RISTRETTO: high-resolution spectroscopy at the diffraction limit of the VLT

• Main Authors: Lovis, Christophe, Blind, Nicolas, Chazelas, Bruno, Kühn, Jonas G, Genolet, Ludovic, Hughes, Ian, Sordet, Michaël, Schnell, Robin, Turbet, Martin, Fusco, Thierry, Sauvage, Jean-François, Bugatti, Maddalena, Billot, Nicolas, Hagelberg, Janis, Hocini, Eddy, Guyon, Olivier, Mordasini, Christoph
• Format: Journal Article
• Language: English
• Published: 31-08-2022
• Subjects: Physics - Earth and Planetary Astrophysics; Physics - Instrumentation and Methods for Astrophysics
• DOI: 10.48550/arxiv.2208.14838

Proc. SPIE 12184, Ground-based and Airborne Instrumentation for
Astronomy IX, 121841Q (29 August 2022) RISTRETTO is a visible high-resolution spectrograph fed by an extreme
adaptive optics (XAO) system, to be proposed as a visitor instrument on ESO
VLT. The main science goal of RISTRETTO is the detection and atmospheric
characterization of exoplanets in reflected light, in particular the temperate
rocky planet Proxima b. RISTRETTO will be able to measure albedos and detect
atmospheric features in a number of exoplanets orbiting nearby stars for the
first time. It will do so by combining a high-contrast AO system working at the
diffraction limit of the telescope to a high-resolution spectrograph, via a
7-spaxel integral-field unit (IFU) feeding single-mode fibers. Further science
cases for RISTRETTO include the study of accreting protoplanets such as PDS 70
b & c through spectrally-resolved H-alpha emission; and spatially-resolved
studies of Solar System objects such as icy moons and the ice giants Uranus and
Neptune. The project is in an advanced design phase for the spectrograph and
IFU/fiber-link sub-systems, and a preliminary design phase for the AO
front-end. Construction of the spectrograph and IFU/fiber-link will start at
the end of 2022. RISTRETTO is a pathfinder instrument in view of similar
developments at ESO ELT, in particular the SCAO-IFU mode of ELT-ANDES and the
future ELT-PCS instrument.