The IACAT (IAC Atmosphere and Telescope) Simulator is an Optical Ground Support Equipment which simulates atmospheric turbulence and reproduces the performance of three very different telescopes: GTC and WHT, located at the Observatorio Del Roque de los Muchachos in La Palma (Canary Islands), and OGS which is located at the Observatorio Del Teide

Context. The physical conditions of the solar photosphere change on very small spatial scales both horizontally and vertically. Such a complexity may pose a serious obstacle to the accurate determination of solar magnetic fields. Aims: We examine the applicability of Milne-Eddington (ME) inversions to high spatial resolution observations of the

In the last six years, thanks to the very high radial velocity precision of the HARPS spectrograph, it was possible to detect 21 out of the 30 super-Earth (extrasolar planets masses below 20 times the mass of the Earth) discovered up to date. The radial velocity precision of the instrument is estimated around 80 cm/s on a single measurement. The

A consortium of more than 20 European solar physics institution from 15 different countries is conducting a design study for a 4 m class solar telescope which shall be situated at the Canary Islands. In this paper we introduce the AO and MCAO design concept for EST. A ground layer deformable mirror is combined with an arrangement of four deformable

Context. Starbursts are one of the main contributors to the chemical enrichment of the interstellar medium. However, mechanisms governing the interaction between the recent star formation and the surrounding gas are not fully understood. Because of their a priori simplicity, the subgroup of H II galaxies constitute an ideal sample to study these

The Sun is a variable star whose magnetic activity varies most perceptibly on a timescale of approximately 11 years. However, significant variation is also observed on much shorter timescales. We observe a quasi-biennial (2 year) signal in the natural oscillation frequencies of the Sun. The oscillation frequencies are sensitive probes of the solar