Solar Mystery Nears Solution with Data from SOHO Spacecraft
The Sun's Newly-discovered Magnetic Carpet May Explain Coronal Heating

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Scientists may have solved one of the major mysteries of the Sun. Recent observations with the joint European Space Agency/NASA Solar and Heliospheric Observatory (SOHO) spacecraft have shown that the transfer of magnetic energy, via a solar "magnetic carpet", from the Sun's surface to its outlying corona may explain why the Sun's coronal temperature is 300 times hotter than its gaseous surface.

The new observations are the latest made by the Solar Oscillations Investigation (SOI) group at Lockheed-Martin Solar and Astrophysics Laboratory and Stanford University, They build on discoveries by the SOI and SOHO science teams over the past year.

Press Release Full Text


Movies

For information about obtaining the movies, contact Neal Hurlburt, 650-354-5504.

Click on each image to view the movie.

[GIF snapshot]
(21 Mbyte, QuickTime)
Theoretical predictions for the structure and heating of the magnetic field above the solar surface using data for the magnetic data from MDI are compared to the heating observed by EIT. The white magnetic fieldlines eminate from the magnetic carpet and form arches from one magnetic polarity (white) to the other (black). Current theories predict that length and curvature of these arches determine the degree to which they are heated. The image underlying the arches is the heating observed at the same time by EIT in the Iron line at 195 Angstroms, with bright green corresponding to relatively hot regions and dark green corresponding to cool ones.

[GIF snapshot]
(8 Mbytes, QuickTime)
The complex distribution and mixing of magnetic polarities (here displayed as black and white) form a "magnetic carpet" over the entire Sun. The magnetic loops, connecting regions of opposing magnetic polarity, rise far into the solar corona, forming extensive loop structures. While the bright active regions have long been known to be sources of heating, the diffuse heating appears to be associated with the ubiquitous magnetic carpet. The relationship between the structure of the magnetic carpet and the heating of the solar corona was discovered by comparing images of the Sun taken simultaneously by the MDI and CDS instruments on SOHO.

[GIF snapshot]
(14 Mbyte, QuickTime)
Magnetic Carpet Walkthrough (EFR)

[GIF snapshot]
(5 Mbyte, QuickTime)
Smaller Feature Magnetic Carpet

[GIF snapshot]
(21 Mbytes, QuickTime)
Reconnection simulation

[GIF snapshot]
(2 Mbytes, QuickTime)
Lower corona

Still Images

Extracted from the movies

For information about the images, contact Neal Hurlburt, 650-354-5504.

Click on each image for a larger verson.

(1 Mbyte JPEG)
Magnetic Carpet Image
This image is a model of magnetic fields at the surface of the Sun developed using data from several instruments on board the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. The data were taken on Oct. 19, 1996. The green and white plane in the foreground is from the solar corona from the Extreme Ultraviolet Imaging Telescope (EIT) instrument.

The solar corona is a region of hot, electrically charged gas streaming from the surface of the Sun. The image shows different amounts of coronal material at a temperature of about 2.7 million degrees Fahrenheit. Whiter areas represent more material at this temperature, darker areas represent less. The black and white spots represent magnetic field concentrations with opposite orientations, called polarity. Each spot is roughly 5,000 miles across. These concentrations make up the solar "magnetic carpet" that is believed to be responsible for the extreme heating of the corona.

Between pairs of opposite polarity, magnetic field connections exist, represented here by lines based on computer calculations. These horseshoe shaped loops extend above the surface into the corona. Although small relative to the Sun, they range between a few thousand to several tens of thousands of miles in length; the smallest would still fit around the Earth. Each one of these loops carries as much energy as a large hydroelectric plant, such as the Hoover dam, would generate over a million years.

(Photo Credit: Stanford-Lockheed Institute for Space Research, Palo Alto, CA and NASA Goddard Space Flight Center, Greenbelt, MD)



(120K JPEG)
Magnetic Carpet Movie Still -- View 1


(110K JPEG)
Magnetic Carpet Movie Still -- View 2


(1 Mbyte JPEG)
Magnetic Carpet Movie Still -- View 3


Related Images

Click on each image for a larger verson.

[1991 eclipse thumbnail]
(200K JPEG)
Solar Corona Image
Correction: This image was previously creditted to High Altitude Observatory/ National Center for Atmospheric Research, Boulder, CO but it has been brought to our attention (22 Aug 2001) that it was made by Steve Albers. A better version of the image can be found at Steve Albers home page. The image is a composit of images taken from Baja California, Mexico rather than from Mauna Kea Hawaii as previously stated. The black disk is the moon, and the pink, feathery extensions are the solar corona. The corona is a region of hot, electrically charged gas streaming from the surface of the Sun. The average temperature of this gas is approximately 3.6 million degrees Fahrenheit, and its furthest extension here is about 1 million miles from the surface. The extreme temperature of the corona has been a long standing astronomical mystery, since the solar surface is a relatively cool 11,000 degrees Fahrenheit. If the corona was at this much lower temperature, it would be held very close to the solar surface and, hence, would not be visible at all from the Earth.


[1980 eclipse thumbnail]
(360K JPEG)
1980 total eclipse
(Credit: High Altitude Observatory/ National Center for Atmospheric Research)

[1988 eclipse thumbnail]
(640K JPEG)
1988 total eclipse
(Credit: High Altitude Observatory/ National Center for Atmospheric Research)

[1994 eclipse thumbnail]
(200K JPEG)
1994 total eclipse
(Credit: High Altitude Observatory/ National Center for Atmospheric Research)


GIF Format     TIFF Format
EIT Fe XII 195 Å image showing ephemeral regions as well as post-flare loops


Background and Related Information

Stanford SOLAR Center


Authors and Contacts

Press Release No: N97-147 (HQ 97-256), 5 November 1997

Donald Savage
NASA Headquarters
Washington, DC
(Phone: 202/358-1547)

Bill Steigerwald
Goddard Space Flight Center
Greenbelt, MD
(Phone: 301-286-0697)

Alan M. Title
Solar and Astrophysics Department
Lockheed Martin Missiles & Space Company, Inc.
650-424-4034 FAX 650-424-3994

SOI Home Page
SOHO Home Page


Some Reports in the Media

ABC News Online

NBC News Online

Astronomy Picture of the Day

San Jose Mercury News (November 11, 1997)




Research has been supported financially at Stanford University by the National Aeronautics and Space Administration (NASA) through Grant NAG5-3077. This grant supports Mission Operations and Data Analysis of the Solar Oscillations Investigation Michelson Doppler Imager instrument on the SOlar and Heliospheric Observatory (SOHO). The SOlar and Heliospheric Observatory (SOHO) is a mission of international cooperation between ESA (the European Space Agency) and NASA.

The MDI instrument was designed and built by the Lockheed-Martin Solar and Astrophysics Laboratory and the Solar Oscillations Investigation Team at Stanford University.


Created by Joseph B. Gurman, Neal Hurlburt, and Deborah Scherrer
This page is http://soi.stanford.edu/press/ssu11-97/
Last Updated by DKS 12 November 1997

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