS study a sample detected 2 celestial strips surveyed IRTS. Mass-loss rates distances estimated for 40 carbon-rich 86 oxygen-rich which 8 probably S-type. Although is small, one sees dependence relative contribution two kinds replenishment interstellar medium (ISM) on galactocentric distance. E.g. from 6 kpc, our contribute 10-12...
Recent hydrodynamical models (Winters et al. 2000b) allow the existence of pulsating, large velocity amplitude Asymptotic Giant Branch (AGB) stars with tenuous dusty circumstellar shells, which produce low mass-loss rates and simultaneously wind velocities. The Semi-regular long-period variable L2 Pup shows a broad SiO maser feature at 86 GHz (, ), indicating an outward material close to stellar photosphere least 10 km s-1 , narrow CO () (1-0) line profiles outflow in shell only about 3 ....
This paper presents interferometric and single-dish CO observations along with HI data obtained for the oxygen-rich semi-regular variable RS Cnc, in order to probe its circumstellar environment at different scales. With Plateau de Bure Interferometer IRAM 30-m telescope, we detect both CO(1-0) CO(2-1) rotational lines from Cnc. The line profiles are composite, two components of half-width ~2 km/s ~8 respectively. Whereas narrow velocity component seems originate an equatorial disk central...
The CO(1−0) and (2−1) emission of the circumstellar envelope asymptotic giant branch (AGB) star EP Aqr has been observed in 2003 using IRAM Plateau-de-Bure Interferometer 2004 with 30-m telescope at Pico Veleta. line profiles reveal presence two distinct components centred on velocity, a broad component extending up to ~10 km s-1 narrow indicating an expansion velocity only ~2 s-1. An early analysis these data was performed under assumption isotropic winds. present study revisits this...
We present an imaging study of a sample eight asymptotic giant branch (AGB) stars in the HI 21-cm line. Using observations from Very Large Array, we have unambiguously detected emission associated with extended circumstellar envelopes six targets. The masses range M_HI ~ 0.015-0.055 M_sun. morphologies and kinematics are diverse, but all cases appear to be significantly influenced by interaction between envelope surrounding medium. Four (RX Lep, Y UMa, CVn, V1942 Sgr) surrounded detached...
We have used the Robert C. Byrd Green Bank Telescope to perform most sensitive search date for neutral atomic hydrogen (H i) in circumstellar envelope (CSE) of carbon star IRC+10216. Our observations uncovered a low surface brightness H i shell diameter ∼1300 arcsec (∼0.8 pc), centred on The has an angular extent comparable far ultraviolet-emitting astrosphere IRC+10216 previously detected with GALEX satellite, and its kinematics are consistent matter that been decelerated by local...
The H I line at 21 cm has been detected in the circumstellar shells of two semi-regular variables, EP Aqr and Y CVn, with Nançay Radio-Telescope (NRT). In both cases shape is composite emission spatially extended compared to NRT beam size (4´). total masses envelopes are respectively ~0.047 0.044 . For Aqr, we find three components: a narrow one centered on star unresolved, broad, Gaussian components, offset w.r.t. extended. component traces present wind from whereas others seem trace or...
We present a detailed study of the circumstellar gas distribution and kinematics semi-regular variable star RS Cnc on spatial scales ranging from ~1" (~150 AU) to ~6' (~0.25 pc). New modeling CO1-0 CO2-1 imaging observations leads revised characterization Cnc's previously identified axisymmetric molecular outflow. Rather than simple disk-outflow picture, we find that gradient in velocity as function latitude is needed fit spatially resolved spectra, our preferred model, density vary smoothly...
New observations are presented of millimetre line emissions the circumstellar envelope (CSE) asymptotic giant branch (AGB) star chi Cygni, using recently upgraded NOEMA array. Cygni is an S-type Mira variable, at border between oxygen-rich and carbon-rich stars. It has been observed for over 40 years to display features that suggest evidence strong role played by pulsation-associated shock waves in generation its wind. These new provide a bright H12CN(3-2) emission confined very close...
We report the detection of HI line at 21 cm from circumstellar shell around AGB star X Her using position-switching technique with Nancay Radio Telescope. At position shows 2 components: (i) a broad one (FWHM ~ 13 km/s) centered -72.2 km/s, and (ii) narrow \~ 4 -70.6 km/s. Our map that source associated to component is asymmetric material flowing preferentially towards North-East. This extends 10 arcmin. (~ 0.4 pc) in direction. On other hand, detected only indicates away observer. The total...
Abstract PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions are known exceptional astronomy. The seeing (above ∼30 m height), coherence time, and isoplanatic angle all twice as good typical mid-latitude sites, while water-vapour column, atmosphere thermal emission order of magnitude better. These conditions enable unique scientific capability PILOT, which addressed in...
Context. Circumstellar shells around AGB stars are built over long periods of time that may reach several million years. They therefore be extended large sizes (~1 pc, possibly more), and different complementary tracers needed to describe their global properties.