HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. The high-contrast module (HCM) has been designed to characterize planets as close as 100mas from their host star (goal: 50mas), and presenting a 1e-6 flux ratio with it. To do so, it will use (1) a passive atmospheric dispersion corrector, (2) a set of amplitude apodizers and focal plane masks to lower the diffracted intensity next to the star and attenuate the PSF core, (3) a dedicated Zernike wavefront sensor to track the non-common path aberrations with the SCAO subsystem at a 0.1Hz frequency, and (4) post-processing algorithms that will rely on the temporal and spectral diversity of the IFS data to separate the planetary signals from the noise. This communication details several trade-off analyses involved in the co-design of the hardware of the HCM. It also presents contrast performance estimates that have been derived through an analysis of post-processed, simulated IFS data obtained with an end-to-end numerical model of the HCM and the rest of HARMONI. The respective interests of ADI and molecular mapping are compared in this specific case.
New generation exoplanet imagers on large ground-based telescopes are highly optimised for the detection of young giant exoplanets in the near-infrared, but they are intrinsically limited for their characterisation by the low spectral resolution of their integral field spectrographs (R < 100). High-dispersion spectroscopy at R ≫ 104 would be a powerful tool for the characterisation of these planets, but there is currently no high-resolution spectrograph with extreme adaptive optics and coronagraphy that would enable such characterisation. With project HiRISE we propose to use fiber coupling to combine the capabilities of two flagship instruments at the Very Large Telescope in Chile: the exoplanet imager SPHERE and the high-resolution spectrograph CRIRES+. The coupling will be implemented at the telescope in early 2023. We provide a general overview of the implementation of HiRISE, of its assembly, integration and testing (AIT) phase in Europe, and a brief assessment of its expected performance based on the final hardware.
Combining adaptive optics and interferometric observations results in a considerable contrast gain compared to single-telescope, extreme AO systems. Taking advantage of this, the ExoGRAVITY project is a survey of known young giant exoplanets located in the range of 0.1” to 2” from their stars. The observations provide astrometric data of unprecedented accuracy, being crucial for refining the orbital parameters of planets and illuminating their dynamical histories. Furthermore, GRAVITY will measure non-Keplerian perturbations due to planet-planet interactions in multi-planet systems and measure dynamical masses. Over time, repetitive observations of the exoplanets at medium resolution (R = 500) will provide a catalogue of K-band spectra of unprecedented quality, for a number of exoplanets. The K-band has the unique properties that it contains many molecular signatures (CO, H2O, CH4, CO2). This allows constraining precisely surface gravity, metallicity, and temperature, if used in conjunction with self-consistent models like Exo-REM. Further, we will use the parameter-retrieval algorithm petitRADTRANS to constrain the C/O ratio of the planets. Ultimately, we plan to produce the first C/O survey of exoplanets, kick-starting the difficult process of linking planetary formation with measured atomic abundances.
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