Penumbral Waves!

Late November Sun

My last solar observing day for 2011 was November 25, just 28 days from the winter solstice. The Sun manages a maximum altitude of only about 30 degrees above the horizon at this time of year and is mostly hidden behind trees and rooftops from my observing spot. Even though a small two hour window between trees still exists, the colder weather discourages me. My tolerance for winter observing has been severely diminished by 33 freezing years spent in the unheated Randolph College observatory. I probably won't observe again until March or April.

It was unseasonably warm and pleasant on November 25, so I made the most of my brief view between trees. First, look at this mosaic of sunspots and filaments:

Sunspot 1358(L) and the 1356 group(R) (Click for full detail)

Moving across the Sun to the right of the mosaic above brings sunspot 1355 into view to the right of the 1356 group along with a nice set of filaments:

Sunspot group 1356(L) and sunspot 1355(R) (Click for full detail)

After completing the still images I tried, once again, to make some movies. Seeing conditions were fairly good in spite of occasional wind. Once again I failed to record any extremely dramatic eruptions, but I did manage to capture examples of a phenomenon known as penumbral waves. The first movie below shows 60 minutes of action in sunspot group 1356 from 12:16 PM to 1:16 PM EST. (Be patient until the movie loads and plays properly.) An eruption spewing out a gas plume was already in progress on the far left as recording began. Focus attention on the largest dark sunspot umbra and the lighter grey penumbra surrounding it. You will notice circular ripples heading out from the center like waves from a stone dropped in a pond. These are called penumbral waves.

Penumbra waves were also visible in sunspot 1355 below during the same time period:

Graphs and Laughs

I'm a quantitative guy!

Those who know me laugh and roll their eyes at my habit of measuring, counting, and graphing all sorts of things. For instance:

• In 2003 I ate 29 boxes of corn flakes.
• Over the course of several years I've picked up 20,526 walnuts from my back lawn before finally deciding to remove the annoying walnut trees.
• I once got 69 shaves from one razor blade.
• During my academic career I spent 439 nights, more than a year of nights, at the college observatory measuring variable stars.

I find these trivial facts strangely amusing. Let's see. If I've been eating 29 boxes of corn flakes a year ... in the last 30 years ... I've consumed 870 boxes! Maybe I should order corn flakes by the truckload. Geez! A lot of corn flakes have gone through my system!

I've accumulated a good number of running miles over the years, 43,755 miles to be exact. Now, like an aging machine, my body is beginning to creak, clank, and groan. Here's a record of my yearly running mileage since I started keeping records in 1972. (Incidentally, 43,755 miles is nothing compared to many lifetime runners who have gone three or four times this far!) This year I've managed to run only 581 miles so far. A knee injury is holding me back at the moment.

Note the recent decline and the optimistic continuation to 2020. (click to enlarge)

On the other hand, I've been more durable on my road bike. I've accumulated 36,576 road biking miles since 1987.

Biking mileage hasn't declined in recent years! I'm not dead yet! (click to enlarge)

Compare the graphs for years 1988 and 1989 when I could hardly run at all due to running injuries. I switched to mostly biking and recorded big bike mileage then. This year has been my second best biking mileage year ever at 2,722 miles so far.

Every year I fight a constant battle to maintain an athletic weight of 147 pounds. Every year I lose the battle during the winter months when I can't burn enough calories on my bike. For example, look at my weight last year in 2010:

The year begins with the usual bloat from the preceding 2009 Thanksgiving and Christmas. Weight starts to drop as I recover, but then, classes begin. Almost immediately my schedule and diet become chaotic as stress begins building. It's winter and there's no time to bike. Also, I can no longer run far enough to burn significant calories. So the sad inevitable weight increase proceeds through February and March peaking at over 158 disastrous gut-busting pounds in mid-April. I recover very briefly before the upward slide starts again. At last April ends, classes end, weather warms, my schedule loosens, and I get on the bike. Immediately my weight starts dropping as I get control of my life again. By the end of August I've reached my goal of 147 pounds. Unfortunately, biking gets harder as the days shorten and temperatures drop. I'm still near 147 in early November when I'm rocked by a 48-hour virus. The illness really depletes me. Notice what happens at Thanksgiving! Yikes! Big dinners, no biking, trays of caloric treat bombs sprinkled around the house, and more calories at Christmas lead to immediate weight gain. But I end the year at 149 pounds, roughly 7 pounds better than the previous year's 156 pounds.

How are things going this year? Although no longer teaching classes after retirement, I still gained weight during the winter because calories in exceeded calories out. But good news is recorded in the 2011 graph below.

I reached my goal weight of 147 at the beginning of July in 2011 instead of at the end of August as in 2010. Now, in early December, I've so far managed to avoid the usual holiday weight gain. It's after Thanksgiving and I'm still good! This year I am absolutely determined to stay near 147 until next spring when I get back on the bike again. Then let snacking begin!

Best Mosaic Yet!

November 8, 2011

A multitude of interesting solar features were displayed on November 8th. Several sunspots, filaments, and prominences were visible and there were periods of good seeing during my three hour observing window.

Sunspot 1338 (Click for full detail)

 Some interesting dark filaments near sunspot 1340:

Sunspot 1340 with filaments (Click for full detail)

Nine separate overlapping images were blended together to produce the image below, the best mosaic I've been able to produce so far. You really need to view this image full size to appreciate all the detail present: a huge prominence on the upper left, two spectacular arcing filaments, bright white active areas, and four sunspots! The bottom part of the big prominence on the upper left curves down onto the solar disk where it appears as a broad dim filament. I'm really excited about this image!

L to R: Sunspots 1343, 1341, 1342 and 1339 (Click for full detail)

For 25 minutes from 12:41 PM to 1:06 PM EST the seeing was good enough to record some activity in the upper left region of the mosaic above. After 1:06 seeing drastically deteriorated and further imaging was futile. What a shame! Another 30 minutes or so would have revealed even more curling, undulating gas plumes and waving filaments. Please be patient while the movie loads and begins to play smoothly.

Giant Sunspot

Huge Sunspot Appears

Observing opportunities from my driveway diminish as autumn  proceeds. The Sun disappears behind chimneys and trees on its lower, ever-shortening arc across the sky. Only a few hours were available November 2 to image giant sunspot 1339 emerging around the Sun's rim.

Left:Sunspot 1339; Right: small sunspots 1337 and 1336 (Click for full detail)

Notice the flame-like gas plume erupting toward the rim from an active area within the 1339 complex on the left above. During a brief 25-minute interval from 2:44 PM to 3:09 PM EDT on November 2, 2011 I was able to record some of this eruption in the following movie:

Unfortunately, the movie ended prematurely when the Sun passed behind an annoying tree. I wish the action could have continued longer!

Three days later, on November 5, sunspot 1339 had been carried further toward the center of the Sun's disk. Although seeing conditions were mostly terrible on November 5, I was able to get one presentable image of 1339 showing its complicated structure more clearly than the image above.

Sunspot 1339 on November 5 (Click for full detail)

Three days later, on November 8, the seeing was better and sunspot 1339 now looked like this:

Sunspot 1339 on November 8 (Click for full detail)

 Notice the changes in 1339 over the three day interval from November 5 to November 8. The elongated sunspot on the far left seems to be fading out while the largest sunspot on the right has condensed a bit and is no longer split in two. More images from November 8 will appear in next week's post.

Nice Filament

Best Filament Image So Far

Filaments are somewhat like clouds above the solar chromosphere. They are cooler than their immediate surroundings and cooler than some of the chromosphere below. This relative coolness makes them appear dark against the background solar disk. Filaments are temporarily held in place by magnetic fields. The first image below is the best image I've yet captured of a filament, in this case a hook-shaped one beneath a patchwork pattern of bright activity:

Hook-shaped filament imaged on October 25, 2011 (Click for full detail)

When a filament is seen on the rim of the Sun it is called a prominence. The image above shows the "top view" of a prominence. The following image shows the "side view" of a (different) prominence with sunspot 1327 also visible.

Sunspot 1327 with prominences on the right (Click for full detail)

The original goal on October 25th was to use a Mylar-filtered Celestron-8 telescope mounted for the first time on my Ioptron Mini Tower Pro. I hoped to image the same sunspot in both the photosphere (visible surface of the Sun) and the chromosphere (layer just above the photosphere). I was curious to see if the Celestron-8 would capture any granulation (evidence of rising and falling gases) in the solar photosphere. Unfortunately, the seeing was not good enough to reveal detailed granulation. Intermittent breezes buffeted the telescope and images wavered and danced in the video display. Below are the best results for my photosphere/chromosphere comparison for sunspot 1330. First, the Celestron-8 prime focus photosphere image:

Sunspot 1330 with photospheric granulation barely visible (Click for full detail)

Here is an image of the same sunspot 1330 taken with the Lunt 100mm H-alpha telescope showing sunspot 1330 in the chromosphere:

Sunspot 1330 in the chromosphere (Click for full detail)

Here's a blinking comparison between the Sun's photosphere (purple) and chromosphere (red):

Purple to red moves outward away from the Sun's center.

Multiple Sunspot Movies

Four Sunspots In Action

The movies below were recorded on October 16th. They show 64 minutes of activity between 10:00 AM and 11:04 AM EDT in the four sunspots shown in this (colorized) still image.

Diagonally bottom to top: Sunspots 1314, 1319, 1316, 1317.

The movie of the entire scene above was too large to upload. Instead, I've broken it up into two smaller pieces. Both movies take a few minutes to load properly, so please be patient. In the upper right portion of the first movie a gas plume eruption is already in progress near sunspot 1317 at the movie's start, so the eruption seems to start instantaneously:

 The remaining two sunspots featured bright flare-ups as seen below:

Sunspot 1319 at top right has an eruption recorded here just about 20 minutes before the recording shown in my previous post. Bright eruptions also occur in sunspot 1314 at lower left, including one outburst from the edge of the dark umbra. The other flame-like explosion from 1314 seems to push gases along a c-shaped arc in the lower left corner.

Sunspot 1319 Movie

Just Missed An Energy Flare

This is one of the movies I promised in my last post. The movie begins with some bright white energetic eruptions already in progress. The eruptions fade away while gases swirl. Too bad I didn't start recording about 20 minutes sooner! Then I could have captured both the rise and fall of the eruption. One of these days I'll get lucky and timing will be better. 

Here is a still image of sunspot 1319 showing its complicated structure and some areas of bright emission.

Sunspot 1319 in center. Sunspot neighbors above and below. (Click for full detail.)

The movie below shows 33 minutes of activity in sunspot 1319 from 11:22 AM to 11:55 AM EDT on October 16, 2011. It takes a while for the movie to load and play at normal speed, so please be patient. 

Even though I took meticulous care in the manual alignment of each frame in this movie, there is still a bit of jiggle in the final result. Apparently it takes only a few slightly misaligned frames to cause the annoying effect.

Watch this movie for a few minutes. You'll notice the hot, white, energetic interior underneath the cooler, darker, continuously churning gas plumes above. It looks like the hot white stuff wants to break out from the Sun. It ominously tests its bonds by brightening in several locations, including a winding network in the lower left.

I wish I had recorded the action for more than 33 minutes. What happened next? In my next post I'll have a 64-minute movie including this sunspot along with some others nearby. Maybe this 64-minute movie will capture more action!

Splendid Sun!

October 16, 2011

Solar imaging improves! Cloudless sky and pleasantly cool temperature made observing comfortable on October 16th. Absolute perfection is hard to achieve, however. It was a bit breezy, sometimes enough to shake the telescope. Nevertheless, I was able to get my best whole disk solar image so far. The following image is a mosaic of seven individual images, each made at the prime focus of my Lunt 100mm h-alpha telescope with a DMK41 camera. The Sun's disk contained a good number of sunspots, dark filaments, and even a few bright white eruptions! Too bad there weren't a few more dramatic prominences. Still, this is the kind of image I hoped to achieve when I bought my solar scope.

(Click for full detail.)

After capturing images at prime focus I used a 2X Barlow lens to magnify some of the sunspots. Here is an image of sunspot 1312, the one at the bottom of the whole disk image near the prominence.

Sunspot 1312 and prominence (Click for full detail.)

Finally, here is an image of the two sunspots slightly below and to the left of the disk center.

Sunspot 1314 bottom left, sunspot 1319 top center (Click for full detail.)

Sunspot 1319 at top center had a beautiful complicated structure seething with bright white energetic eruptions. I recorded 34 minutes of activity in sunspot 1319 and hope to make a good movie for my next post a few days from now.

I also recorded 60 minutes of activity at prime focus showing activity in more than one sunspot. That movie will take much longer to construct and will not appear for a while.

In this productive observing session I recorded 112 videos, each about 27 seconds long. (This amounts to 51 GB of data! Thank goodness for big hard drives!) Each video contains 400 still frames. The 400 somewhat blurry still frames in each video get combined by magical Registax6 software to produce one single detailed still image. Then I enhance and colorize these 112 detailed still images to make movies, mosaics, or individual images. I'm really enjoying this!

October 5th Sun Movie

Beautiful Clear Sky!

A spectacular giant erupting sunspot moved across the Sun's disk in late September. Uncooperative completely cloudy weather here in Virginia prevented observation of the fireworks. A stretch of excellent weather arrived soon after with mild temperature, low humidity, and not one cloud in the sky. Several sunspots were present on October 5. Here is sunspot 1309:

Sunspot 1309 with sunspot 1312 in upper left. (Click for full detail.)

Changing the view slightly shows sunspot 1312 on the left and 1309 on the right with spicules along the Sun's rim:

Sunspots 1312 and 1309 (Click for full detail.)

Here's another pair of sunspots on the opposite side of the Sun:

Small sunspot 1306 on left, larger spot 1305 on right. (Click for full detail.)

I spent most of the observing session trying to record a small eruption near sunspot 1313. Here's an image of emerging sunspot 1313:

Sunspot 1313 is in the upper left. (Click for full detail.)

One 400-frame video was recorded every minute for one hour. Each video eventually produced one still frame. Hours of tedious manual alignment of these 61 still frames produced the following movie showing one hour in the life of sunspot 1313 from 11:39 AM to 12:39 PM EDT. This will take some time to load before it plays at normal speed. Please be patient!

Look at the spray of gas erupting in the upper left! Some movement is also visible along the snake-like filament on the right. Sadly, the movie continually jiggles because, even after hours of manual alignment, I could not get the individual frames perfectly aligned. Almost every feature on the Sun is continually moving, so it's hard to find fixed reference points to align. Although the dark sunspot umbra here stays fairly constant, it is small and not very distinct. The solar rim should also be a fixed feature. Unfortunately, the exact position of the rim seems to depend on the exposure settings of the camera which changed automatically as the image drifted due to imperfect tracking. In the future I need to improve image alignment.

Eclipsing Stars

Observing an eclipse of RW Geminorum

This is the final example of my not widely shared observations made at Winfree Observatory at Randolph Macon Woman's College (now called Randolph College).

A total solar eclipse, when our Moon passes in front of the Sun, is a spectacular and somewhat rare event! People travel all over the globe to watch. So far I've been fortunate to see only one total solar eclipse in my life, on July 10, 1972 on Prince Edward Island, Canada.

With C at the 1972 eclipse site on Prince Edward Island

A total solar eclipse looks roughly like the image below when viewed with ordinary binoculars during totality. Notice the pink flame-like prominences which become visible on the Sun's rim!

A view similar to what I saw from Prince Edward Island with unfiltered binoculars

As wonderful as a solar eclipse is, it must be tame compared to one star eclipsing another! Wouldn't it be amazing to watch one star pass in front of another? Actually, this happens frequently in the heavens when two stars orbit each other. These are called binary stars. If a distant planet happened to orbit a binary star, it might experience double sunsets like Luke Skywalker observed from the planet Tatooine in this memorable scene from the first Star Wars film:

There are a great number of binary stars with orbital planes oriented edge-on to our line of sight. As these stars orbit they regularly pass in front of one another and produce eclipses from our point of view. One such eclipsing binary star is called RW Geminorum (meaning the variable star system RW in the constellation Gemini). The red X locates the position of RW Geminorum in the constellation Gemini below:

(click to enlarge)

What if, from our point of view, two orbiting stars completely overlap during the orbit? The light from the system should then vary like this:

A more detailed, but somewhat different, illustration is:

Notice how the brightness curve of the binary system is flat and horizontal during the deeper primary (1st minimum) and shallower secondary (2nd minimum) eclipses. These flat and horizontal portions of the light curve happen when a smaller star fits completely in front of or behind a larger star. This is the situation for the two stars, A and B, in RW Geminorum. Brighter star A has a mass of 4.97 Solar Masses, a radius of 3.69 Solar Radii, a surface temperature of 12,390K, and a bolometric luminosity of 285.25 Solar Luminosities. Dimmer star B has a mass of 2.24 Solar Masses, a radius of 4.67 Solar Radii, a surface temperature of 6,200K, and a bolometric luminosity of 28.47 Solar Luminosities. (Bolometric means including all wavelengths of light.) During the primary eclipse of RW Geminorum the smaller diameter, brighter star A is entirely behind the larger diameter, dimmer star B. This primary eclipse totality time lasts for more than an hour.

During the fall of 2003 senior physics major, Sarah Priester (class of 2004), and I decided to observe the primary eclipse of RW Geminorum. Since the complete orbital period of RW Geminorum is 2.8654972 days, we decided there would not be enough observing time in the fall semester to capture the light curve for the entire orbit. Therefore, we set out to observe only the primary eclipse. This required about 15 hours of observing.

During October and November of 2003 we observed RW Geminorum on 3 different nights. We made 189 V-filter CCD images, one every 5 minutes during each session. The exposure times varied between 60 seconds, and 240 seconds. After many hours carefully measuring and analyzing all 189 images we obtained the light curve shown below which clearly shows the primary eclipse.

This is one of the most beautiful light curves I ever achieved at Winfree Observatory!

The vertical scale is an astronomer's (logarithmic) scale of brightness measured through a photometric green filter (also known as a visual, or V, filter). The smaller the magnitude, the brighter the star. The horizontal scale, orbital phase, is a portion of the time for a complete orbit. The time for a complete orbit is 2.8654972 days. This is 1.00 cycle. The horizontal scale runs from 0.400 (40 percent) of the orbital cycle to 0.650 (65 percent) of the orbital cycle with the center of the primary eclipse located halfway through at 0.500 (50 percent) of the orbital cycle.

The duration of the flat total eclipse portion is one hour, 22 minutes with an uncertainty of about 5 minutes. The two unfortunate gaps in the otherwise beautiful curve are caused by the annoying inability of our German equatorial telescope mount to continuously follow celestial objects as they cross the meridian. At two meridian crossings no images could be taken while the telescope slewed from one side of the pier to the other.

We didn't observe the entire eclipse continuously, rather we watched like we would watch a long movie with several intermissions! There's a good chance we were the only people on Earth observing this particular eclipse at this particular time!

Cicada Killers!

Scary Looking Bugs!

Cicada killers have infested the area along our stony driveway the past few years. These huge wasps look like scary hornets. Fortunately, they are not very aggressive. According to experts braver than I, they pack a relatively tolerable sting. A few days ago I found one apparently dead of old age.

Scary Bug! Check out the size!

Here's the side view:

Wouldn't you flinch with this buzzing around you?

During summer months air above the driveway on the side of my house is filled with these wasps as they dig burrow after burrow in dirt along the driveway. Numbers have been increasing each year. Here's one of several burrows dug into a drainage pipe in the stone wall along the driveway:

This drain pipe is now useless for drainage!

It's almost impossible to kill one of these monsters with wasp spray when they are outside the burrows. They fly too fast! Even when they temporarily land they seem unfazed by partial off-target spraying and simply fly off high into surrounding trees. My only hope is to spray into a burrow when one of them is inside. This did work once. The cicada killer got a good dose of spray. It crawled out and died soon after. Unfortunately, it's hard to know when the wasps are actually in the burrows. One evening I decided to watch one and wait holding my spray can. Back and forth it flew. Back and forth. Back and forth. It landed for 5 seconds near a burrow. My hopes rose. Then more back and forth. After about 25 minutes watching this mind-numbing behavior I gave up. Now I just spray all the burrows as they appear and hope it is doing some good. I have yet to actually observe a burrow in construction. Like a watched teapot that never boils these wasps never dig while I'm watching!

Normally, I'm happy to let bugs live outside, but these cicada killers are becoming too numerous to tolerate. The situation would soon be completely out of control without spraying. I can't mow grass without running over numerous burrows inviting attacks in response. This year they invaded every drainage pipe along my stone wall:

There are even more burrows along the other side of the driveway.

While I took these pictures Dude was puzzled as he watched from the back yard. He has a white spot on his snout from licking out a yogurt container.

Dude says: "Why is he taking pictures and not playing ball with me?"

September Sun

September 10, 2011

Cloudless sky and a quartet of sunspots invited solar observing on September 10. Pleasantly mild temperature, few bugs, and occasional gentle breeze added to the enjoyment. My new motorized focus mechanism worked flawlessly right from the start. I can now determine precise focus on my laptop screen without vibrating the telescope. Also, I FINALLY managed to eliminate extremely annoying dust from my Barlow lens. This dust was extremely hard to see until I looked at the lens surfaces with a microscope. A small hand-operated dust blower did not remove the long-settled dust, so I had to use Q-tips with alcohol. After cleaning I expected to see no dust blobs in my images, but new dust managed to get deposited in the short time it took to attach equipment to the telescope. Fortunately, I was able to blow this new dust away with the hand blower so all was well.
Here are some prominences I saw:

(Click for full detail.)

(Click for full detail.)

My original goal was to capture 60 videos of the largest sunspot, sunspot 1289, in 60 minutes to make a movie of the sunspot's activity. After much labor I did produce the movie. As Johann Kepler once said, " How small a heap of grain we have gathered from this threshing!" It so happened the sunspot was mostly inactive during the hour I chose to observe. The movie showed some movement of gases, but nothing good enough to post here. Here's underperforming sunspot 1289 on the right:

Sunspot 1289 (Click for full detail.)

The other three sunspots were not as spectacular as 1289. Here is sunspot 1290:

Sunspot 1290 (Click for full detail.)

Next is sunspot 1287:

Sunspot 1287 (Click for full detail.)

Finally, sunspot 1283 was near the Sun's limb. It emitted a spectacular flare not long before September 10. A movie of that flare would have been really beautiful. Maybe I'll get lucky some day and catch a violent eruption while I'm actually observing!

Sunspot 1283 (Click for full detail.)