CRIRES+: enabling high-resolution near-infrared spectroscopy and spectropolarimetry at the 8-m Very Large Telescope

CRIRES+ is the fully refurbished and greatly enhanced near-infrared CRyogenic high-resolution Infrared Echelle Spectrograph (CRIRES) that will be offered to the entire astronomical community in 2021. CRIRES+ combines high spectral resolution and full near-infrared coverage, and enables a variety of long awaited scientific opportunities. CRIRES+ is an adaptive optics fed high-resolution (R~100000) near-infrared spectropolarimeter installed at one of the 8-m unit telescopes of the European Southern Observatory Very Large Telescope in Paranal, Chile. CRIRES+ operates in spectroscopy mode from 0.95 to 5.2 μm (YJHKLM bands) and in spectropolarimetry mode between 0.95 and 2.5 μm (YJHK). The instrument boasts an overall increase in efficiency compared to the original CRIRES, a tenfold increase in simultaneous wavelength coverage thanks to a new cross-dispersed design (now ~150 nm), and improved stability and repeatability. Additionally, a new powerful data reduction pipeline as well as new wavelength calibration capabilities including new gas cells and a Fabry-Perot etalon will allow to reach a few m/s in RV precision. The unique combination of the 8-m VLT collecting power, the R=100000 spectral resolution, and spectroscopic coverage up to 5.2 μm makes CRIRES+ a game-changing instrument for the study of exoplanetary atmospheres, stellar magnetism, low-mass objects, and other science cases.