The main science questions which EST will address are:
- How does the magnetic field emerge to the surface and evolve?
- How is the energy transported from the photosphere to the chromosphere?
- How is the energy released and deposited in the upper atmosphere?
- Why does the Sun have a hot chromosphere?
The top-level science goals, as structured and described in the SRD, are :
I. Structure and evolution of magnetic flux
- Formation and disappearance of kG flux concentrations in the solar photosphere
- Magnetopauses and current sheets in the solar atmosphere
- Small-scale flux emergence in the quiet Sun
- Magnetic flux cancellations in the quiet Sun
- Quiet Sun internetwork fields
- Polar magnetic fields
II. Photospheric/chromospheric magnetic coupling
- Magnetic topology of the photosphere and chromosphere
- Conversion of mechancial to magnetic energy in the photosphere
- Magnetic twist and torsion
III. Chromospheric structure, dynamics and heating
- Wave propagation from photosphere to chromosphere
- Energy dissipation in the chromosphere
- Large-scale chromospheric release of magnetic energy
- Observational determination of electric currents
- Hanle diagnostics of chromospheric fields
- The COmosphere
IV. Magnetized plasma processes
- Dynamics of large-scale magnetic structures
V. The solar corona
VI. The explosive Sun
- Solar flares and space weather
VII. Atomic physics
- Spectro-polarimetric observations involving atomic physics phenomena
VIII. Non-solar astrophysics
The EST science will focus mainly on those aspects related to solar polarimetry on the disk at very high spatial resolution, particularly for the diagnostics of magnetic fields and dynamics of the photosphere and chromosphere. The Science Team has been encouraged, though, to pursue the possibility of observing the solar corona with EST if this can be accomplished at no (or relatively low) additional cost. Also, it has been asked to consider other non-solar scientific problems that EST may address without adding further burden to the project. Based on these considerations, objective V is considered of second priority, and objective VIII of third priority.