MILLI , J.

Circumstellar environments are now routinely observed by dedicated high-contrast imagers on large, ground-based observatories. These facilities combine extreme adaptive optics and coronagraphy to achieve unprecedented sensitivities for exoplanet detection and spectral characterization. However, non-common path aberrations (NCPA) in these...

Coronagraphic imaging of exoplanets and circumstellar environments using ground-based instruments on large telescopes is intrinsically limited by speckles induced by uncorrected aberrations. These aberrations originate from the imperfect correction of the atmosphere by an extreme adaptive optics system; from static optical defects; or from...

Context. Since 1995 and the first discovery of an exoplanet orbiting a main-sequence star, 4000 exoplanets have been discovered using several techniques. However, only a few of these exoplanets were detected through direct imaging. Indeed, the imaging of circumstellar environments requires high-contrast imaging facilities and accurate control...

Proxima Centauri, our closest stellar neighbour, is a low-mass M5 dwarf orbiting in a triple system. An Earth-mass planet with an 11 day period has been discovered around this star. The star's mass has been estimated only indirectly using a mass-luminosity relation, meaning that large uncertainties affect our knowledge of its properties. To...

Context. An edge-on debris disk was detected in 2015 around the young, nearby A0V star HD 110058. The disk showed features resembling those seen in the disk of β Pictoris that could indicate the presence of a perturbing planetary-mass companion in the system. Aims. We investigated new and archival scattered light images of the disk in order to...

Context. Debris disks are the natural by-products of the planet formation process. Scattered or polarized light observations are mostly sensitive to small dust grains that are released from the grinding down of bigger planetesimals. Aims. High angular resolution observations at optical wavelengths can provide key constraints on the radial and...

International audience

Context. WR104 is an emblematic dusty Wolf-Rayet star and the prototypical member of a subgroup hosting spirals that are mainly observable with high-angular resolution techniques. Previous aperture masking observations showed that WR104 is likely an interacting binary star at the end of its life. However, several aspects of the system are still...

Context. SPHERE, operating at the VLT since 2014, is currently one of the high-contrast instruments with a higher performance. Its adaptive optics system, known as SAXO, will be upgraded to SAXO+, which features the addition of a second stage of adaptive optics. This stage will use a near-infrared pyramid wavefront sensor to record images of...

International audience

Context: Circumstellar disks and self-luminous giant exoplanets or companion brown dwarfs can be characterized through direct-imaging polarimetry at near-infrared wavelengths. SPHERE/IRDIS at the Very Large Telescope has the capabilities to perform such measurements, but uncalibrated instrumental polarization effects limit the attainable...

International audience

Context. The discovery of planets orbiting at less than 1 au from their host star and less massive than Saturn in various exoplanetary systems revolutionized our theories of planetary formation. The fundamental question is whether these close-in low-mass planets could have formed in the inner disk interior to 1 au, or whether they formed...

The recent discovery of an earth‐like planet around Proxima Centauri has drawn much attention to this star and its environment. We performed a series of observations of Proxima Centauri using Spectro‐Polarimetric High‐contrast Exoplanet REsearch (SPHERE), the planet‐finder instrument installed at the European Southern Observatory (ESO) Very...

Context. R Aqr is a symbiotic binary system consisting of a mira variable, a hot companion with a spectacular jet outflow, and an extended emission line nebula. Because of its proximity to the Sun, this object has been studied in much detail with many types of high resolution imaging and interferometric techniques. We have used R Aqr as test...