3 research outputs found
The beta Pictoris system: Setting constraints on the planet and the disk structures at mid-IR wavelengths with NEAR
[abridged] We analyzed mid-infrared high-contrast coronagraphic images of the
beta Pictoris system, taking advantage of the NEAR experiment using the
VLT/VISIR instrument. The goal of our analysis is to investigate both the
detection of the planet beta Pictoris b and of the disk features at mid-IR
wavelengths. In addition, by combining several epochs of observation, we expect
to constrain the position of the known clumps and improve our knowledge on the
dynamics of the disk. To evaluate the planet b flux contribution, we extracted
the photometry and compared it to the flux published in the literature. In
addition, we used previous data from T-ReCS and VISIR, to study the evolution
of the position of the southwest clump that was initially observed in the
planetary disk back in 2003. While we did not detect the planet b, we were able
to put constraints on the presence of circumplanetary material, ruling out the
equivalent of a Saturn-like planetary ring around the planet. The disk presents
several noticeable structures, including the known southwest clump. Using a
16-year baseline, sampled with five epochs of observations, we were able to
examine the evolution of the clump: the clump orbits in a Keplerian motion with
an sma of 56.1+-0.4 au. In addition to the known clump, the images clearly show
the presence of a second clump on the northeast side of the disk and fainter
and closer structures that are yet to be confirmed. We found correlations
between the CO clumps detected with ALMA and the mid-IR images. If the
circumplanetary material were located at the Roche radius, the maximum amount
of dust determined from the flux upper limit around beta Pictoris b would
correspond to the mass of an asteroid of 5 km in diameter. Finally, the
Keplerian motion of the southwestern clump is possibly indicative of a
yet-to-be-detected planet or signals the presence of a vortex.Comment: Accepted in Astronomy and Astrophysic
Lessons learned from the NEAR experiment and prospects for the upcoming mid-IR HCI instruments
editorial reviewedThe mid-infrared (IR) regime is well suited to directly detect the thermal signatures of exoplanets in our solar neighborhood. The NEAR experiment: demonstration of high-contrast imaging (HCI) capability at ten microns, can reach sub-mJy detection sensitivity in a few hours of observation time, which is sufficient to detect a few Jupiter mass planets in nearby systems. One of the big limitations for HCI in the mid-IR is thermal sky-background. In this work, we show that precipitate water vapor (PWV) is the principal contributor to thermal sky background and science PSF quality. In the presence of high PWV, the HCI performance is significantly degraded in the background limited regime
Imaging low-mass planets within the habitable zone of α Centauri
Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged. Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, alpha Centauri. Based on 75-80% of the best quality images from 100h of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of alpha Centauri A. This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around alpha Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes. Imaging of low-mass exoplanets can be achieved once the thermal background in the mid-infrared (MIR) wavelengths can be mitigated. Here, the authors present a ground-based MIR observing approach enabling imaging low-mass temperate exoplanets around nearby stars