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First Light for VLT's ESPRESSO Exoplanet Hunter

Accepted submission by takyon at 2017-12-06 14:19:11
Science

The Echelle SPectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations [wikipedia.org] (ESPRESSO) has begun operations [sciencemag.org] at the Very Large Telescope [wikipedia.org] in Chile:

A new exoplanet-hunting instrument, attached to one of the world's largest telescopes, has seen its first glimpse of the sky, the European Southern Observatory (ESO) announced today [eso.org]. The Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) detects exoplanets by measuring shifts in the spectrum of light from stars caused by the gravity of planets tugging on them. For this technique, the signal of the stellar wobble is bigger for more massive planets in closer orbits. ESPRESSO, with improved spectral resolution, a wider wavelength range, and fixed to ESO's Very Large Telescope (VLT) at Cerro Paranal in Chile, hopes to discern the fainter tugs of planets with Earth-like masses and orbits.

"It's the most mature facility in the world of this kind," says astronomer Didier Queloz of Cambridge University in the United Kingdom, co-discoverer of the first exoplanet around a normal star in 1995. [...] The previous generation of spectrographs could reach stellar wobbles of around 1 meter per second—a slow walking pace. Jupiter, for example, shifts the sun by 13 meters per second, but Earth's much weaker tug only achieves a velocity of 9 centimeters per second. ESPRESSO, at the forefront of the new generation, aims to put Earth-like planets within reach, with a sensitivity of 10 centimeters per second or even slower. "We're the first to be mad enough to try to achieve that," says lead scientist Francesco Pepe of the University of Geneva in Switzerland.

An exact twin of Earth is probably out of reach, but ESPRESSO should be able to detect super-Earths three or four times heavier than Earth that orbit sun-like stars. It may also detect Earth-sized planets around smaller stars, where a weaker tug achieves more movement.

ESPRESSO is roughly three times more sensitive than HARPS [wikipedia.org]. The CODEX spectrograph attached to the Extremely Large Telescope [wikipedia.org] (ELT) should be about five times more sensitive than ESPRESSO. The ELT's first light is scheduled for 2024.

Also at Space.com [space.com].


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