Index:
The Sun.
The Sun's layers.
White light observations.
Sunspots.
H-Alpha observations.
Faculae.
Plages.
Prominences.
Flares.
The Sun:
General Information:
| Age. |
5000 million years old.
|
| Density (Water = 1). |
1.409.
|
| Mass (Earth = 1). |
333,000.
|
| Mass. |
2 x 1027 tonnes (99% of the Solar System).
|
| Escape Velocity. |
617 Km/Sec.
|
| Surface Gravity (Earth=1). |
28.
|
| Mean Apparent Magnitude. |
-26.
|
| Absolute Magnitude. |
+4 (If Sun was placed at a distance of 32.6 light years or 10 parsecs
from Earth).
|
| Spectrum Class. |
G2V.
|
| Rotation period (Siderial). |
25.38 days.
|
| Rotation period (Synodic). |
27.27 days.
|
| Diameter(At it's equator). |
886,000 miles or 1.4 million km's .
|
| Distance from Earth. | 93,000,000 miles or 149 million km's. |
| Light Distance. |
8.3 minutes.
|
It
takes 27½° earth days to rotate at is equator and about 30 days at
a latitude of 80°.As the axis of the Earth is tilted 7¼° to the perpendicular
to the Earths path,and the Earth axis is titled 23½° to this path the
Sun's axis appears at different angle's as seen from the Earth,at
different times of the year.Each pole can be as far as 26½° to the
east and then 6 months later toward the west.While the tilt first
towards use then away from us is 7¼°.The Sun is easy to see but you
must never look at the sun direct through a telescope or binoculars.You
will be blinded.
This show the positions as seen from the northern
hemisphere.
The Sun's layers:
Introduction:
In
this section I will not be talking about solar physicist in much detail
there are plenty of good book's and other web pages that do that in
great detail.The Sun is a huge globe of gas shining like others stars
because a nuclear reaction going on in the core.The Sun is made up
mostly of hydrogen(about 73.5% of its mass) and helium (about 25%
of its mass) their is a small fraction of heavier elements(about 1.5%
of its mass).Deep in the core of the Sun the nucleus of a hydrogen
atom-a proton is colliding and fusing with another hydrogen nucleus,this
happens until 4 hydrogen have become one helium atom.During this process
a small amount of mass has been destroyed,but nor has it been lost,it
has been converted into energy.Every second trillions of these processes
happen,converting 700 millions of tons of hydrogen into 695 ton of
helium, and changing 5 million tons into energy.This will power the
Sun for nearly 90% of its life.If energy(in the form of photons)
created in the Suns core was able to leave the Sun at the speed of
light it would reach the surface in 2½ seconds but because of collision
with electrons or other nucleuses as the Sun interior(called the radiative
zone.) so the journey of a photon is not an easy one.It takes
a photon 10 million years to leave the Sun then about 8 minutes to
reach the Earth.
Core:
This is the centre of the Sun were nuclear reactions take place.The
temperature here is estimated to be 15,000,000 ° K.
Radiative
Zone:
This makes up the inner two-thirds of the Sun's interior,
this transfers the energy made by the core using a radiactive process.
Convection Zone:
This makes up the outer one-third
of the Sun.It is possible that large convection cells,are heated by
the radiative zones take energy from the radiative zone to the next
area.As they cool they start to drop down were,when they reach the
radiative zone,which they are heated again and the cycle repeats.
supergranulation
:
The next layer is similar to convection cells,but
they are smaller,these pass the energy onto the bottom of the granulation.
granulation:
Even
smaller convection cells,which are seen in white light carry the energy
to the solar surface by a form of convection.
A diagram showing the Sun's interior Zones.
Photosphere:
This is the layer seen
in white light.Photosphere means "light sphere ".Its temperature is about
6000° K.It gives the Sun an apparent surface but this is merely
an illusion.What you are really seeing is a density and ionization.It
is so great the gas becomes opague.The photosphere is about 200 miles
in depth.
Chromosphere:
This is a layer above the
photosphere.The word chromosphere means "colour sphere"It can be
seen during eclipses as a red layer.It has a temperature of 4,000° K.It
is in fact a thin atmospheric layer of only about 2,400 km,although
there are no distinct boundaries above or below.
Transition Region:
The region between the corona and the chromosphere is characterized by a large rise of temperature from about 20,000° K to 2,000,000° K
Corona:
This is
the outer layer of the Suns atmosphere,above the chromosphere.Corona
means "crown" and appear white in colour.It has a temperature of over 2,000,000°
K.It can be seen during a total eclipse and using a coronagraph.
This show regions of the Sun above the photosphere.
Solar astronomy
is the observation of the Sun.The Sun holds many surprise it has many
different things to see such as sunspots which are cool regions on
the Sun they are 2000° K cooler than the surface.Sunspots are
broken into classes using letters.The first letter is the group class,the
second letter indicates the type of penumbra and the third letter
describes the distribution of spots with in the group.There is Faculae
areas of hot gas,it is best seen near the limb of the Sun.There is
one other form of detail you can see,it is granulation this is a granular
appearance seen on the Suns surface
White light Observations:
The
Solar Photospheric Detail:
Introduction:
This
section will deal with granulation,intergranular lanes and holes.Some
of these phenomena are hard to see,but they do deserve a mention.The
first one is not hard to see it does in fact help you see some of
the solar phenomena.As well as sunspots and faculae.
Limb Darkening:
This is were
the Sun appears darker near the limb than in the centre
.The reason for this is the light fades quite considerably
the further we look from the centre.The reason for this is we are
looking through more gas layers perpendicular the the
Sun's surface at the centre of the disk.Where,as we are looking diagonally
through more layer's of outer gas,so we are unable to see into the
Sun's hotter,denser and brighter layers.This makes it possible to
see facula which is invisible near the centre of the Sun.
Granulation:
Granulation
appears as a mottling(like many grains of rice)it is the plasma of
the Sun rising up from the innards of it.Each cell that makes
up the granulation is irregular shaped,it changes every 10-15 minutes.You
do not see the changes in the granulation and you need clear steady skies
to see the granulation.The word granulation comes from the latin word
"granulum" which means "grain"As far as granulation is concerned most
amateurs
will be able to see it.But it will be hard to see it in any detail,so
most observers will be unable to any research in to this phenomena.
Intergranular
lanes:
This is the name of the lane that separates each
cell of granulation.A typical distance between two granules is 1400
km's.The brightest part of a granule is 30% brighter than the intergranular
lanes this indicates that it is 400° K cooler than the plasma itself.Occasionally,the dimensions
of the intergranular lanes increase this can give rise to pores(more
detail about pores will appear later in this web page) as well as
a decrease in brightness.
Mesogranulation:
This
is associated with exploding granules,this type of granule is quite
common.When they explode they have a horizontal flow pattern which
covers a distance of just over 5,000 km's and last for 20-30 minutes.
Holes:
In
some areas the granules seem to be missing so large dark spots appear.These
should not be confused with pores as usually after a short time the
granulation cells reappear.
Supergranulation:
This
a more subtle convection that occurs on the Sun.It was first recognised
in the 1950s by A.B.Hart,from Doppler shifts of the Fraunhofer lines
which found a horizontal flow occurring over many thousands of miles.This
kind of structure lasts for a day or more.Furthermore it has an almost
horizontal flow outwards from the cell centre but it has weak upward
flow at the cell centre and downward flow at the cell boundaries.This
structure can be seen in the wing of the H-Alpha line both of which
are formed in the photosphere,as well as being seen in spectroheliograms
set at light in the weak Fraunhofer lines.
Sunspots:
Introduction:
In this section I will look at each
area that leads up to a development of a sunspot group and also
look at the different areas that a developed
sunspot has and a description will be given.
Pores:
These
are small dark spots,most last only a short time.Any that do
last on the Sun may then develop into sunspots.
Sunspots:
Sunspots
are cool areas on the Sun.They are strong magnetic features on
the Sun and are where the magnetic field on the Sun have come through
the Photosphere.They
appear darker because the sunspots are cooler and so radiate less
light.They appear as spots on
the Sun,a spot or group is made up of two main parts.
The Umbra:
The Umbra is the dark core of the spot,
if viewing using a
filter when the conditions are right brightness differences can be
seen,these
may last 10-15 minutes.
Umbral Dots:
These are brighter,blurred points in
the umbra.They are about 150-200km in diameter,and their brightness is similar to that of the photosphere.
Bright Points:
Bright points appear in the umbra.They
are brighter than umbral points,these can be seen in an 80mm telescope
if viewed directly.In the same way as umbral dots,bright points
show convection but rather more like granulation in terms of brightness.However,where
granules last on average 6 minutes,bright points are stable for several
hours.This may be due to the magnetic fields,as it has been observed
that granulation lasts longer the closer to spots it gets.Bright points
may form a network of 5°-10° and accompany light bridges in the initial
phases of their development.This has not been studied in detail.
The Penumbra:
The
Penumbra is the outside of the spot and is made up of light and dark
filament with a width of 200 km's.Many changes can be seen in a sunspot
group.Each change can be seen in just a few minutes.Sunspots come
in many shapes and sizes.
Additional Information:
Some
Sunspots will show different
shades of colour
(reds and browns have been seen)you should make notes when this happens
date/time,you must note where on the spots it happens by doing an
accurate drawing,or a photograph
would be better.
Sunspot Maximum and Minimum Cycle:
As these two term's
suggest there are times when there are plenty of sunspot's and when
they are not.This period takes about 11 year to go from sunspot minimum
to sunspot maximum,then back down to minimum again.This time can vary as
well some cycles take 9 years while it can take a little over 13½
years to do a solar cycle.The assent from minimum to maximum takes just over 4 years
while the decent back down to minimum takes 6½ years.When the Sun
is at sunspot minimum it can go many day's without any sunspots,while it is at maximum it can have as many as 20+ groups on it's disk
at any one time.When the Sun is at minimum any spots that do appear
may only last a few day's,or may be gone within a day,also the groups
do tend not to develop up to any major groups as the cycle goes on
towards maximum,so the size and types of groups increase.It is also known
that as the Sun moves through its cycle the sunspot groups move down
from higher latitude going down towards the equator.
Sunspot
zones:
Most sunspots are confined to maximum latitude of +35°-40° and -35°-40°.Some spot can apppear as as +70° and -70° for brief periods.As the solar cycle develops the sunspot move towards the equator until sunspot minimum they do not disappear altogether,but are at their minimum total number for the
entire cycle.You may have a few day were sunspots are not present on the face of the Sun that is visible to the observer here on the Earth,but a few spots still may be present on the
other hemisphere not visible from our viewpoint.It is also common as the Sun starts to get close to solar minimum to have sunspots close to the equator(the old cycle +/-7°)and spots at higher latitude(the new cycle +/-35° to 40°).This is a good way to indicate the start of a new cycle
Naked-Eye Sunspots :
This is where a Sunspot group can be seen on the disk with help from no optical
device.This kind of sunspot group was seen in China some 2000 years
ago.To see this type of group you need to remove the Sun's glare.To
do this you will need some form of glass filter or a mylar filter.If
a naked eye sunspot group is present you will note a dark mark on
the disk of the Sun,it may even appear as if the Sun has a hole in
it.These kind of groups are seen easily at the centre of the Sun's
disk.If you do this kind of observation you will need patience,especially
at sunspot minimum as large groups of sunspots are very rare so no naked
eye groups will be seen.At sunspot maximum you may observe 4 or 5
groups a month,these group may be seen for their entire journey across
the disk of the Sun.It should also be noted that only the biggest
groups may be naked eye groups of McIntosh type Dkc,Kkc and Fkc are
most likely to be naked eye.
The Connection between the Umbra
and the Penumbra Areas:
Each sunspot starts it's development
as a pore then moves onto an individual spot without a penumbra.The
penumbra increases in significance as the sunspot increases in area.Large
groups show massive penumbra which surrounds many umbra.As
the group begins to break up the penumbra shrinks faster than the umbra.
The
Brightness of the Umbra :
The brightness of the umbra changes
as it is connected to the magnetic fields of the sunspot or sunspot
groups itself.So it will change with the sunspots development.Visual
observations are too inaccurate for two reasons.1.The eye see's large
Sunspot groups darker than smaller groups.2.The amount of scattered
light in small sunspot groups can exceed 50%.So any studies of the
umbra brightness are only of any use if a photoelectric measuring
device is used.This determines the amount of scattered light in the
observation.This kind of device may only be available to a few solar
astronomers so many amateurs will be unable to do any observable records
with regards to umbra brightness.
The Development of Sunspots
and Sunspot Groups:
As seen earlier,all sunspots develop
from pores then they may form Sunspots,seen
earlier.It should be noted,that at any stage of development the Sunspot
and eventually sunspot groups could stop and the sunspot or sunspot
group could disappear.Some large sunspot groups will show rapid changes
in their lifetime,new spots appear,others disappear,some change their
relative position,some of the larger spots may split into two or three
individual spots,the penumbrae will change as well as new penumbrae
appearing and light bridges may develop.Some sunspot groups may show
rapid changes,To be called rapid changes they must happen in a few
hour,or even a few minutes.These kind of changes are mainly concerning
smaller spots developing and disappearing but the penumbra can also
show rapid changes as well.
Measuring Sunspot
activity:
All spots are given classes,this what
the McIntosh Sunspot classification is used for.It has been modified
to remove some problems that occurred in earlier classifications.
McIntosh
Sunspot Group Classification.
Modified Zurich Class.
Spot
cluster type.
A:Single spot or group of spots without penumbrae
and without bipolar structure.
B:Spot group with out penumbrae
in bipolar structure.
C:Bipolar group,one of main spots has penumbra.
D:Bipolar
group,both spots have penumbrae,and at least one spot shows some structure.The
maximum extension of the group is 10° on the Sun.
E:Large bipolar
group,the main spots are surrounded by penumbrae and have a complex
structure.Between the main spots here are numerous small spots.Extension
of spots at least 10°.
F:Very large bipolar or complex spot group,extension
at least 15°.
H:Unipolar spot with penumbra,diameter greater than
2.5°.Penumbra type.
X:No penumbra.
R:Rudimentary penumbrae partially
surrounds the largest spot.This penumbrae is incomplete and is granular
rather than filamentary,brighter than mature penumbra the penumbra
may be forming or dissolving.
S:Small,symmetric.The largest spot
has a mature,dark filamentary penumbra of circular or elliptical shape
with little irregularity to the border.The umbra is either a single
or cluster of umbrae,mimicking the symmetry of the penumbra.The north-south
diameter across the penumbra is less than 2.5°.
A:Small,asymmetric
Penumbra of the large spot is irregular in outline and the multiple
umbrae within it are separated.The north-south diameter is less than
2.5°.
H:Large symmetric,same structure as 'S' north-south diameter
greater than 2.5°.
K:Large asymmetric,same structure as 'A' but
north-south diameter is grater than 2.5°.
Penumbra on the largest spot.
x:No penumbra (class A or B).
r:Rudimentary penumbra partly surrounds largest spot,either forming or decaying.
s:Small,symmetric penumbra,elliptical or circular.There is either a single umbra or compact cluster of umbrae,mimicking the penumbral symmetry.N-S size smaller than 2½°(30,000km).
a:Small,asymmetric penumbra,irregular in outline.N-S size smaller than 2½°(30,000km).
h:Large,symmetric penumbra,N-S size larger than 2½°.
k:Large,asymmetric penumbra,N-S size larger than 2½°.
Sunspot distribution.
X:Undefined
for unipolar groups.
O:Open.Few,if any,spots between the leader
and follower.Interior spots of very small size.
I:Intermediate.Numerous
spots lie between the leader and the follower portions of the group,but
none of them posses a mature penumbra.
C:Compact.The area between
the leading and following ends at the group of spot is populated with
many strong spots,at least one interior spot posses penumbra.In the
extreme case of a compact distribution,the entire spot group is enveloped
in one continuous penumbreal area.
Unipolar and Bipolar
What do these
terms mean?Unipolar refers to a single spot and Bipolar refers to two or more sunspots.
Sunspots groups latitudes:
It should also be noted
that at times of sunspot minimum there are few groups of spots(if
any at all).As the solar cycle progress,the class and number increases,the
closer you get to maximum the closer they get to the equator the groups
will also become more complex.
This
diagram shows how
groups develop north and south as they get closer
to the equator.
leader and follower:
As the names suggest leader and follower is a reference to bipolar groups of sunspots.
A bipolar group will have two main spots one at the front "leader"(at the most westerly end of the group) and at the other end the "follower"(at the most easterly end of the group).
It is also common in this kind of group to have the leader closer to the equator by 11° at sunspot minimum and 3° at sunspot maximum this has come to be known as "Joy's Law".
The term "Joy's Law" is not governed by sunspot minimum or sunspot
maximum but by the spots latitude.
Occasionally,you may get a leading spot with the wrong polarity.When a spot with the wrong polarity is present,it could put the lead spot at the same latitude or higher than the follower in a group. Also large complex groups with mixed or inverted polarities will very often violate Joy's Law.
The Sunspot number:
Most white light
observers will only be able to count the numbers of sunspots and Sunspot groups.This technique was developed by Rudolf Wolf in 1848.It
is an easy and world wide recognised way of measuring Sunspot numbers.It
is now known as the "Wolf Sunspot Relative Numbers",it may also be
known as "The Zurich Number".This is the formula R=k(10g+f)This is to
show how the formula is worked out.On the Sun,the day you observe,you
see 4 Sunspot group with a total 23 this is how you get your relative
Sunspot number 10x4+23 R=63.
Light
Bridges:
Some sunspots have areas that resemble the Photosphere.They look like
narrow tongues projecting into the sunspots.They may also just be
an island in the centre of the spot.Light bridges are broken into
three main types.
"Classic light bridges":
Bright
intrusions into the sunspot with a structure similar to the photosphere.There
is normal granulation,and brightness is similar to that of the faculae
and the outer ring.They can last for a day to several weeks.
"Islands":
These
are situated in the penumbra of the spot with no direct link to the
photosphere,appearing as brighter areas between the the dark penumbra
filaments.In the regions where islands are present the penumbra appear
irregular or ragged,its radial orientation(away from the centre of
the spot)is affected.Islands can last a few hour to several days.
"Streamers"
These
types of light bridges are the most difficult to observe and are found
in most sunspot groups.They often divide into a short lived network
with in the umbra,where they often connect opposite parts of the inner penumbra.Very
high resolution photographs show that they are extensions of the individual
bright penumbra filaments from which granules break off.Again they
last several hours or days.
Light bridges should not be confused with a white light flare(white
light flares last minutes ).Light bridges can change over there life
time.Light bridges show a wide diversity of brightness,but often
appear more radiant than the surrounding Photosphere.This is only
an illusion,however,produced by the sudden contrast between the flowing
strip of the solar surface and the spot's umbra.When observing in
white light the light bridges accompanying sunspots near the limb
appear brighter than the Faculae.Here are the kind of light bridges
an observer can
see.
A picture that shows how light bridges may appear on a sunspot.
Development of a light bridge.
This will tell you in six stages how light bridges develop.
A.No
light bridge is present.
B.Bright penumbra filaments project from the inner penumbra to the
umbra.Very often this happens from both sides of the umbra.
C.Granules start to break off the bright penumbra filaments and travel
to the centre of the umbra.
D.If a streamer is formed then the penumbra begins to connect.
E.The
Sunspot is now divided but remnants of the dark penumbra filament
remain in the light bridge.
F.Now a classic light bridge remains.
Most
light bridges have only two rows of individual granules,but it
is brighter than the streamers.
Stages of light bridge development.
"adapted from Solar Astronomy Handbook by Beck,Hilbrecht,Reinsch and Volker."
Each of the stages could be the last stage.For unknown reasons successful
light bridges appear to recede.Also the interaction between increasing
activity and Sunspot decay does not appear to be a progressive process.
Wilson Effect:
This is an affect seen in sunspots,it
was first noted in 1769 by Dr Alexander Wilson from Glasgow,he noted
an unusual phenomenon,spots that were near the eastern or western limb.As spots move towards
the east or west limb it starts to resemble a cavity or well.
The Wilson effect.
So Dr
Alexander came to the conclusion that sunspots were in fact cavities
with different depths.Dr Alexander Wilson explains the effect by assuming
each sunspot was a conical shape in the solar surface and so giving
the desired effect .
The
wilson effect in perspective.
The models by modern solar physicists resembles a cone.The
Sun has no solid surface,
it is gases with a continuously decreasing density.The umbra is more
transparent than the penumbra and the penumbra is more transparent
than the photosphere,the depths of the spots are 500 km's to 1,000 km's depending
on size.
Wilson effect problems:
Present day equipment has confirmed
the Wilson effect ,but a problem has arisen.The reason for this has
come to light due to the limit of early optical equipment.It was also
not reported by earlier observers that asymmetrical Sunspots do not
show the Wilson effect,if they are very asymmetrical then it may show the
complete opposite.Work done by a few solar observers have
come to the conclusion that the shape of the spot cancel's out this
effect.
Wilson effect on an asymmetrical Sunspot.
.
Faculae:
Introduction:
These
are areas of hot gas just above the surface
of the Sun.It
is about 300° hotter.Faculae are seen around sunspots but
can also appear before sunspots form,or after the sunspots have gone.In fact faculae
appear all over the Sun,but they are best seen near the limb of the Sun
where the limb darken's.Fraculae consist of aligned mottles 5,000 km's to 10,000 km's
wide and 50,000 km's long.They are in turn made up of oval-shaped
course mottles with a diameter of about 5000 km's.The course
mottles are made up of faculae granules about 1000 km's in
size.The average life time of faculae is about 90 days.
Classification:
There does not exist any analogy
with
the classification code for faculae as for that of sunspots.Two practised
methods to be discussed in the
following paragraphs relate to the structure or area of faculae.Classification
according to the structure of of the faculae goes back to a suggestion
made by Gericke.Five types are distinguished and coded with lower
case letters. below
Type a:streaky,net like structure
Type b:large contiguous areas
Type c:subdivided areas
Type d; Point Faculae.
Type e;Cluster of point Faculae.
diagram showing faculae classification.
"adapted from Compendium of Practical Astronomy by Gunter Dietmar Roth."
The area of a faculae region should be at least 80% contiguous to
be counted as type b.Type b includes a maximum of two small separate
faculae areas;type e includes more than two.Just like sunspot classification
codes sometimes causes problems,so too do the faculae classifications
region is not always unambiguous.
Classification according to the area of a faculae region goes to a
10-step scale estimating the {size of area in square degrees of heliographic
coordinates.For this method projection would be more helpful than
direct observations.The scale contains the following 10-steps(the
area in square degrees):
Shows the size classification up to stage 4.
"adapted from Compendium of Practical Astronomy by Gunter Dietmar Roth."
Polar Faculae:
Their is also polar faculae this does not occur in the
sunspot regions.To be called polar faculae it must be seen above(north)
or below(south) 50° in latitude.
Polar faculae are smaller than that of main region faculae
they are 1450 miles in size.They are small points or oval in shape.There
life time can be a few minutes or they can last a few hours.When sunspot
are at minimum activity then polar faculae are at maximum and visa
versa.
As Faculae are small a large telescope is needed,with a small telescope
only the bright Faculae can be seen,so leading to incomplete
results.It takes some practice to see Polar Faculae so at first you
may not find it.
When recording your result you should not add it to your
faculae in the sunspot regions.Other wise this would up set your results
.You should also remember that the Sun at certain seasons sees
more of the northern hemisphere.At other seasons more of the southern
hemisphere can be seen,this must also be allowed
for in your results.
The position measurements of polar faculae can
show distribution of activity with latitude.Observation made over
several
hours on one day will yield data on the lifetime of faculae.So polar
faculae gives you interesting studies during solar minimum.
H-Alpha observations:
Here we will
see what kind of detail amateurs can see in the Chromosphere.In this
section the terms prominence's and filaments will be explained .The
Chromosphere can only be seen using a special filter,it may also be
seen during an eclipse as a thin red ring around the Sun.We will be mainly looking at H-Alpha observations as the filters need to see this detail have moved into the price range of most ameteur solar astronomers.The face of the Sun in H-Alpha shows a lot of detail,that can not be seen in white light.You can see the changes in proninences as well as how prominences move onto the disk to cause filaments and hoe these change as the move across the disk.The picture below shows this over a 12 day period.
From the Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany.
Plages:
Plages comes
from the French term "plage faculaire"It is known that both(faculae and Plages)have
the same form,appearance and they are both linked with sunspot groups.It is also known that plages and faculae do appear in the same places but not on an exact "1-to-1" correspondence in locations.This tells us they are not the same features.Plages are a good indicator whether
an active region is in development or decline.Chromospheric faculae
are visible all over the disk whereas photospheric faculae can only
be seen close to the solar limb.It should also be noted that the boundaries
of Chromosphere faculae group are easily discovered unlike that of
white light faculae.If an observer has a filter set at about 150 Angstroms
bandwidth or in blue light,then an observer have continued to see faculae near
the center of the solar disk.Chromospheric Faculae is now more often
referred to as just "plage".
Waldmeier has called attention to one other
set of characteristics in particular plages.He noted other phenomena
in an active chromosphere disappear after a short time,such as spicule,flares,eruptive
prominence's and filament's.Where as Chromosphere faculae do
not!He stated that a sudden disappearance of plages has never
been observed,but after each rotation the plages become more spread
out and diffuse until they finally do not stand out against the chromospheric
structure.It is also important that Chromosphere faculae are not mistaken
for flares and visa versa.
With regards to recording your observational
data you can use the same methods used to record white light facula.
Prominence's:
What are prominences?
Prominence's are clouds of cool gases suspended
in the Sun's atmosphere.They are made up mostly of Hydrogen.They do vary
in size.Some are up to 600,000 km's long and 10,000 km's wide and
reach heights of 48,000 km's.Some prominence's can last many rotations
of the Sun.It should
be noted that prominence's can be seen during a total eclipse and appear as a red or pink structure seen Protruding into the Corona.
Quiescent:
These
are long lasting prominence's and can last many rotations.Any changes
that this type of prominence has,is slow in happening.One of the most common type of Quiet Region Filaments(QRF)is the hedgerow prominence.It looks like a hedgerow of bushes.This type of prominence tends to show fine detail,hedgerow prominence's are also in
contact with the surface of the Sun at only a few points.
A Hedgerow prominence seen on 01/08/2000.
This type of prominence occurs all over the Sun from low latitude to high ones.Quiescent prominence's are mainly found at particular
latitude belts on the Sun.Some are found on the poleward side north
and south of the sunspot groups in the active region of the
Sun.There they form to "Royal Zones" which move steadily towards the equator
with the spots.The
filaments lie on magnetic inversion lines.Just after sunspot maximum
a second group of prominence's appear at the higher latitude,these
form polar crowns.The prominence's show poleward movement and reach
the poles at the next maximum.It is most likely that the prominence's
of the lower latitude are first groups that have moved poleward to form
the second group.,this
type of prominence shows great detail.QRF appear in many other forms such as arches,fans,curtains,flames,spikes,pillars and many others The most spectacular
movement is when it comes to a end of its life it can rise of the
surface of the Sun at great speeds of up to several miles/km's a
second.This is known as a "Disparition Brusque".This type of eruption will only last one or two hours.Disparition Brusque vary from a fully lifting off from the Sun then drifting away and breaking up as it does so,some surface brightening may be seen,or the Disparition Brusque could just be a simple fading of the prominence.
A Disparition Brusque seen on the 02/08/2000
from 16.30UT-18.15UT.
On some occasions a vanished quiescent may reform near it last locations a few hours or days later.Active Region Filaments(ARF's) when seen on the solar disks are usyally smaller,darker and narrower than QRF's.They can be seen in or close to active regions,and may be winding around or even through sunspot groups.
Active Filaments/Prominences(Eruptive Prominences):
As
the name indicates these type of prominences happen suddenly and show great movement in a short space of time.There will also be massive change within the prominence.Some eruptive prominence's will
be quiescent prominence's at the end of its life or they will be due
to a flare,as this indicates most happen close to active areas (sunspot groups).These type of eruptions are the most violent and will last
a short space of time.
Eruptive prominence's are also broken
into sub groups:
Caps:
Caps are seen above
active regions,as low lying prominence's.They also have surges ejected
from the side of the cap.Caps can last for a few hours or a few days.
Surges:
Surges
shoot out of the Sun,ascending in a straight or curved column with
speeds of 50 and 200 km's/s with heights of up to100,000 km's,then descending
back to the sun usually using the same path,Surges occur in the same
place many times.
Sprays:
Sprays are explosive events which
eject material at speeds of 2,000 km's/s higher than the escape velocity
of 20 km's/s.This event is so energetic that the matter is not contained
but comes out in fragments when ejected.
Loop prominence's:
Loop
prominence's as the name indicates are loops of material which fade
after a few hours.Loop prominence's are also known as Ribbon prominence's.They
can reach heights of 100,000 km's above the surface.
Coronal
Rain:
Coronal Rain is loop shaped,but is only apparent
by bright blobs that fall back to the solar surface.
Two eruptive prominence seen on 29th of June 1995 at 17.20UT till 17.38UT seen using a daystar filter set at 0.7Å using a 1½ E.R.F.
An eruptive prominence seen on 26th of June 1998 at 14.120UT till 17.28UT seen using a daystar filter set at 0.7Å using a 1½ E.R.F.
An eruptive prominence seen on 28th of November 1999 at 11.070UT till 11.40UT seen using a daystar filter set at 0.7Å using a 1½ E.R.F.
Spicule:
This is
a spike like structure seen on the limb
of the Sun,are about 800 km's in diameter and reach heights of 14,500 km's.They last for 5-10 minutes . Most easily seen at the solar poles,but this feature is also visible all around the limb of the Sun in H-Alpha.As well as this,they can be seen as dark features
overlying the Chromospheric network elements when observed in the wings
of H-alpha.They have an acceding rate of 20-30 km's/sec.The only place you do not generally find spicules are in
active regions with bright plage.
Prominence classifications:
For many years scientist
tried to class up prominence in groups,the trouble was that all the
classification schemes used physical parameters . These are not always
obtainable.or need many sets of observation.It was not until 1969(by
Volker)that a system was devised which was easy to use and so you could
make a classification quickly.It is suitable for amateur solar astronomer
to use.It is broken into three groups,each of which is given a letter
Bar-shaped prominence's(S),Arch-shaped prominence's(B) and Area prominence's(F)
for each of these,class size is taken into account and a letter
is given to each size small(A)large(B)unusually large(C)detached(D).
This diagram shows
the prominence
classes devised by Volker in 1969.
"adapted from Solar Astronomy Handbook by Beck,Hilbrecht,Reinsch and Volker."
The chart above is an older way of classing prominences.As prominence's forms vary a lot from day to day basic another scheme was set up(Zirin).This new scheme is useful for categorizing the types of prominences,this scheme is now used by most solar astronomers all over the world.
Present day Prominence class:
Class 1:
Quiescent prominences/filaments:
(long lived,fairly static).
A.QRF: (Quiet Region Filaments)Hedgerow,curtains,arcs,fans to name but a few.
B.Ascending Prominences: (end of the quiescent phase)."Disparition Brusque"(lifting off) eruption.
C.ARF: ( Active Region Filaments)a filament in or close to an active region(netural line filament).
Class 2:
Active prominences/filaments(short lived,moving).
A.Limb flare: (bright blobs,may change it an eruptive prominence).
B.Surge: Spike shaped ejected of material previously not seen(a sudden gas jet).
C.Sprays: A unshaped ejection,will previously have been visible as a pre-flare elevated feature(violent explosion).
D.Flare loops and Coronal rain: (often post flare ejections or other gas).
Filaments:The most out standing disk detail in H-Alpha are the filaments,these look like long dark winding lanes.Known as "dark flocculi" by early solar observers.Quite frequently,a limb prominence can be seen in continuity with
a filament,confirming that it is one of the same formation.Quite
naturally,filaments will change their positions on the Sun from day
to day,due to solar rotation . A filaments change their position on
the Sun the filament will change its shape because of the effects
of the perspective.At the centre of the disc they tend to appear as
long dark lanes but near the limb they appear wide and flattened.It is also possible to follow a filament across the face of the Sun.The three pictures below show you how filaments appear on the Sun's disk.
A set of filements seen on 09/04/00.
A set of filements seen on 16/06/00.
A filament seen on the 05/09/01 at 11.00UT.
Eruptions seen as a filament appear as dark black filaments, they appear to move away from the active area at great speed,as they do this they change shape and structure.The filamentous surge, as it known is associated with flares.The ejection of material can be ejected thousands of miles accross the sun.After the activity phase of the flare,the material usually fall back to the sun.
An ejection seen at 13.25UT-13.45UT on the 12/05/01.
Flares:
Flare are an important area of solar astronomy it is important that any person who is thinking of recording flares does so accurately.
What are flares?:
Flares
are a radiation burst and the flares seen in monochromatic light are
only a secondary result of instability of the coronal region above
the chromosphere.One other byproduct of the flare is light which
are substantially brighter than the area around them.Flares occur
in sunspot groups,the more complex the group the more intense the
flare that may occur in that group of spots.
Optical flare
classification chart:
| Importance. |
Area in
square degress. |
Million square
km. |
| S(Subflare). |
Up to 2°. | less than 300. |
| 1. |
2-5 sq°. | 300-750. |
| 2. |
5-12 sq°. | 750-1850. |
| 3. |
12-25 sq°. | 1850-3650. |
| 4. |
more than 25°. | more than 3650. |
Maximum
Brightness. |
| F-faint. |
| N-normal. |
| B-brilliant. |
Brightness chart.
A flare seen 07/07/2000.
A flare seen 12/07/2000.
This section will look at the different kind of flares
and any other phenomena associated with flares
Plage Flares,or
confined flares:
This kind of flare phenomenon occurs
in a (chromosphere) facula region,or coincides with an existing area
of faculae.
White Light Flare:
This kind of flare
phenomenon is rare.In the flash phase of the flare it is possible
for the brightest parts of the flare to be seen in integrated light.The
brightness must be greater than that of the photosphere.Most white
light flares occur in large complex sunspot groups,the most noted
one was the famous Sunspot group seen during August 1972.A white
light flare duration is about 10 minutes and must be at least 50%
brighter than the photosphere.
Spotless Flares:
This kind of flare is not common.They occur if a large filament that was present in an active region,that has decayed erupts.While old fields decay or a new fields come up from underneath the filament may become unstable and move upward.This produces a brightening over a large area.This are not as intense as major flares,and some brightening occurs as the filament move far away from the plage.
Limb Flares:
Limb flare phenomenon occurs at the limb,these do not differ from normal
flares.The flare itself sits relatively close to the surface as an elevated
bright blob,some of the larger flare may achieve exceptional height but as
display's in the form of two classes as active prominences which are surge's
and the spray's.In addition to certain physical features the following
optical features need to be used to distinguish them from prominence's that
may be present on the limb.Active Prominence's cover a large area of
movement at the limb,flares do not!.Also the timing of their development
differs.Doubts about the precise identity of limb flare can arise only if
they are mistaken for a loop prominence in early development phases.In the
case of sprays,this type of prominence's sometimes interact with limb
flares.
see prominence's.
Flare
Kernels or Hot Cores:
These are very bright points in the
flare ,they have a large spectral range and may develop into white
light flares
Two-Ribbon or Two-Strand Flare:
This
type of flare phenomenon is usually linked to an existing filament,the
filament will fill the line of magnetic flux.In many cases the flare
detaches the filament enabling flare loops connections to occur
from one side of the flare to the other.However,in an active region
with sunspots it is not necessary for a filament to exist to have
a two ribbon flare,and the latter may occur without one.
Homologous Flares:
In active regions
flare phenomenon may happen repeatedly in the same region.In this
kind of flare phenomenon the flares development and structure are
almost the same as the previous flare.
Flare Associated Phenomenon:
These
include spays,surges and loops for these phenomenonsee
prominence's.
Moreton Wave(Flare Blast or Flare Wave):
A shock wave from
large impulsive flares that traveles over the surface at speeds of
around 1000 km/sec. They appear as an irregular diffuse moving arc of
brightening in the chromosphere in the centerline of H-alpha, or as a
faint moving dark arc in the blue wing of H-alpha.
In
addition to the types of flare phenomenon above,there are other
flares that are out of most amateur equipment reach these include
impulsive flares,electron flares,proton flare,X-ray flare and hard
X-ray flare etc,so at the moment there is no need to describe them
Go to home web page.
Return to the top of the page.
