IRIS

Understanding the interface between the photosphere and corona remains a fundamental challenge in solar and heliospheric science. The Interface Region Imaging Spectrograph (IRIS) mission opens a window of discovery into this crucial region by tracing the flow of energy and plasma through the chromosphere and transition region into the corona using spectrometry and imaging. IRIS is designed to provide significant new information to increase our understanding of energy transport into the corona and solar wind and provide an archetype for all stellar atmospheres. The unique instrument capabilities, coupled with state of the art 3-D modeling, will fill a large gap in our knowledge of this dynamic region of the solar atmosphere. The mission will extend the scientific output of existing heliophysics spacecraft that follow the effects of energy release processes from the sun to Earth.

IRIS will provide key insights into all these processes, and thereby advance our understanding of the solar drivers of space weather from the corona to the far heliosphere, by combining high-resolution imaging and spectroscopy for the entire chromosphere and adjacent regions. IRIS will resolve in space, time, and wavelength the dynamic geometry from the chromosphere to the low-temperature corona to shed much-needed light on the physics of this magnetic interface region.

Science Objectives

The IRIS instrument is a multi-channel imaging spectrograph with a 20 cm UV telescope. IRIS will obtain spectra along a slit (1/3 arcsec wide), and slit-jaw images

The IRIS science investigation is centered on three themes of broad significance to solar and plasma physics, space weather, and astrophysics, aiming to understand how internal convective flows power atmospheric activity:

1.Which types of non-thermal energy dominate in the chromosphere and beyond?

2.How does the chromosphere regulate mass and energy supply to corona and heliosphere?

3.How do magnetic flux and matter rise through the lower atmosphere, and what role does flux emergence play in flares and mass ejections?

The complex processes and enormous contrasts of density, temperature and magnetic field within this interface region require instrument and modeling capabilities that are only now within reach. The IRIS team will use advances in instrumental and computational technology, its extensive experience, and its broad technological heritage to build a state-of-the-art instrument to provide unprecedented access to the plasma-physical processes in the interface region.