Hi Kurt, Roger Fry was the person who brought the clubs h-alpha, the changes we saw could very well have been from changing the filter to o "off-band" use. I would direct people to this web page http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?SOHO+prominence , it is search of SOHO images over the years and is very educational. I have found alot of confusion from amateurs about prominences, flares, and CME's. A typical prominence will last up to a month, I have found them hard to see much change in morphology over any time period other more than 8 hours of observation. They do happen, but most often around solar max, and are more "energetic" phenoms. http//antwrp.gsfc.nasa.gov/apod/ap00403.html I would be interested to hear from other H-Alpha users experience with prominence observations.
8 or 9 scopes showed up for this sun party, including Roger Butz with the SLAS H-alpha scope, several PST's, a SolarMax 90, a double-stack SolarMax and a Bader filmed 8" Dob.
On today's Sun, sunspot 960 - a group of about 6 to 8 individual spots, is rising just south of the solar equator on the eastern rim. Sunspot group 960 now appears to qualify as a full-blown active region.
A Cloudy-Nights H-alpha photo from 6/2 by "badsnoopy": http://www.cloudynights.com/ubbthreads/attachments/1639966-M006%20stack%20co...
Today's Mauna Loa H-alpha pic: http://www.sec.noaa.gov/SWN/mlso_halpha.jpg
Cai-Uso Wohler's image from Spaceweather.com: http://spaceweather.com/swpod2007/02jun07/Cai-Uso-Wohler-Ha2007-06-02--06h50...
See other great images of this group at http://spaceweather.com/
In the 8" whitelight dob, the sunspot group was particularly striking. I recommend to everyone to take a quick white light peak at this group.
One spot had a large penumbra with a second smaller spot inside the penumbra. This can be an indication of potentially flare proceeding area. In white-light, a dark filament could be seen south of the group (this is detail that could not be seen in the online images cited above). The dark filament marks the boundary between a polarity change on the surface of the Sun. (The Sun is polypoid - this is it has a north and a south magnetic poles, but is also has many large regions of its surface where polarity is either plus or minus. These are generated by large meso-sized convection plumes beneath the photosphere's surface. The dark filaments are an indicator of those polarity boundaries.)
In H-alpha, the sunpots were ill-defined compared to the white-light view. But the associated bright active region zone to the east of the leading dark sunspot is particularly visible in the H-alpha view.
Sunspot 960 and its associated active region illustrate two of the Sun's spot cycles. Sunspots tend to emerge in pairs of opposite polarity aligned in a roughly east-west line. The leading spot has the same polarity as that hemisphere. The solar hemispheres have opposite polarities that switch every eleven years. On one-half of the Sun's disk, dark sunspots _lead_ their associated active regions across the face of the disk and have the same polarity as north or south hemisphere. This situation is seen in Sunspot group 960 - the dark sunspots _lead_ the associated bright active region. In the opposite hemisphere of opposite polarity, the bright active regions _lead_ their associated dark sunspots across the face of the solar disk. The polarity of the sunspots and the active regions are reversed in each hemisphere. The leader spots have the same polarity as their hemisphere; follower spots have the opposite polarity of their hemisphere.
As situation opposite to sunspot 960 - following dark spots and leading active regions, can be seen in British amateur Maurice Gavin's June 9, 2006 PST and PST-Ca images -
http://www.cloudynights.com/photopost/data/500/11401prom060529.jpg
In one model of the 11 year collapse of the Sun's magnetic fields, the follower-opposite polarity spots are preferentially swept to higher latitudes as a spot group disperses (because they are magnetically attracted to the opposite polarity poles). These opposite polarity spots cancel out part of the relatively weak polarity field at the north and south solar poles. As the number of spots increase towards the end of each eleven year half cycle, the opposite polarity spots eventually overwhelm polarity at the poles, triggering a field collapse. After the polarity reversal, the order of leaders and followers between active regions and dark sunspots reverses. Thus, a complete solar cycle is once every 22 years - not 11 years.
Today, on the setting northwestern limb were two large prominences - a typical arch prominence and a nearby inverted Y shaped prominence/coronal streamer. A similar inverted Y shaped feature is shown in this April 6, 2005 image by Maurice Gavin -
http://home.freeuk.com/m.gavin/prom050328_mg.jpg
In these inverted Y features, some of the magnetic force lines connect in a circle where the "donut hole" of the Y is formed. Others move up of the Sun and meet higher in the low transition zone into the corona. Somehow, these lines trap and support relatively dense and cool 10,000 K photosphere gases higher up in the transition-coronal zone that may be 1,000,000 K in temperature. How this occurs is not completely understood. There is contradiction between a physical structure existing at 10,000 K in a 1,000,000 K bath for several hours. Its kinda like throwing an ice cube into a boiling pot of water and it takes a day for the ice cube to melt. How this occurs is a mystery.
Roger Butz and Rodger Fry mentioned that while watching these prominences over 1 and a half hours, they could see physical changes in their appearance.
Many thanks to Dan Turner, whose recommendation to read Jack Zirker's _Journey from the Center of the Sun_ (Cambridge Press 2000) has opened for me just what a wild, complicated our poorly understood Sun really is. I'm still learning, but I recommend this book as a good starting point on relatively current solar research and as a good general read for any cloudy night.
- Kurt
P.S. - Also of interest to PST owner's is Maurice's template for a PST sunscreen from cardstock.
http://home.freeuk.com/m.gavin/solatrax.htm
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