First light of VLT/HiRISE: High-resolution spectroscopy of young giant exoplanets

¹ Aix-Marseille Univ., CNRS, CNES, LAM, Marseille, France
e-mail: arthur.vigan@lam.fr
² Institute for Astrophysics, Georg-August University, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
³ European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
⁴ Center for Advanced Instrumentation, Durham University, Durham DH1 3LE, UK
⁵ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
⁶ Physics & Astronomy Department, University of Exeter, Exeter EX4 4QL, UK
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
⁸ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁹ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹⁰ Academia Sinica, Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, NTU/AS campus, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan
¹¹ Dept. of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
¹² Optical and Electronic Systems Department, Kazan National Research Technical University Named after A.N. Tupolev KAI, 10 K. Marx, 420111 Kazan, Russia
¹³ Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USA
¹⁴ École Normale Supérieure de Lyon, CRAL (UMR CNRS 5574), Université de Lyon, Lyon, France
¹⁵ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

Received: 19 September 2023
Accepted: 23 October 2023

Abstract

A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of their atmosphere and infer their formation processes and evolution. Such a goal represents a major challenge owing to their small angular separation and luminosity contrast with respect to their parent stars. Instead of designing and implementing completely new facilities, it has been proposed to leverage the capabilities of existing instruments that offer either high-contrast imaging or high-dispersion spectroscopy by coupling them using optical fibers. In this work, we present the implementation and first on-sky results of the High-Resolution Imaging and Spectroscopy of Exoplanets (HiRISE) instrument at the Very Large Telescope (VLT), which combines the exoplanet imager SPHERE with the recently upgraded high-resolution spectrograph CRIRES using single-mode fibers. The goal of HiRISE is to enable the characterization of known companions in the H band at a spectral resolution on the order of R = λ/∆λ = 100 000 in a few hours of observing time. We present the main design choices and the technical implementation of the system, which is constituted of three major parts: the fiber injection module inside of SPHERE, the fiber bundle around the telescope, and the fiber extraction module at the entrance of CRIRES. We also detail the specific calibrations required for HiRISE and the operations of the instrument for science observations. Finally, we detail the performance of the system in terms of astrometry, temporal stability, optical aberrations, and transmission, for which we report a peak value of ~3.9% based on sky measurements in median observing conditions. Finally, we report on the first astrophysical detection of HiRISE to illustrate its potential.