European Helio- and Asteroseismology Network (HELAS)
Local Helioseismology Network Activity
SDO Outreach Material
NASA's Solar Dynamics Observatory is designed to help us understand the Sun's influence on Earth and Near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously. It is a space based observatory that was launched in February 2010 which observes the Sun 24 hours per day, 7 days per week, 365 days per year.
The focus of the general science is on
i. discovering how the Sun's magnetic field is generated and structured
and
ii.
how this magnetic energy is stored and released into
space.
The released energy is what primarily dictates Space Weather as the solar wind ejects charged particles far into the solar system affecting the atmospheres of all the planets, including the Earth's.
SDO has three instruments onboard:
i. The Helioseismic and Magnetic Imager (HMI) measures the solar oscillations and photospheric magnetic fields with unprecedented resolution;
ii. the Atmospheric Imaging Assembly (AIA) takes high resolution images of the different layers of the Sun's atmosphere;
iii. and the Extreme Ultraviolet Imaging Experiment
(EVE) measures the Sun's ultraviolet brightness.
Each of these instruments contributes to the further understanding of our closest star. The SDO is the successor to SOHO which is still in operation (since 1996), and as such each instrument has higher cadence and spatial resolution making SDO the preeminant solar observatory.
How does SDO help local helioseismology?
The Helioseismic and Magnetic Imager makes measurements of the motion of the solar photosphere for helioseismology as well as measurements of the polarisation of a spectral line to study all three components of the photospheric magnetic field. It is designed to study the origin of solar variability and to characterise and understand the Sun’s interior and the various components of magnetic activity. In particular,
- the solar dynamo: how deep is it located? how thick is it? how does it vary? what happens to the magnetic field in the convection zone?
- sunspots and active regions: how do they form? how do they remain intact? what determines their lifetime and evolution?
- the connection from the interior to the exterior: how does the magnetic activity in, and at the surface of, the Sun influence the activity in the chromosphere and corona?
- predictive power: can we forecast space weather using the solar oscillations as a precursor?
Analysis of the observations made by the HMI will hopefully answer these imposing questions.
