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Fraser
2004-Jul-29, 04:31 PM
SUMMARY: Scientists from Lockheed Martin and the University of Sheffield believe they've solved the mystery of supersonic jets that dart across the low atmosphere of the Sun. The team used computer modeling and high-resolution images taken with the Swedish 1-metre Solar Telescope to understand how these jets - called "spicules" - are formed. They noticed that the spicules formed in certain spots quite regularly, usually every five minutes or so. This matched sound waves on the Sun's surface that had the same five minute period. The sound waves are usually dampened before they reach the Sun's atmosphere, but wherever they aren't dampened, spicules are formed, propelling matter upward.

What do you think about this story? Post your comments below.

antoniseb
2004-Jul-29, 05:24 PM
One thing that the lengthy Iron Sun discussion [in Alternative theories] showed is that we are still learning some things about the details of the operation of our sun. This is a cool one. There was a recent New Scientist article about this that I linked to up in the Other Stories thread.

om@umr.edu
2004-Jul-29, 06:12 PM
The upward movement of material in the Sun and its departure in the solar wind is likely related to several other puzzling observations, including:

i) The "strange abundance pattern" of s-products at the solar surface [discussed at last week's symposium in Vancouver on "Nuclei in the Cosmos"], and

ii) The high abundance of Iron and Nickel observed at the surfaces of supposedly sun-like stars displaying minimal activity [See the UC-Berkeley news report on the recently completed survey of nearby sun-like stars that mimic the Sun's "Maunder minimum"]

http://www.berkeley.edu/news/media/release...1_maunder.shtml (http://www.berkeley.edu/news/media/releases/2004/06/01_maunder.shtml)

With kind regards,

Oliver Manuel
http://www.umr.edu/~om

Duane
2004-Jul-29, 07:26 PM
Hi Oliver, welcome back :) I hope your trip was worthwhile.

Now, Dr Oliver, in reading this and other comments you have made regarding the Mander Minimum and Jason Wright's paper, it appears to me that you may be misunderstanding the results of the study completed by Wright et al.

I would again point out to you that Wright's full paper is available in the Iron Sun discussion, here (http://www.universetoday.com/forum/index.php?showtopic=2544&st=375).

Wright suggests that the high abundance of Fe and Ni at the surfaces of these stars suggests that they are older stars that have completed their time in the main sequence and are moving into their red-giant stage.

Gosh darn it Oliver, read the actual paper! Please!

Wright concludes that any studies of Maunder Minimums conducted on these older stars are of no use, as these are not sunlike stars, but rather are old stars that have depleted their hydrogen and are moving into their red giant stage.

Note further that the "high abundances" are relative to the Sun. As these appear to be older stars, the abundance of heavier metals is expected to be higher on their surfaces. This is not a puzzle Oliver!

antoniseb
2004-Jul-29, 07:28 PM
Originally posted by om@umr.edu@Jul 29 2004, 06:12 PM
The "strange abundance pattern" of s-products at the solar surface [discussed at last week's symposium in Vancouver on "Nuclei in the Cosmos"]
That looked like a great conference to attend. Schedule (http://www.triumf.ca/nic8/schedule2.html) Which sessions did you sit in on? BTW, which session talked about this "strange abundance pattern" of s-products at the solar surface? [or was this just dinner table talk you had with some presenters?]

Concerning your post here, are you saying that the "strange abundance pattern" is likely the cause or result of the spicules?

StarLab
2004-Jul-31, 06:01 AM
Either way, ignoring the Iron-Sun implications Oliver's arguing that this finding might have, it looks basic, yet unique enough to from now on appear in all the fact books about dear 'ol Sol - assuming that the rest of the scientific community are ready to accept these findings as fact.

om@umr.edu
2004-Jul-31, 11:40 AM
Originally posted by Duane@Jul 29 2004, 07:26 PM
. . . , it appears to me that you may be misunderstanding the results of the study completed by Wright et al.

Wright suggests that the high abundance of Fe and Ni at the surfaces of these stars suggests that they are older stars that have completed their time in the main sequence and are moving into their red-giant stage.


Duane,

I read Wright's paper.

There is a difference between results and suggestions.

Observation: A survey of supposedly sun-like stars displaying minimal magnetic activity observed high abundance of Iron and Nickel at their surfaces.

Wright's Interpretation: These are all old stars.

In fact, in the news report Professor Marcy said, "What astronomers have assumed is that sun-like stars going through a stellar funk are actually very, very old stars whose magnetic fields have turned off forever. They are not in a temporary maunder Minimum, but a permanent one. They're dead."

A Less Sweeping Interpretation: "Deep-seated, solar magnetic fields accelerate H+ ions upward, maintaining mass separation at the solar surface".

["Superfluidity in the Solar Interior: Implications for Solar Eruptions and Climate", J. Fusion Energy 21 (2003) 193-198.]

http://www.umr.edu/~om/abstracts2003/jfe-s...perfluidity.pdf (http://www.umr.edu/~om/abstracts2003/jfe-superfluidity.pdf)
http://www.umr.edu/~om/abstracts2003/jfe-s...uperfluidity.ps (http://www.umr.edu/~om/abstracts2003/jfe-superfluidity.ps)

If the alternative interpretation is valid, then

i) H+ ions are not accelerated upward in sun-like stars without magnetic activity. Mass separation is not maintained in such stars and their surfaces become rich in metals like Iron and Nickel.

ii) H+ ions are accelerated upward in sun-like stars with high magnetic activity. Mass separation is increased. Their surfaces become rich in light elements, like Hydrogen and Helium.

With kind regards,

Oliver
http://www.umr.edu/~om

om@umr.edu
2004-Jul-31, 01:28 PM
Originally posted by antoniseb@Jul 29 2004, 07:28 PM
. . . , are you saying that the "strange abundance pattern" is likely the cause or result of the spicules?
Neither. I am suggesting that the upward movement of H+ ions in the Sun, and the annual departure of 3 x 10^43 H+ ions in the solar wind, likely cause both the spicules and the strange abundance pattern of elements at the solar surface and in the solar wind.

My comments refer not so much to the summary, as to the comment in the full story, "These findings may well lead to a better understanding of how matter is propelled upward into the solar corona to form the solar wind, a stream of particles continuously emitted by the Sun that sweeps past Earth’s orbit."

With kind regards,

Oliver
http://www.umr.edu/~om

antoniseb
2004-Jul-31, 05:12 PM
Tiny posted this question in a parallel thread in the Other Stories section:

I think I remeber in between October and November 2003, an huge flare so called the CME hit Earth and now it's about time to overtake Voyager 1, but does the Solar spicules has anything to do with the CME anyway ?

The paper in question discussed spicules, and did not mention CMEs. While it seems likely that both are connected to magnetic fields in the sun, we can't say that we fully understand the mechanisms for either.

Jason Wright
2004-Aug-01, 01:21 AM
Duane wrote:


Wright suggests that the high abundance of Fe and Ni at the surfaces of these stars suggests that they are older stars that have completed their time in the main sequence and are moving into their red-giant stage.


Hi, all. I'm glad to see that my paper is stirring up discussion! Two points, though, just to clarify things:

1) I have 2 papers out. One is a catalog of activity measurements. Very boring. The second, entitled "Do We Know of Any Maunder Minimum Stars?" is available on astro-ph (http://lanl.arxiv.org/abs/astro-ph/0406338) and is (I hope) more readable.

2) Stars which are metal rich (by which we mean they have many times more iron in their atmospheres than the sun does -- a part in 10,000 instead of a part in 100,000) have always been metal rich. Most don't get that way from nuclear fusion in their cores because that material generally doesn't get to the surface, so high metal abundance doesn't really trace age in a useful way. The reason metal-rich stars and subgiants can get confused is that they have similar brightnesses and colors. When I wrote the second paper, I couldn't tell the difference, so I had to allow for both possibilities.

Now, however, I can tell the difference. Although it might look like metal-rich stars are more inactive, they really aren't. A couple of effects conspired to make it look that way, but now that I have measurements of the metal abundance in these stars, it is clear that it is age, not metallicity, which keeps their activity levels low. I'm working on a follow-up paper to this effect now.

StarLab
2004-Aug-01, 03:41 AM
Which means that the IRON SUN theory is a bit low, doesn't it, your findings?
It has always been about a star's age, not about its makeup and composition.

om@umr.edu
2004-Aug-01, 02:24 PM
Welcome, Jason.

There is no need to jump to conclusions, Star Lab. Future observations may be able to decide between the two interpretations, if the differences are clear.

Does Dr. Wright agree that magnetic activity accelerates H+ ions upward "to form the solar wind, a stream of particles continuously emitted by the Sun that sweeps past Earth’s orbit"?

Does Dr. Wright agree that this upward flow of H+ ions might produce the mass fractionation that enriches light mass (L) atoms in the solar wind relative to heavier (H) ones by a factor ( f ), where

( f ) = ( H/L )^4.56

http://web.umr.edu/~om/images/Excess_light_isotopes_in_SW.jpg

How many stars were included in your survey, Jason?

How long will it be before the magnetic activity turns back on, if these stars behave like the Sun did in 1645-1714, when there was very little sunspot activity over a 70-year?

On other words, how long will it be before we can confidently conclude that, "They are not in a temporary maunder Minimum, but a permanent one. They're dead"?

To speed up a decision, is there any way you could measure a few key isotope ratios at the surface of one of the "dead stars" in your survey?

With kind regards,

Oliver
http://www.umr.edu/~om

StarLab
2004-Aug-01, 06:24 PM
Wait a minute here, I'm just curious:

Does Dr. Wright agree that magnetic activity accelerates H+ ions upward "to form the solar wind, a stream of particles continuously emitted by the Sun that sweeps past Earth’s orbit"?
Is this implying that positively charged particles obey an electromagnetic solar flux within the sun? I'm under the impression that any body with mass in the Solar System can possess heavier elements. Where there's more mass, there's a bigger planet usually, and a greater gravitational field, hence heavier elements within the center of the celestial object. Certainly, in all scenarios and cases, the lighter elemetns always go to the top. Right direction, Oliver, but wrong reasoning.