Proposed visible emission line space solar coronagraph

Abstract

The outer atmosphere of the sun – called the corona – has been observed during total solar eclipse
\nfor short periods (typically < 6 min), from as early as the eighteenth century. In the recent past,
\nspace-based instruments have permitted us to study the corona uninterruptedly. In spite of these
\ndevelopments, the dynamic corona and its high temperature (1–2 million K) are yet to be fully
\nunderstood. It is conjectured that their dynamic nature and associated energetic events are possible
\nreasons behind the high temperature. In order to study these in detail, a visible emission line space
\nsolar coronagraph is being proposed as a payload under the small-satellite programme of the
\nIndian Space Research Organisation. The satellite is named as Aditya-1 and the scientific objectives
\nof this payload are to study: (i) the existence of intensity oscillations for the study of wavedriven
\ncoronal heating; (ii) the dynamics and formation of coronal loops and temperature structure
\nof the coronal features; (iii) the origin, cause and acceleration of coronal mass ejections (CMEs)
\nand other solar active features, and (iv) coronal magnetic field topology and three-dimensional
\nstructures of CMEs using polarization information. The uniqueness of this payload compared to
\npreviously flown space instruments is as follows: (a) observations in the visible wavelength closer
\nto the disk (down to 1.05 solar radii); (b) high time cadence capability (better than two-images per
\nsecond), and (c) simultaneous observations of at least two spectral windows all the time and three
\nspectral windows for short durations.