Here is visual backup material for the AAS/SPD press conference of the same name; at the bottom is a copy of the initial press release. This page will remain accessible until 1-July-2009. Each web-sized image is a hyperlink to a higher-resolution copy of itself.
1. solar diagram
This diagram of the Sun's internal structure shows the Sun's major parts, including the jet streams that are the subject of today's telecon. The jet streams extend deep into the Sun, to the base of the solar convective zone.
2. Solar movie
(click image for movie) This movie reveals motions of the Sun's interior as measured with helioseismology on data from GONG and SOHO/MDI. East to west motion is color coded: blue is slow, red is fast. A red band in the outer third of the Sun moves slowly down from near each pole toward the equator; that band is the jet stream that is associated with sunpot emergence and the solar cycle. As of early 2009 the Cycle 24 jet streams have just reached N/S 22 degrees latitude, and new sunspots are beginning to emerge.
3. 7000 km down
This diagram shows east-to-west motion speed versus latitude, as it evolves year to year at a depth of 4000 miles (7000 km) in the solar interior, as derived from helioseismology observations by GONG and SOHO?MDI. The diagonal yellow bands are the "torsional oscillation" jet streams inside the Sun. The streams are associated with the solar activity cycle. The flow for the previous cycle (#23) can be seen in yellow at the left side of the picture, while the flow for the next cycle (#24) is visible in yellow at the right side of the image. The streams for Cycle 24 have migrated slower than those for Cycle 23. The bottom of the yellow band is currently at the critical latitude of N/S 22 degrees (mid 2009).
4. 7000 km deep overlay
This diagram shows east-to-west motion like (2) above, but overlain on the surface pattern of sunspots and solar activity high above. The dashed diagonal lines show the slope (in degrees of latitude per year) of the Cycle 23 motion. The Cycle 24 motion has a shallower slope, requiring one extra year compared to Cycle 23 to reach the critical latitude of 22 degrees. The Cycle 24 stream is just now reaching the critical latitude, and faint signs of sunspot activity can be seen in the northern hemisphere at right. This heralds the start of a new solar cycle.
A visible light image of the active Sun. Sunspots emerge in a pair of narrow latitude bands associated with the "torsional oscillation" jet streams. When the streams, marching toward the equator, reach 22 degrees latitude, new sunspots begin to appear.
This "butterfly diagram" shows number and position of sunspots for many solar cycles. The current long minimum is unusual but not unprecedented. The new solar cycle (#24) is just beginning to appear at far right.
June 16, 2009 Contact: Craig DeForest AAS/SPD Press Officer +1 303-641-5769 AAS/SPD PRESS CONFERENCE, WEDNESDAY, JUNE 17, 2009: SONOGRAMS OF THE SUN EXPLAIN MYSTERY OF THE MISSING SUNSPOTS EDITORS: Please do not post or publish the information on press-conference access for journalists. **Please note the embargo for 12:30 p.m. MDT, Wednesday, June 17, 2009.** Below is a press release that relates to the press conference "New Insight into the Sun's Mysterious Quiet Period" at 12:30 p.m. MDT (2:30 p.m. EDT) on Wednesday, June 17, 2009, at the triennial standalone meeting of the Solar Physics Division of the American Astronomical Society in Boulder, Colorado. Also included is information on how off-site reporters can participate in the briefing via telephone and/or Internet. PRESS CONFERENCE ACCESS FOR JOURNALISTS Audio Conference Call: Toll-free calls (from within the U.S.), dial 1-866-606-4698 International calls, e-mail firstname.lastname@example.org for access When prompted, enter passcode 7976073 Internet Audio/Visual access: Point your web browser to http://spd.boulder.swri.edu/solar_mystery for access to visual material that will be used during the press conference. (The content will be made available at 12:00 pm MDT, Wednesday, June 17, 2009.) To ask questions during the conference call, please wait until prompted by the chair of the briefing, or (to ensure that your question will be taken) e-mail it to email@example.com during the briefing. The press conference will not be archived. PRESS RELEASE Forwarding of the following release does not imply endorsement by the American Astronomical Society. EMBARGOED UNTIL: 12:30 .m. MDT (2:30 p.m. EDT) Wednesday, June 17, 2009 Press contact: Dr. Craig DeForest SPD Press Officer firstname.lastname@example.org +1 303-641-5769 Scientific contacts: Dr. Frank Hill National Solar Observatory email@example.com +1 520-318-8138 Dr. Rachel Howe National Solar Observatory firstname.lastname@example.org +1 520-318-8573 Dr. Dean Pesnell NASA/GSFC William.D.Pesnell@nasa.gov +1 301-286-4009 SONOGRAMS OF THE SUN EXPLAIN MYSTERY OF THE MISSING SUNSPOTS Boulder, Colorado -- Scientists from the National Solar Observatory (NSO) in Tucson, Arizona, have discovered that a solar jet stream deep inside the Sun is migrating slower than usual through the star's interior, giving rise to the current lack of sunspots and low solar activity, according to work being presented this week at the meeting of the Solar Physics Division of the American Astronomical Society (AAS/SPD). The Sun normally undergoes an eleven-year cycle of magnetic activity related to sunspots, solar flares, and the interplanetary storms called "CMEs". The current "solar minimum" quiet period has been unusually long and deep, confounding scientists who hope to understand the origins of space weather and the Sun's magnetic field. Drs. Rachel Howe and Frank Hill, both of the NSO, used long-term observations from the NSO's Global Oscillation Network Group (GONG) facility to detect and track an east-to-west jet stream, known as the "torsional oscillation", at depths of ~1,000 to 7,000 km below the surface of the Sun. The Sun generates new jet streams near its poles every 11 years; the streams migrate slowly, over a period of 17 years, to the equator, and are associated with the production of sunspots once they reach a critical latitude of 22 degrees. Howe and Hill found that the stream associated with the new solar cycle has moved sluggishly, taking three years to cover a 10 degree range in latitude compared to two years for the last solar cycle, but has now reached the critical latitude. The current solar minimum has become so long and deep, some scientists have speculated the Sun might enter a long period with no sunspot activity at all. The new result both shows that the Sun's internal magnetic dynamo continues to operate, and heralds the beginning of a new cycle of solar activity. "It is exciting to see", said Dr. Hill, "that just as this sluggish stream reaches the usual active latitude of 22 degrees, a year late, we finally begin to see new groups of sunspots emerging at the new active latitude." Since the current minimum is now one year longer than usual, Howe and Hill conclude that the extended solar minimum phase may have resulted from the slower migration of the flow. GONG and its sister instrument SOHO/MDI measure sound waves on the surface of the Sun. Scientists can then use the sound waves to probe structures deep in the interior of the star, in a process analogous to a sonogram in a medical office. "Using the global sound wave inversions, we have been able to reveal the intimate connection between subtle changes in the Sun's interior and the sunspot cycle on its surface," said Hill. "This is an important piece of the solar activity puzzle," said Dr. Dean Pesnell, of NASA's Goddard Space Flight Center. "It shows how flows inside the Sun are related to the creation of solar activity and how the timing of the solar cycle might be produced. None of the forecasting research groups predicted the current long extended delay in the new cycle. There is a lot more to learn in order to understand how the Sun creates magnetic fields." The new science of helioseismology, enabled by instruments such as the ground- based GONG, the Michelson Doppler Imager aboard the SOHO spacecraft, and NASA's planned Solar Dynamics Observatory, has revolutionized understanding of the solar interior. "While the surface effects of the Sun's torsional oscillations have been observed for some time, understanding of the dynamo and the origin of sunspots depend on measurements of the solar interior that are only possible with helioseismic techniques", said Hill. -------------------------------------------------------------------------- If you do not wish to receive press releases that are forwarded to the news media by the American Astronomical Society, please unsubscribe by replying accordingly to any incoming press release, or send e-mail to email@example.com. Requests for referrals to experts on astronomy and space exploration should be sent to the same address. Rick Fienberg, AAS Deputy Press Officer: firstname.lastname@example.org, telephone 1-857-891-5649.
An additional science contact named in the conference was:
Jesper Schou, Stanford University