SOHO SOI/MDI Results


SOI/MDI on SOHO.

The Solar Oscillations Investigation (SOI) uses the Michelson Doppler Imager (MDI), one of twelve Solar and Heliospheric Observatory (SOHO) instruments. MDI has the highest spatial resolution of the three helioseismology instruments on SOHO. SOI/MDI probes the interior of the Sun by measuring the photospheric manifestations of solar oscillations. Characteristics of the acoustic wave modes reveal the static and dynamic properties of the solar convection zone and interior core. Knowledge of these properties will improve our understanding of the solar cycle and of stellar evolution. Other SOI/MDI photospheric observations will contribute to our knowledge of the solar magnetic field and surface motions.

On Saturday, 2 December 1995, the spacecraft was launched into a halo orbit around the Earth-Sun L1 Lagrange point. The MDI power was turned on the next day, and a week later, the image processor and other electronics were turned on. We received our first image back on 19 December 1995. The results on this page show some of our early images, highlights from recent papers and other results of more in-depth observational campaigns.


Highlights from Recent Papers

Sound Speed Variations.   Horizontal Flow Map.

Solar Rotation Rate   Time-Distance Analysis


Solar Sounds

Sounds Generated From MDI Data.


Technical Reports

SOI/MDI After One Year (NASA/ESA Report, January 1997).

Images from the SOI/MDI (SOI-TN-96-136, June 1996).


Press/Meetings Presentations

Magnetic Carpet (NASA Space Science Update, November 1997).

Plasma Rivers (NASA Space Science Update, August 1997).

Corrugated Sun (AGU, San Francisco, December 1996).

Solar Dynamo Position (AGU, San Francisco, December 1996).

Three-D Power Spectrum (Nice, France, September 1996).

Inversion with Convection Cut (AAS, June 1996).

Sub-Surface Flow Map (ESA SOHO First Reults).

Some Press Releases.


Early Results
MDI "First light". MDI aligned.
First Dopplergrams. First Dopplergram Series.
Early Magnetogram. First High Res Magnetogram.


Related WWW Links


Go to:

  The SOI Main Page.


Last Modified by Amara Graps, SOI, on 5 January 1998.