Science with ESPRESSO
The three science drivers of ESPRESSO as defined by ESO are:
- Search for rocky planets: The high-precision radial velocity achievable with ESPRESSO (<10 cm/s in the HR and UHR modes) will allow the detection and characterization of Earth-mass planets in the habitable zone of GKM stars (the Earth imposes a velocity amplitude of 9 cm/s onto the Sun). ESPRESSO will thus fill the gap of rocky planets with measured masses in the temperate region of solar-like stars. Coupled with the large collecting area of the VLT, ESPRESSO will be capable of determining the masses of planets around faint stars (e.g. most Kepler validated planets) and follow-up the new candidates coming from the new space missions like Gaia, TESS or PLATO. Also, ESPRESSO will play an important role in the characterization of exoplanet atmospheres.
- Variation of physical constants: The standard model of particle physics depends on many (≈ 27) independent numerical parameters that determine the strengths of the different forces and the relative masses of all known fundamental particles. Two of these parameters are the fine structure constant (α) and the proton-to-electron mass ratio (µ). Their constancy has been demonstrated in timescales of few years. Astronomy, however, has the opportunity to test this constancy in Gyr timescales by observing the spectra of distant quasars. Only a high-resolution spectrograph that combines a large collecting area with extreme wavelength precision can perform these tests. A relative variation in α or μ of 1 ppm leads to velocity shifts of about 20 m/s between typical combinations of transitions. ESPRESSO is expected to provide an increase in the accuracy of the measurement of these two constants by at least one order of magnitude compared to VLT/UVES.
- Chemical composition of stars in nearby galaxies: To understand galaxy formation, we need to know the chemical composition of local galaxies. ESPRESSO will give us the chance to have a first but important glimpse into this, although extremely large telescopes will be needed to have a definitive answer.
Apart from these three main scientific drivers, ESPRESSO will be an outstanding tool to explore many areas of astronomical research such as: asteroseismology, the study of metal-poor stars, the expansion of the Universe, galactic winds, etc. A summary of these can be found in Pepe et al. (2014).
Science Verification papers
The Science Verification phase of ESPRESSO (in 4-UT mode only) is currently foreseen to take place in January/February 2019 and the corresponding call for proposals will be advertised in due time. In this section, we will summarize the outcomes of this phase.
Selected Science Results
ESPRESSO can be used for a variety of science. A handful of published science cases will be outlined here.