%0 Journal Article
%T MIRACLES: atmospheric characterization of directly imaged planets and substellar companions at 4每5 米m - I. Photometric analysis of 汕 Pic b, HIP 65426 b, PZ Tel B, and HD 206893 B
%A B. Lavie
%A J. K邦hn
%A K. O. Todorov
%A M. R. Meyer
%A P. Molli豕re
%A S. Daemgen
%A S. P. Quanz
%A T. Currie
%A T. Stolker
%J -
%D 2020
%R 10.1051/0004-6361/201937159
%X <i>Context.<i/> Directly imaged planets and substellar companions are key targets for the characterization of self-luminous atmospheres. Their photometric appearance at 4每5 <i>米<i/>m is sensitive to the chemical composition and cloud content of their atmosphere.<i>Aims.<i/> We aim to systematically characterize the atmospheres of directly imaged low-mass companions at 4每5 <i>米<i/>m. We want to homogeneously process the data, provide robust flux measurements, and compile a photometric library at thermal wavelengths of these mostly young, low-gravity objects. In this way, we want to find trends related to their spectral type and surface gravity by comparing with isolated brown dwarfs and predictions from atmospheric models.<i>Methods.<i/> We used the high-resolution, high-contrast capabilities of NACO at the Very Large Telescope (VLT) to directly image the companions of HIP 65426, PZ Tel, and HD 206893 in the NB4.05 and/or <i>M<i/>∩ filters. For the same targets, and additionally <i>汕<i/> Pic, we also analyzed six archival VLT/NACO datasets which were taken with the NB3.74, <i>L<i/>∩, NB4.05, and <i>M<i/>∩ filters. The data processing and photometric extraction of the companions was done with PynPoint while the species toolkit was used to further analyze and interpret the fluxes and colors.<i>Results.<i/> We detect for the first time HIP 65426 b, PZ Tel B, and HD 206893 B in the NB4.05 filter, PZ Tel B and HD 206893 B in the <i>M<i/>∩ filter, and <i>汕<i/> Pic b in the NB3.74 filter. We provide calibrated magnitudes and fluxes with a careful analysis of the error budget, both for the new and archival datasets. The <i>L<i/>∩每NB4.05 and <i>L<i/>∩每<i>M<i/>∩ colors of the studied sample are all red while the NB4.05每<i>M<i/>∩ color is blue for <i>汕<i/> Pic b, gray for PZ Tel B, and red for HIP 65426 b and HD 206893 B (although typically with low significance). The absolute NB4.05 and <i>M<i/>∩ fluxes of our sample are all larger than those of field dwarfs with similar spectral types. Finally, the surface gravity of <i>汕<i/> Pic b has been constrained to dex from its photometry and dynamical mass.<i>Conclusions.<i/> A red color at 3每4 <i>米<i/>m and a blue color at 4每5 <i>米<i/>m might be (partially) caused by H<sub>2<sub/>O and CO absorption, respectively, which are expected to be the most dominant gaseous opacities in hot (<i>T<i/><sub>eff<sub/> ˋ 1300 K) atmospheres. The red characteristics of <i>汕<i/> Pic b, HIP 65426 b, and HD 206893 B at 3每5<i>米<i/>m, as well as their higher fluxes in NB4.05 and <i>M<i/>∩ compared to field dwarfs, indicate that cloud
%U https://www.aanda.org/articles/aa/full_html/2020/03/aa37159-19/aa37159-19.html