MDI shows view beneath Active Region and Rotating Spot

Analysis of MDI data has revealed interesting features beneath the largest active region of this cycle (so far) and beneath a rare rapidly rotating spot.

With the assistance of Stanford and NASA press offices the following statement was released on Dec 10, 2001 at the Fall AGU meeting in San Francisco.

See also:
SOHO HotShot page for 10 Dec 2001.

This is the first time we have seen such detail to such depth in a developing active region. We see that the thermal signature of the active region goes down to at least 100 Mm and that it shows variation changing with time and not just under the surface manifestations of the region.

In the second paper, Junwei Zhao, Tom Duvall, and Alexander Kosovichev saw shearing flows in the form of reversing vortices beneath a spot pair (one large and one small) that were spinning about each other.

In each of these results we have seen details not seen before. As Douglas Gough once said, "The Sun's interior has been seen as simple only because we have not had data". Now that we have observations of the thermal structure and flows beneath interesting regions we find complexity not simplicity.

The following images and movies show these results.

TopicSample ImageImage or Video links Notes
AR9393 March 2001  Mpeg(1.2Meg) Tracked MDI Continuum Proxy
Interior of 9393  Mpeg(1.0Meg) Sound speed beneath 9393
Life of AR9393 Whole Sun - front and farside Mpeg(3.2meg)
Farside and Frontside for life of AR9393. March to June 2001
MDI Continuum for 9393 passage MDI image 29 March 01 Full field MDI movies: QuickTime, MPEG (large , small).
Subfield movies: MDI QuickTime MPEG (large, small), GIF animation.
MDI Full disk and extracted latitude movies
Rotating Sunspot Rotating Spot
Rotating Spot
Rotating Spot
Rotating Spot
Frame 1 Still
Frame 92 Still
Frame 302 Still
Frame 530 Still
Spinning spot animation prepared by NASA
Sound Speed and Flow Layers Beneath Sunspot Surface
Beneath Spot
Deeper Beneath Spot
Frame 123 Still
Frame 183 Still
Frame 243 Still
Sound speed and flow beneath spot. MDI time-distance analysis
Emerging Spot Aimation

MPEG (3.7meg)
Quicktime (12meg)
Animation showing the conceptual picture of an emerging spot region. First a magnetic loop rises from beneath the surface (photosphere) then rises through the surface creating sunspots. Later more flux emerges and reconnects with the initial loops to cause a flare and CME.

Further information about the large region 9393 can be found at the SOHO "Hot Shot" page for 29 March 2001.

The NOAA Space Environment Center (SEC) tracks all solar active regions and give them numbers (e.g. AR9393). Region 9393 was seen on the disk over more than 3 months with the region visible for four disk passages. It had a different number for each passage. The daily location and size of the region while seen on the front side of the Sun is in the SRS Region data for region 9393 under the names 9371, 9393, 9433, and 9461 for the four disk passages of this region in Carrington Rotations 1973, 1974, 1975, and 1976 respecively. The SRS data prepared by NOAA Space Environment Lab described in a Readme file. The NOAA SEC site contains many useful links and datasets for space weather information.

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