Sunday, July 13, 2008

Where Have all the Sunspots Gone?

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Last month I wrote:


From this story on where they talk about the opposing views solar scientists have for cycle 24 they offer some opinions. NOAA Space Environment Center scientist Douglas Biesecker, who chaired the panel, said in a statement:

[…] despite the panel’s division on the Sun cycle’s intensity, all members have a high confidence that the season will begin in March 2008.


We are halfway through March, and the sun has been very quiet, Ap magnetic index remains low, sunspots are zilch, all we have is a bit of solar wind from the occasional coronal hole.

The forecast from SWPC is flatness for the 10.7cm band:


This is the one that worries me though, as I’ve pointed out before, we have that step function (or discontinuity) in 2005 (see red arrows) which gives the impression that something just “switched off” in the solar magnetic dynamo:


Additionally, the sunspot forecast from SWPC calls for sunspot numbers to be very low for the remainder of 2008, which seems to put a kibosh on the consensus formed by NASA’s convened solar scientist panel which made that prediction of “…the season will begin in March 2008” uttered by panel chair Biesecker quoted above.


We live in interesting times.


January 2008

The first sunspot group of the new solar cycle, AR 981, was seen on the 5th as two sunspots in a group of type Axx at 28°N/249°. These were not seen on the following day. The only other group seen from the eight observations made during the month was on the 30th - AR 982 at 9°S/247° was from the old cycle as was seen as a collection of 5 sunspots of type Bxo.

The six observations made between the 6th and 27th all showed a blank disk.

Hydrogen Alpha:

Prominences seen on the 5th, 6th and 13th were not particularly striking. On the 27th an arch type prominence was seen on the SE limb while further towards the equator a bright but not particularly tall prominence was seen. By the 30th quite long filaments were seen on the eastern part of the disk together with plage around AR 982. In fact these filaments appeared to be pointing towards this active area. Also on the 30th another small but bright prominence was seen near the equator on the eastern limb.

February 2008

On the 2nd AR 982 was observed under poor seeing conditions an Axx group consisting of two small sunspots. On the 9th a short-lived Bxo group was seen at 3°N/118° (it was not seen on the preceding or following days and was not reported by NOAA). The other 5 observations made during the month showed blank disks.

Hydrogen Alpha:

5 Hα observations were made during the month. The most striking prominences seen were on the 10th on the W limb and on the 16th & 17th on the NE limb. Both were of the hedgerow type. No filaments were seen.

March 2008

No sunspots were seen until the observation of the 24th when the Dsc group of AR 987 at 7°S/261° and the Cso group of AR 988 at 7°S/236° were both seen in eastern hemisphere. By the 29th AR 987 had reduced in size slightly from 90 to 50 millionths while AR 988 had developed into an Eao group with an area of 140 millionths. These two groups were joined by a third group, AR 989, at 11°S/207°. On the 31st AR 987 had reduced to a single Hsx spot approaching the western limb, AR 988 had lost its following penumbral spot although its area had increased to 190 millionths and AR 989 was no longer visible having decayed on the disk.

Hydrogen Alpha:

From the 7 Hα observations made during the month the most striking prominences seen were on the 21st when four were visible, three on the eastern limb and one on the western. One of these consisted of arches. Filaments were much more visible than during recent months, especially at the start and end of the month. On the 2nd, for example, four regions of filaments were seen while on the 24th and 29th a long filament was seen to the south of AR 988. A flare was seen during a short observing session from 14h 40m to 14h 50m on the 24th within AR 988. Plage was seen around all three active regions of AR 987, AR 988 and AR 989 on the 29th.

April 2008

AR 987 and AR 988 were still visible on the 1st although AR 987 was an Axx spot close to the western limb and it had rotated around the limb by the time of the next observation on the 3rd. AR 988 was a single Hax spot on the 1st and 3rd and it had disappeared by the 4th.

No further sunspots were seen until the observation of the 22nd when AR 992 had developed on the disk as a Bxo group at 14°N/274°. This group was seen again on the following day but not on the next observation on the 26th.

Hydrogen Alpha:

Prominence activity was quite low during the month with at most four prominences seen on any of the 15 observations – none of the prominences seen were particularly striking. Filaments were seen on the 3rd and 4th and again on the 23rd and 26th. Plage was seen around new cycle AR 990 on the 14th, 15th, 16th and 17th.

May 2008

On two small sunspot groups were seen during the month. AR 994 was seen at 12°S/311° on the 18th as a Bxo group and 19th as an Axx spot. The other group was AR 996 also on the 19th at 7°N/258° as a Bxo group. The other 18 observations made during the month, from the 1st to 14th, 22nd to 24th and the 31st all showed blank disks.

Hydrogen Alpha:

A dynamic prominence was seen on the 14th on the SE limb. At 07h15m it was seen as a tower of hydrogen that turned through a right angle and then fall back towards the limb. When observing later the same day at 16h45m, this prominence had changed shape to appear more like a wind sock and it was changing shape over the timescale of a few minutes with regions of hydrogen appearing and disappearing. Another active prominence was seen on the 14th also on the SE limb but not as bright on the above dynamic prominence.

Plage was seen around AR 994 on the 18th and 19th and around AR 996 on the 18th, 19th and 22nd.