In Search of New Super Earths: CRIRES+ on ESO’s Very Large Telescope Sees First Light

Since its first light in 2006, the high-resolution infrared CRIRES spectrograph on ESO’s Very Large Telescope (VLT) has made a number of exciting scientific discoveries. The new and improved CRIRES⁺, which has now seen first light, will develop the work of its predecessor and search for potentially habitable super-Earth exoplanets.

CRIRES⁺, an instrument built by ESO in collaboration with a consortium of European institutes, will search the sky for super-Earths located within the habitable zones of nearby low-mass stars, the range of planetary orbits within which scientists believe a planet can support life. These types of planets are difficult to detect due to their relatively low masses. With CRIRES⁺, scientists will be better equipped to search for these super-Earths as they will be able to survey most stars in our stellar neighbourhood. Other science goals of CRIRES⁺ include studying the atmosphere of transiting exoplanets and the origin and evolution of stellar magnetic fields.

The installation of the instrument on ESO’s VLT at ESO’s Paranal Observatory in Chile was completed in late February last year, with first light expected to happen shortly after. However, the COVID-19 pandemic forced the delay of the first test observations, which were scheduled remotely from ESO’s headquarters in Garching in a first for ESO.

CRIRES⁺ builds upon its predecessor, CRIRES. Short for CRyogenic high-resolution InfraRed Echelle Spectrograph, CRIRES was installed on the VLT in 2006. It is a spectrograph, an instrument that splits incoming infrared light into its separate colours, and is assisted by an adaptive optics module, which corrects for image distortions that can arise due to the Earth’s turbulent atmosphere.

Now, nearly fifteen years later, CRIRES has received an important upgrade that has transformed this VLT instrument and refurbished its adaptive optics system. “The upgrade increases the wavelength range that is covered simultaneously by a factor of ten,” according to the ESO project manager for CRIRES⁺, Reinhold Dorn. “CRIRES⁺ is accessing a parameter space up to now largely uncharted at the VLT,” he adds.

Since its installation, CRIRES achieved many scientific discoveries such as measuring the length of a day on an exoplanet for the first time and determining the temperature of Pluto’s entire atmosphere. Scientists hope to use CRIRES⁺ to build upon the remarkable achievements made with CRIRES.

“CRIRES+ will be the only high-resolution infrared spectrograph mounted on an 8-metre class telescope equipped with a state-of-the-art adaptive-optics system. This will make it a game-changer in the study of exoplanets and low-mass stars,” says lead scientist for CRIRES⁺, the Consortium Principal Investigator Artie Hatzes, from the Thuringian State Observatory Tautenburg, Germany. “In particular, CRIRES+ will be unsurpassed in its ability to study exoplanetary atmospheres using ground-based observations.”

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The ESO-led CRIRES⁺ consortium consists of ESO (Germany, Chile), the Institut für Astrophysik, Georg-August Universität Göttingen (Germany), Thüringer Landessternwarte Tautenburg (Germany), Department for Physics and Astronomy, University of Uppsala (Sweden), INAF Osservatorio di Arcetri (Italy), INAF Osservatorio di Bologna (Italy). The instrument’s principal investigator is Artie Hatzes of the Thüringer Landessternwarte Tautenburg (Thuringian State Observatory Tautenburg), Germany. 

Courtesy of European Southern Observatory