Speaker
Description
EST is the future major infrastructure for ground-based solar physics in Europe. EST will be built in the island of La Palma (Canary Islands, Spain) and is expected to start operations in the next decade. The project is devised to study the solar magnetism of the deepest layers of the solar atmosphere with high spatial, temporal, spectral and polarimetric accuracies, to record how magnetic energy is stored by plasma flows, propagated at large distances and finally released to heat and accelerate the plasma towards the interplanetary space. Understanding these processes is essential to evaluate how the Sun modulates the conditions prevailing in the interplanetary medium and the Earth’s environment, needed for space weather forecast.
To achieve its scientific goals, EST has a number of characteristics that, all together, will make it unique in the world. To obtain the best images ever recorded from the Sun, EST will incorporate a primary mirror, M1, with a diameter of 4.2 m. Only the American DKIST, installed in Hawai’i, has a similar size among solar telescopes. The fabrication of M1 represents a fantastic challenge. It will be the mirror with the largest aspect ratio (diameter/thickness ratio, with a value of s60 for the EST M1) ever constructed. With this M1 size, EST will ensure a large collecting power to reduce the intrinsic shot noise of photon measurements together with a spatial resolution of few tens of km on the Sun. To overcome the limitations imposed by the unavoidable turbulence of the Earth’s atmosphere existing even at the best observatories, EST will be equipped with the most complete and ambitious set of deformable mirrors to compensate for the wavefront deformation induced by the variations of refractive index as light propagates in the Earth’s atmosphere. This compensation will be computed and applied in real time at kHz frequencies.
There will be two observing stations (visible and near-infrared), with room for seven novel powerful instruments whose joint simultaneous use is planned. To maximize efficiency, these instruments will be tuned and optimised for different passbands. Each of these instruments will have polarimetric capabilities. Measuring the polarization of light opens the door to the inference of the solar vector magnetic field. The optical design of EST ensures that the polarimetric performance of the optics in the full optical path from M1 to the instruments is fixed in time, independent of the pointing of the telescope, so that time-consuming calibration and modelling tasks necessary at other telescopes are not required for EST.
The different wavelength regimes of the various instruments make it possible to probe different layers in height in the solar atmosphere. With all this information put together, EST will provide the community with 3D maps of physical quantities (temperature, pressure, density, velocity, magnetic field vector, ionization degree, etc.) and their temporal evolution.
