Scientists Image the Three-dimensional Surface of the Sun

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1a. Granulation, sunspots, and faculae seen near the limb
The color of the image has been added in processing
Full Image: 3682 x 2185 Pixels, 4.2MB
Image of a solar active region taken on 24-July-2002 near the eastern limb of the Sun at heliographic coordinates S15 E53 degrees. The limb is towards the top of the image. The tick marks are 1000 km apart. The smallest resolvable features in the image are about 70 km in size. The image is a filtergram taken in 488 nm light at the Swedish 1-meter Solar Telescope on the island of La Palma, Spain. The image highlights the three-dimensional nature of the photosphere when seen at these large angles. The structures in the dark sunspots in the upper central area of the image show distinct elevation above the dark "floor" of the sunspot. The height of the structures has been estimated by Dr. Bruce Lites of the High Altitude Observatory to be between 200 and 450 km. There are also numerous bright "faculae" visible on the edges of granules that face towards the observer. The image was taken by Prof. Goran Scharmer and processed by Dr. Mats G. Löfdahl, both of the Institute for Solar Physics of the Royal Swedish Academy of Sciences. It is included in a paper submitted for peer review to the journal 'Solar Physics'.

1b. View of the solar limb and active regions
The color of the image has been added in processing
Full Image: 3333 x 2167 Pixels, 2.9MB
The active region shown in the image above is seen here in a white light image from the TRACE satellite. Tickmarks are 10,000 km apart. TRACE has a much larger field-of-view than the SST and so the solar limb is captured in the same image. The white box outlines the approximate SST field-of-view in the image shown above. TRACE has 10 times less spatial resolution than the SST and so faculae show up here as only vague bright patches surrounding the active regions. Only when looking at active regions towards the solar limb with 70 km spatial resolution of the SST do the three-dimensional aspects of the photosphere and faculae become apparent.

1c. Measurement of sunspot feature height
Closeup of the image shown in 1a with measurements of the height of some of the granular features shown as overlays. Tick marks are 1 arcsecond apart; one arcsecond is about 725 km on the Sun at disk center. The base of the triangles aligns with the dark "floor" of the small sunspot while the peak indicates the apparent height of the small "light-bridges" of granular features projecting into the sunspot. The measured height is between 200 and 450 km with an average of about 300 km and an uncertainty of 50 km. The image was analysed by Dr. Bruce Lites of the High Altitude Observatory of the National Center for Atmospheric Research, Boulder, Colorado, and is included in a paper submitted for peer review to the journal 'Solar Physics'.

2a. Small sunspot and faculae near the limb
The color of the image has been added in processing
Full Image: 3264 x 2379 Pixels, 3.6MB
Image of a solar active region taken on 06-June-2003 near the eastern limb of the Sun at heliographic coordinates of N4 E47 degrees. The limb is towards the upper left of the image. The tick marks are 1000 km apart. The blue circle shows the equivalent diameter of the Earth. The image is a filtergram taken in 430 nm "G-band" light at the Swedish 1-meter Solar Telescope on the island of La Palma, Spain. Here again we see the distinctly three-dimensional character of the photosphere near the limb, particularly in the region around the sunspot. Faculae also appear as high-contrast bright "walls" on some of the granules. The facular bright structures range in length from about 150 to 400 km. The image was taken by Dr. Luc Rouppe van der Voort of the Institute for Theoretical Astrophysics of the Univeristy of Oslo, Norway, and processed by Dr. Mats G. Löfdahl of the Institute for Solar Physics of the Royal Swedish Academy of Sciences and Dr. Tom Berger of the Lockheed Martin Solar and Astrophysics Lab, Palo Alto, California.

2b. Magnetic fields of the small sunspot and faculae near the limb
Full Image: 3264 x 2379 Pixels, 2.5 MB
A "magnetogram" image of the G-band region shown in the previous figure. The tick marks are 1000 km apart. The blue circle shows the equivalent diameter of the Earth. A magnetogram is an image of the magnetic field of the Sun taken in a spectral line of iron (Fe) at about 630 nm. Positive polarity magnetic fields show up as white structures in the images, negative polarity fields show up as black, and gray areas are regions of low field strength. The magnetogram reveals magnetic structures as small as 150 km in size and about 0.15 Tesla in field strength. It confirms that the bright faculae seen in the G-band image are exactly aligned with the magnetic fields. Dark gaps in the facular brightenings correspond exactly to gaps of decreased magnetic field in the magnetogram. This image is the highest resolution magnetogram ever measured near the solar limb. Studies of such magnetograms will greatly expand our knowledge of how convection and magnetic fields interact on the Sun. The magnetogram images were taken by Dr. Luc Rouppe van der Voort of the Institute for Theoretical Astrophysics of the Univeristy of Oslo, Norway, and processed by Dr. Mats G. Löfdahl of the Institute for Solar Physics of the Royal Swedish Academy of Sciences and Dr. Tom Berger of the Lockheed Martin Solar and Astrophysics Lab, Palo Alto, California.

3. Granulation, sunspots, and small magnetic elements near disk center
The color of the image has been added in processing
Full Image3312 x 2400 Pixels, 5.4MB
Image of a solar active region taken on 13-May-2003 near the center of the solar disk at heliographic coordinates N10 E15 degrees. The tick marks are 1000 km apart. The image is a filtergram taken in 430 nm "G-band" light at the Swedish 1-meter Solar Telescope on the island of La Palma, Spain. The image shows that at disk center small magnetic elements show up as compact bright features in the dark lanes between granules. Their size is about 100 km in diameter: significantly smaller than the facular bright structures seen in the limbward images above. How magnetic fields go from being small bright "dots" at disk center to large extended faculae near the limb has long been a mystery in solar physics. The image was taken by Dr. Tom Berger of the Lockheed Martin Solar and Astrophysics Lab, Palo Alto, California.

4. Illustration of the perspective effect
Graphic illustration of how a square "bump" appears from directly above (left) and from an angle (right). Looking at granulation on the Sun is apparently similar: looking at disk center as in the image above we see only the relatively flat tops of the granules; looking at an angle near the limb with high resolution we can now see the three-dimensional aspects of granulation and faculae.

5. Movie comparing G-band and Magnetogram images of a sunspot

Movie QuickTime, 54MB
The color of the image has been added in processing

The movie zooms into the sunspot shown in the 06-June-2003 G-band image above and then blinks between it and the simultaneous magnetogram to show the alignment of sunspot structures and the magnetic field down to scales of 150 km. The movie was made on a Macintosh G4 computer using FinalCut Pro. Digital video editing tools are becoming commonplace in the exploration of large solar physics image datasets. The movie was produced by Dr. Alan Title of the Lockheed Martin Solar and Astrophysics Lab, Palo Alto, California.

6. Movie comparing G-band and Magnetogram images of faculae

Movie QuickTime, 43MB
The color of the image has been added in processing

The movie zooms into an area of faculae shown in the 06-June-2003 G-band image shown above and then blinks between it and the simultaneous magnetogram to show the alignment of facular bright points and the magnetic field down to scales of 150 km. There is some residual distortion between the G-band and magnetogram images because the images are not exactly simultaneous and the Earth's atmospheric turbulence distorts the images slightly differently. The movie was produced by Dr. Alan Title of the Lockheed Martin Solar and Astrophysics Lab, Palo Alto, California.


More Information
For further information contact Buddy Nelson:
Voice: (510) 797-0349
Pager: (888) 916-1797
buddynelson@mac.com

For further information on the Swedish 1-meter Solar Telescope please go to http://www.solarphysics.kva.se

For further information on the Institute of Theoretical Astrophysics of the University of Oslo please go to http://www.astro.uio.no

The National Center for Atmospheric Research High Altitude Observatory website is located at http://www.hao.ucar.edu

The Lockheed Martin Solar and Astrophysics Laboratory main website is located at http://www.lmsal.com/

TRACE is a NASA SMEX satellite operated at the NASA Goddard Space Flight Center by NASA and Lockheed Martin.

This work was partially funded by the Michelson Vector Magnetograph contract of the NASA Marshall Space Flight Center to Lockheed Martin: NAS8-98032. The SST is located at the Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, Spain.


Website maintained by David Schiff schiff@lmsal.com