Sunspots and Faculae ?

[orestis]

Hi everyone,

I was going to post this in the obs forum but this is a scientific question so i thought i'll post it here.

From what i understand,
Granules are convection cells on the photosphere and radiate away both light and heat.

Sunspots consist of an Umbra and Penumbra,they are considerably cooler than the photosphere,with the photosphere being 6000k,the penumbra 5600k and the umbra 4000k.

The faculae on the other hand are several hundred degrees hotter than the photosphere.

So heres my question are faculae a feature of sunspots and are there more faculae than sunspots.

I Ask this question because i had a recent discussion with a physicist in which we pondered the effect of the sun on climate change.I pointed out that if there more sunspots then the sun would be cooler Right?But then he goes to say that there are more faculae than sunspots therefore leading to a hotter sun.

Another question also if you don't mind-What is the purpose of sunspots are they like huge granules.How do they form and why do they always disappear and come back again?

I think that climate change is Anthropogenic but i think that the Scientist should be doing more studies on how the sun is affecting our climate.

What do you think?
cheers orestis

[CraigS]

Hi Orestis;

Goodness me .. what a terrific question ..!

Ok, so I'm no solar expert but I believe the current theory on all this goes as per my below comments. (Others are free to correct me, if I've got it wrong. My motivation is purely that I believe these questions are too good to go unanswered - this is my best shot at it):

Originally Posted by orestis

Hi everyone,

I was going to post this in the obs forum but this is a scientific question so i thought i'll post it here.

From what i understand,
Granules are convection cells on the photosphere and radiate away both light and heat.

Granules observed in the photosphere, are presently believed to be the 'tops' of columns of rising plasma within the so called solar 'convective zone'.

Sunspots consist of an Umbra and Penumbra,they are considerably cooler than the photosphere,with the photosphere being 6000k,the penumbra 5600k and the umbra 4000k.

The faculae on the other hand are several hundred degrees hotter than the photosphere.

A 'plage' is a bright region in the chromosphere of the Sun (higher in altitude than the photosphere). The plage regions are bigger, so this tends to be what we mostly observe.

Plage areas map closely to the 'faculae', which occur lower down in the photosphere. It is still not clear that both are caused by the same magnetic structures.

Faculae are bright areas observed in Hα or photospheric lines. They are considered to be magnetized regions constituted by a bundle of thin vertical 'flux tubes' with a magnetic field strength of thousands of gauss and a size of tens to hundreds of kilometers.

The faculae, (which, perhaps drive the plages), are considered to have a strong influence on the radiation 'flux', (or strength), hitting the earth.

So heres my question are faculae a feature of sunspots and are there more faculae than sunspots.

The bright spots (or plages) appear in the chromosphere near sunspots and some may indicate underlying faculae. Other faculae appear all over the sun's surface (ie: not just near the sun-spots).

I Ask this question because i had a recent discussion with a physicist in which we pondered the effect of the sun on climate change.I pointed out that if there more sunspots then the sun would be cooler Right?But then he goes to say that there are more faculae than sunspots therefore leading to a hotter sun.

Makes sense because the faculae appear in many places .. not just near to the sun-spots, hence there are more of them than the cooler sun-spot regions. But remember that the Chromosphere is vastly hotter than the photosphere and I don't think they've quite agreed on why, yet. (There are sound wave influences and complex magnetic interplay reasons as to why this may be so).

Another question also if you don't mind-What is the purpose of sunspots are they like huge granules.How do they form and why do they always disappear and come back again?

Sunspots are caused by huge, persistent magnetic activity which serves to slow down or prevent the convection of hot plasma to the surface. They last (as you'd know for days, weeks etc). Granules are the opposite, really - they are caused by rising plasma. Faculae last for only several minutes and granules may only last for a day or so.
Sunspots are thought to be caused by the interactions of huge rotating currents of plasma within the sun, going at different speeds. As the plasma currents rotate, they cause huge twists or kinks in the magnetic fields and these take lots longer to get straightened out than, perhaps more minor the flux-tubes causing the faculae.

I think that climate change is Anthropogenic but i think that the Scientist should be doing more studies on how the sun is affecting our climate.
What do you think?
cheers orestis

Just remember that the associations between Anthropogenic influences and the Earth's climate are not yet universally agreed. You can believe whatever you like but keep the facts separate from your beliefs.

Hope this helps and is not too confusing. Science is still trying to figure all this out and theories constantly evolve and change over time.

Cheers

[Paddy (Patrick)]

Hi Orestis,

Craig has given you a more comprehensive answer than I could hope to. From my reading, the Sun's energy output is higher in solar maxima due to the increase in faculae & plages. Hence the Maunder minimum was associated with a mini "ice age".

At the risk of opening the festering sore, the link between human activity and climate change is pretty well universally agreed amongst climate scientists. As far as science goes I think it is best to rely on those who specialise in the field. So while I agree that the influence of the Sun on the earth's climate is an extremely important subject, I think its for astronomers to work out the physics of the sun and for climate scientists to work out what that translates to for the earth's climate. And while there's more to learn there, I don't think there is much disagreement that any contribution of variations in the Sun's output to recent global warming is small

[orestis]

Thanks a lot guys,

I understand it a little bit better now as i had no idea what plages were until now thanks for that.

I would think that the corona would be cooler than the photsphere but i have now read up on it and it is infact very hot ranging from 1 million k to 5 million k.Thats hot.

But why ?Why is the corona so hot?

Craig-On your last point about keeping fact away from belief I agree with you but I think you misunderstood me what i meant to say is that I THINK (not believe) that it is anthropogenic but there may be other factors aswell.

Good point Paddy.

regards orestis

[Jarvamundo (Alex)]

Originally Posted by orestis

I would think that the corona would be cooler than the photsphere but i have now read up on it and it is infact very hot ranging from 1 million k to 5 million k.Thats hot.

But why ?Why is the corona so hot?

....aaaand this would be my definition of intuition.

Well done. You've described the "the solar corona problem."
http://imagine.gsfc.nasa.gov/docs/sc...l1/corona.html

Scientists are still bumping their way through Magnetic carpets and these inventions called "magnetic reconnection" events....

Intuition says, if the corona is hottest, then photosphere cooler, and sunspots colder again, the power comes from outside the sun. Convection from a hot core has no place.

I think that climate change is Anthropogenic but i think that the Scientist should be doing more studies on how the sun is affecting our climate.

More great intuition.

I'm skeptical on anthropogenic global warming too, along with some.. solar scientists http://www.youtube.com/watch?v=5FZZxzB9-Qg

As soon as 'denier' was inserted the issue, AGW became a political issue, not scientific.

The Cloud Mystery: http://www.youtube.com/watch?v=f-PX7gLSwX8 (preview) http://www.youtube.com/watch?v=dKoUwttE0BA (Ful)l

[orestis]

Thanks Alex,

The Sun is such an interesting object to study.

Regards orestis

[CraigS]

Originally Posted by Jarvamundo

Intuition says, if the corona is hottest, then photosphere cooler, and sunspots colder again, the power comes from outside the sun. Convection from a hot core has no place.

More great intuition.

A word of caution Orestis ..

Intuition is not a great basis to work out some of the remaining mysteries in the universe. The coronal heating mystery is one of them.

Science was invented to help us to see things as they are.

Intuition makes us see things which aren't necessarily there.

Tread cautiously.

Cheers

[orestis]

Thanks Craig,
To be honest i really didn't know what intuition was until i just grabbed a dictionary and looked it up.

Intuition-Immediate apprehension by the mind without reasoning.

Which is what i definitely don't want to do.But it just seemed logical for it to get cooler as it you go further out from the sun. That's when science comes in and you test your hypotheses by means of observation or experimentation.

cheers
orestis

[CraigS]

Originally Posted by orestis

Thanks Craig,
To be honest i really didn't know what intuition was until i just grabbed a dictionary and looked it up.

Intuition-Immediate apprehension by the mind without reasoning.

Which is what i definitely don't want to do.

cheers
orestis

Onya matey !!

[Jarvamundo (Alex)]

hahah leaving out the

"But it just seemed logical for it to get cooler as it you go further out from the sun. That's when science comes in and you test your hypotheses by means of observation or experimentation."

so good..

i like this kid.

Orestis, the coronal heating problem is a BIG problem, and a great one to keep an eye on. Well spotted.

[bojan]

Originally Posted by Jarvamundo

hahah leaving out the
so good..

i like this kid.

Orestis, the coronal heating problem is a BIG problem, and a great one to keep an eye on. Well spotted.

Alex, instead of you being too elated about corona problem (perhaps because Carl is quiet for some reason) how about return to our un-resolved issue of stability of stellar relaxation oscillators, huh?
I simply can't allow you to get away with this without satisfactory explanation.
After that you can talk about corona and other things.

[Jarvamundo (Alex)]

The corona problem is MASSIVE.... Modern cosmology has the audacity to proclaim to study the first nano-second after the big bang as fact.... yet we dont even have the foggiest why the sun is hottest on it's extremity, and coldest at the deepest we can see... cmon... has anyone else apart from me and this 14yr old got the gonads to say it's totally illogical...

Rest assured i have the feelers out for frequency stability.... Any ideas where i can get some data? Your questions and thoughts are always valuable to me, i do take them on.

[bojan]

Originally Posted by Jarvamundo

The corona problem is MASSIVE.... Modern cosmology has the audacity to proclaim to study the first nano-second after the big bang as fact.... yet we dont even have the foggiest why the sun is hottest on it's extremity, and coldest at the deepest we can see... cmon... has anyone else apart from me and this 14yr old got the gonads to say it's totally illogical...

Rest assured i have the feelers out for frequency stability.... Any ideas where i can get some data? Your questions and thoughts are always valuable to me, i do take them on.

Corona temperature inversion is not illogical at all... If you take all facts into account. If I were you I wouldn't flatter myself too much - many astro-physicists are working on the issue, and they certainly know more than both of you about this.

Acoustic shock waves can produce it. Acceleration of plasma in strong magnetic field of the sunspots also could be the cause.
BTW, the energy density in corona and chromosphere is hugely different (values in corona are MUCH smaller... Yes, the temperature is higher but the corona mass density is minuscule compared to photosphere.. which rules out your claim that energy source is outside of Sun).

Back to the frequency stability: I am RF hardware engineer, not a physicist.
And I know from experience ("experiment" as you EU people would understand it) how hard it is to obtain numbers only around 0.1ppm - almost everything around such an oscillator has to be controlled and stabilised, and, again, the resonator is still MECHANICAL (crystal). So, I simply cant imagine how to get even close to this lousy number (10^-7) with a huge plasma cloud exposed to all sorts of elements that can affect it. No way..

As I mentioned earlier, if it HAS to be an oscillator (for whatever reason.. and I simply can't imagine what that reason might be.. perhaps because neutron stars can't exist?... but they can, unfortunately .... white dwarfs (larger compact objects) are observed directly.. neutron stars (next step in compactness) were detected indirectly (so far) by the effects they have on their companion), then LGM (Little Green Men) contraption is much more plausible explanation (BTW, this was one of the first thoughts that came to mind to discoverers.. I clearly remember the excitement when reading the first reports and speculations about possible nature of those sources)

[CraigS]

I just found a very interesting article on the limitations of Solar measurements to date:

Living with a star

I highly recommend this article for those interested in Solar observations, as it details the technology limitations in the past, and talks about what is only now possible.

For example, it talks about the previous SOHO, STEREO and TRACE observation satellites:

All previous images of the solar corona suffered from three major limitations:
- One is that they did not combine high spatial resolution with observations that covered the full disk of the Sun.
- Second, the instruments could not take lots of images in quick succession (known as "high cadence" operations) because of limitations to the rate that data could be sent back to Earth.
- And finally, because previous instruments could not take images across a range of different wavelengths, and at a rate comparable to coronal evolution, it was impossible to distinguish whether the observed events were due to heating, cooling or density changes.

But now, with the launch of NASA's new Solar Dynamics Observatory (SDO) mission (only launched in February 2010):

For decades there have been arguments about whether flare or filament eruption can cause another distant event. Now, after only a few months of observations, the Atmospheric Imaging Assembly (AIA) movies have clearly established causality on distances of a solar diameter and more.

The 'AIA' was designed to study how the solar corona responds to the magnetic fields, that the Heliospheric and Magnetic Imager, (HMI) observes near the Sun's surface.

The combination of the onboard instruments are also capable of examining the magnetic fields beneath the surface, before any surface eruptions become visible .. pretty neat !

So, the so called "Coronal Heating Problem" mentioned in previous posts on this thread, is not necessarily a 'problem' solely because of a perceived violation of any laws of thermodynamics. The so-called 'problem' is partly contributed by limitations in the satellite technologies, in the collection of necessary, fundamental data.

So, before forming conclusions about some of the mysteries in the Universe, one should look carefully at many aspects surrounding the issue, including the sensing technology limitations.

Cheers

[orestis]

Thanks for all the input guys i have learnt a few things.

cheers orestis