Found: solar cycles on another star

Distant Star’s Sound Waves Reveal Cycle Similar to Sun – but the cycle is fast, less than 1 year

Star known as HD49933 is located 100 light years away from Earth

View a video on the monitoring of the magnetic cycle of a distant star by the CoRoT satellite.

In a bid to unlock long-standing mysteries of the sun, including the impacts on Earth of its 11-year cycle, an international team of scientists has successfully probed a distant star.

By monitoring the star’s sound waves, the team has observed a magnetic cycle analogous to the sun’s solar cycle.

Results of the study, conducted by scientists at the U.S. National Center for Atmospheric Research (NCAR) in Boulder, Colo., and colleagues in France and Spain, are published this week in the journal Science.

The research was funded by the U.S. National Science Foundation (NSF), which is NCAR’s sponsor, the CEA (the French Atomic Energy and Alternative Energies Commission), the French Stellar Physics National Research Plan, and the Spanish National Research Plan.

“This is an interesting study that was possible due to strong international cooperation,” says Steve Nelson, NSF program director for NCAR.

The scientists studied a star known as HD49933, which is located 100 light years away from Earth in the constellation Monoceros, the Unicorn, just east of Orion.

The team examined the star’s acoustic fluctuations, using a technique called “stellar seismology.”

They detected the signature of “starspots,” areas of intense magnetic activity on the surface that are similar to sunspots.

While scientists have previously observed these magnetic cycles in other stars, this was the first time they have discovered such a cycle using stellar seismology.

“Essentially, the star is ringing like a bell,” says NCAR scientist Travis Metcalfe, a co-author of the paper.

“As it moves through its starspot cycle, the tone and volume of the ringing changes in a very specific pattern, moving to higher tones with lower volume at the peak of its magnetic cycle.”

The technique could open the way to observing the magnetic activity of hundreds of stars, which could help evaluate new solar systems for the potential of supporting life.

Studying many stars this way could help scientists better understand how magnetic activity cycles can differ from star to star, as well as the processes behind such cycles.

The work could especially shed light on the magnetic activity processes that go on within the sun, furthering our understanding of its influence on Earth’s climate.

It could also lead to better predictions of the solar cycle and resulting geomagnetic storms that can cause major disruption to power grids and communication networks.

“We’ve discovered a magnetic activity cycle in this star, similar to what we see with the sun,” says co-author and NCAR scientist Savita Mathur. “This technique of listening to the stars will allow us to examine potentially hundreds of stars.”

In addition to NCAR, the team’s scientists are from France’s Center for Nuclear Studies of Saclay (CEA-Saclay), Paris/Meudon Observatory (OPM), the University of Toulouse, and Spain’s Institute of Astrophysics of the Canaries (IAC).

The team hopes to assess the potential for other stars in our galaxy to host planets, including some perhaps capable of sustaining life.

“Understanding the activity of stars harboring planets is necessary because magnetic conditions on the star’s surface could influence the habitable zone where life could develop,” says CEA-Saclay scientist Rafael Garcia, the study’s lead author.

The scientists examined 187 days of data captured by the international Convection Rotation and Planetary Transits (CoRoT) space mission.

Launched on December 27, 2006, CoRoT was developed and is operated by the French National Center for Space Studies (CNES) with contributions of Austria, Belgium, Brazil, Germany, Spain, and the European Space Agency.

CoRoT is equipped with a 27-centimeter (11-inch) diameter telescope and a 4-CCD (charge-coupled device) camera sensitive to tiny variations in the light intensity from stars.

The study authors found that HD49933 is much bigger and hotter than the sun, and its magnetic cycle is much shorter.

Whereas past surveys of stars have found cycles similar to the 11-year cycle of the sun, this star has a cycle of somewhat less than a year.

This is important to scientists because it may enable them to observe an entire cycle more quickly, thereby gleaning more information about magnetic patterns than if they could only observe part of a longer cycle.

The scientists plan to expand their observations by using other stars observed by CoRoT as well as data from NASA’s Kepler mission, launched in March 2009.

Kepler is seeking Earth-sized planets to survey. The mission will provide continuous data over three to five years from hundreds of stars that could potentially be hosting planets.

“If it turns out that a short magnetic cycle is common in stars, then we will potentially observe a large number of full cycles during Kepler’s mission,” says Metcalfe.

“The more stars and complete magnetic cycles we have to observe, the more we can place the sun into context and explore the impacts of magnetic activity on possible planets hosted by these stars.”

The team has spent the past six months exploring the structure and dynamics of HD49933 and classifying its size.

They will next verify their observations using ground-based telescopes to confirm the magnetic activity of the star.

When the star reemerges from behind the sun in September, they hope to measure the full length of the cycle.

The CoRoT mission was designed to collect up to 150 days of continuous data at a time, which was not enough to determine the exact length of the star’s cycle.

-NSF-

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52 thoughts on “Found: solar cycles on another star

  1. It would be interesting to compare stars, which have numerous physical characteristics, i.e., size, color, magnetic energy, and so on, that are similar to our Sun, but have different magnetic cycles from our Sun (as this post reports, our Sun has an 11 year magnetic cycle as opposed to this other star which apparently has a one year cycle), and attempt to explain why these stars have different magnetic cycles.
    In other words, why do similar stars have different magnetic cycles?
    Is it because, while appearing similar via our observation & measurement, there are different internal dynamics and structural differences, or, are there external differences (physical characteristics & dynamics the star is embedded in) which cause the different magnetic cycles?
    This seems to be an interesting line of research because it allows Science to investigate whether its assumptions about helio-physical dynamics are correct or false.
    How much to we really know about the dynamics of our own Sun?

  2. So yet more examples of “we don’t know”. Why don’t we admit, we don’t know, it is OK to do that. I don’t know how to cook risotto (My first and only attempt failed)!

  3. Anthony,
    Thank you for keeping news of these fascinating scientific discoveries coming. They help to keep our wonder alive!
    MikeEE

  4. “Sound waves”? “Acoustic fluctuations”? I’m not questioning the science — I don’t understand it — but I’m not getting the terminology. Sound waves are vibrations that travel through the air, or some other medium. Are they translating magnetic pulses into sound waves? I can see that, but then they’re studying magnetic pulses, not “sound waves.”
    Makes me feel like yelling out in frustration — but in space, nobody can hear you scream. (Unless you’re a star, apparently.)

  5. Patrick Davis says:
    August 27, 2010 at 9:37 am
    “So yet more examples of “we don’t know”. Why don’t we admit, we don’t know, it is OK to do that. I don’t know how to cook risotto (My first and only attempt failed)!”
    Science saying, “we don’t know,” is the first step to gaining new knowledge.
    Science saying, “we know it all,” is the first step to dogma and blocking advances in scientific understanding.

  6. http://in.news.yahoo.com/139/20100826/981/tsc-massive-solar-storm-to-hit-earth-in_1.html
    Speaking of solar cycles, I just noted the story above on Yahoo. The alarm bells went off loudest when I noted the famous words “Most experts agree, although those who put the date of Solar Max in 2012 are getting the most press.” Ah yes, that famous phrase “most experts agree”. On which planet this reality might occur I have no idea, but it is not this planet.
    I love it that they have the balls to announce two years in advance that for sure the sun will blast our planet with a satellite destroying, power line frying, circuit breaking EM blast………give or take a year. Or maybe decade or whenever Solar Cycle 24 really decides to arrive. Until then I won’t lose sleep over something that we humans can do nothing about.

  7. What have these “sound wave” observations told us about our own Sun? I assume that’s been done and used to calibrate stellar observations…

  8. As far as I can figure out, ‘sound waves’ will be the equivalent of acoustic waves (alternate regions of high/low pressure) moving through the coronosphere. Does that make sense?

  9. Starspot cycles have been observed on dozens of other stars to date. This group and other groups have been developing asteroseismology techniques to interpret fluctuations in stellar light curves as interior activity.

  10. James F. Evans:
    “It would be interesting to compare stars, which have numerous physical characteristics, i.e., size, color, magnetic energy, and so on, that are similar to our Sun, but have different magnetic cycles from our Sun (as this post reports, our Sun has an 11 year magnetic cycle as opposed to this other star which apparently has a one year cycle), and attempt to explain why these stars have different magnetic cycles.
    In other words, why do similar stars have different magnetic cycles?
    Is it because, while appearing similar via our observation & measurement, there are different internal dynamics and structural differences, or, are there external differences (physical characteristics & dynamics the star is embedded in) which cause the different magnetic cycles?
    ================================
    Given that a primary theory for the 11 year solar cycle and its variation plus and minus is that it is driven by the gravitational impact of the orbiting planets, it would be interesting to test this theory against another star where planet masses, orbits, etc. are known (if in fact we have that information for another star at this point).

  11. For those expressing confusion, stellar sound waves are transmitted to us through the aether, which is obviously compressible because dentists store it in high-pressure bottles.
    Dr. Science, D- degree in junior high school physics.

  12. George Turner says:
    August 27, 2010 at 12:07 pm
    For those expressing confusion, stellar sound waves are transmitted to us through the aether, which is obviously compressible because dentists store it in high-pressure bottles.
    Dr. Science, D- degree in junior high school physics.

    Now see? All I needed was a reasonable explanation.

  13. Substitute seismic for acoustic in the above story, and then you will understand. They are basically studying what would be called star quakes if stars had solid surfaces, but stars don’t have solid surfaces. They have plasma instead. It behaves kind of like a liquid.
    A solar flare erupts sending out ripples that circle the star, like tossing in a pebble sends out ripples on a pond.
    What they are talking about is measuring the frequency of the ripples.
    They call it the p-mode acoustic field I suppose because they needed to call it something.
    You’ve seen it used before and reported by Anthony when he pointed out sunspots erupting on the opposite side of the sun.
    See helioseismology, star quakes, GONG experiment,
    http://gong.nso.edu/

  14. Our Sun is seated and that star is at the gym, that’s all. This theory is better than consensus. 🙂

  15. Solar cycles on other stars is not a previously undiscovered concept. In 1992, Baliunas found a number of stars with Maunder Minimum like periods of relative inactivity. It is reported in this link:
    http://atoc.colorado.edu/wxlab/atoc7500/Historical%20Overview%20-%20Solar%20Variability%20and%20Climate%20Change.htm
    Here is the relevant passage:
    “Studies of sun-like stars also point to eras of cyclic magnetic activity punctuated by periods, like our Maunder Minimum, of magnetic quiet. [Baliunas, 1992.]”
    This is the 1992 reference:
    Baliunas, S.L. et al. “Long-term variability of solar total irradiance: studies of solar-type stars.” Eos, 73:14 supplement, 245, 1992

  16. View from the Solent says:
    August 27, 2010 at 10:53 am
    As far as I can figure out, ‘sound waves’ will be the equivalent of acoustic waves (alternate regions of high/low pressure) moving through the coronosphere. Does that make sense?

    It does, but why can’t it be explained in the original article? And if what you say is true, why not call it “pressure waves” instead of “sound waves”? Does it not dawn on the writer that talking about “sound waves” in a press release aimed at the general public might cause confusion? Or did it cause confusion in the writer’s mind, but since doing a bit of investigation would have involved work, he or she just left it as it was?

  17. The interesting part of the story is this other star has such a short cycle.
    See, depending on who you ask, we don’t know why the sun has an 11-12 year cycle.
    So if we can figure out what the difference is between this star and our star, that will get us along way toward figuring it out.

  18. re John says:
    August 27, 2010 at 12:36 pm
    And isn’t it a crime that Sallie Baliunas was viciously attacked by the global warmers.
    If she we’re left unmolested think of how much more mature this science would be.
    The desmogs, realclimates, and sciblogs allowed frauds like Frohlich and Lean to set the world back 20 years in the study of solar cycles.

  19. ‘The scientists studied a star known as HD49933, which is located 100 light years away from Earth in the constellation Monoceros, the Unicorn, just east of Orion.’
    That crap is what is so much crap with SETI@Home. If the dudes and lovely dudettes from SETI@Home spent my computer listening to radio waves from the solar system dominated from HD49933, they’d be listening from radio waves comparable to our 19-century analog crap. But then the stupidoids say what if they were more advanced then us back then. Right like having already gone over to digital communication by flashing light in wireless mode and fiber optics for the old or more advanced stellar quantum communication?They’re using analog listening devices for a reason. :-()

  20. The study authors found that HD49933 is much bigger and hotter than the sun, and its magnetic cycle is much shorter.
    This is not a sun-like star at all. And it has been known for a long time that the bigger and hotter and younger the star is, the shorter is its period. If the star is massive enough it won’t even have a stellar cycle. Cool stars have periods longer than the Sun’s. These are generalizations and reality is a bit more complex. Two important characteristics are rotation period and depth of convection zone and these vary from star to star and especially change with age of the star. Stellar activity is important for the formation of planets, but planets do not seem to have any effect on the activity, unless we assume that planetary systems just conspire to produce the observed relationships with size and age. As many more stars will be examined shortly, the statistics will improve.

  21. Mark says:
    August 27, 2010 at 11:15 am
    “Given that a primary theory for the 11 year solar cycle and its variation plus and minus is that it is driven by the gravitational impact of the orbiting planets, it would be interesting to test this theory against another star where planet masses, orbits, etc. are known (if in fact we have that information for another star at this point).”
    No, it isn’t a “primary theory”. Yes, it is a hypothesis — big difference.
    See, “Do the planets affect the sunspot cycle?”
    http://www.astronomycafe.net/qadir/q923.html
    Upon reading the above discussion, it appears that there are some scientists that attribute the 11 year sunspot cycle to the planets, but this is one of many hypothesis about the cause of the sunspot cycle (I would suggest that Dr. Svalgaard has provided the overall scientific communities’ thoughts on the subject — not that the consensus is necessarily right :-)).
    So, I go back to my original comment: “In other words, why do similar stars have different magnetic cycles?
    Is it because, while appearing similar via our observation & measurement, there are different internal dynamics and structural differences, or, are there external differences (physical characteristics & dynamics the star is embedded in) which cause the different magnetic cycles?”
    The key, here, would be to locate stars which have similar physical characteristics, but have a different stellar cycle. Comparing stars with different physical characteristics would be like comparing apples & oranges.

  22. James F. Evans says:
    August 28, 2010 at 6:35 am
    The key, here, would be to locate stars which have similar physical characteristics, but have a different stellar cycle. Comparing stars with different physical characteristics would be like comparing apples & oranges.
    and when we do this, we find that they have similar cycles.

  23. Sunspot activity on stars….volcanic activity on planets…I need some grants to further research the relationships.

  24. James F. Evans says:
    August 28, 2010 at 6:33 pm
    I sure would be interested in any papers that support your statement.
    Why would you ever doubt what I said?
    From http://www.leif.org/EOS/Stellar-cycles-2010.pdf :
    “~60% of Sun-like stars exhibit regular cycles akin to the Sun’s” and
    “The solar twin 18 Sco [they are hard to find] turns out to have cyclic photometric variations comparable to the Sun’s (Hall, Henry, & Lockwood 2007)”. It’s cycle is slightly shorter [7 years], which may be related to its higher Lithium abundance.
    Bear in mind that the paper is basically a pleas for funding, so tends to underscore differences and discrepancies.

  25. Dr. Svalgaard:
    Thank you for providing the paper.
    Because this is a website on climate, I thought it would be good to give this quote from the paper you provided:
    “Recent work has argued that the Sun is near the end of a 95-year phase of high activity, and that either a full blown grand minimum or much weaker cycles are likely in upcoming decades (Abreu et al. 2009).”
    If this statement turns out to be verified by the coming years and observational data, then a cooling trend is quite possible, and, if so, then this whole AGW business will be exposed for the hoax, I, and others, submit it is (any recent warming could be attributable to the “95-year phase of high activity”).
    But getting back to the point of the post:
    From the paper you kindly provided:
    “Extant programs have not found a statistically significant sample of genuine “solar twins…”.
    And to expand on the quote you provided from the paper: “After another 30 years, the data set is larger but the results remain consistent: ~60% of Sun-like stars exhibit regular cycles akin to the Sun’s…”
    To which Dr. Svalgaard commented: “and when we do this, we find that they have similar cycles.”
    No, that is not what this paper stated, at least in terms of length of cycle, i.e., the paper does not stand for the proposition that there have been a number of “solar twins” which have an 11 years solar cycle like the Sun.
    In fact the quote you, youself, provided states that, indeed, 40% of stars like the Sun don’t have solar cycles that are appreciably like the Sun’s cycle, let alone, an 11 year solar cycle.
    I take the statement from the paper, “60% of Sun-like stars exhibit regular cycles akin to the Sun’s”, to mean that there is a cycling, but the duration and intensity is not the same.
    I encourage readers to link & review the paper Dr. Svalgaard kindly provided:
    http://www.leif.org/EOS/Stellar-cycles-2010.pdf
    Yes, many stars do have solar cycles, but not necessarily the same cycle as the Sun, as the paper stated there is a dearth of “solar twins” to compare with our own star, the Sun.
    I suggest this finding still leaves open the question:
    “Is it because, while appearing similar via our observation & measurement, there are different internal dynamics and structural differences, or, are there external differences (physical characteristics & dynamics the star is embedded in) which cause the different magnetic cycles?”
    It’s true that corollation does not prove causation.
    What all this does suggest is that external differences, i.e., physical characteristics & dynamics the star is embedded in, needs to be studied and considered just as much as assumptions about internal dynamics (afterall, nobody has been able to directly observe & measure the internal dynamics of stars, rather, assumptions have been applied, then, physical frameworks have been hypothesized to buttress those assumptions.
    The book is still open and one must keep an open mind to various hypothesis, least a false idea take root and block advance in scientific understanding.

  26. James F. Evans says:
    August 29, 2010 at 7:40 am
    And to expand on the quote you provided from the paper: “After another 30 years, the data set is larger but the results remain consistent: ~60% of Sun-like stars exhibit regular cycles akin to the Sun’s…”
    To which Dr. Svalgaard commented: “and when we do this, we find that they have similar cycles.”

    We find that they have periods between 2.5 and 25 years with a median around 10. This is what is meant by ‘similar’ cycle lengths.
    The ‘solar twin’ issue is clouded by the definition of ‘twin’. We are applying a VERY strict criterion [perhaps too strict] that the star should be VERY much like the Sun. Only one has been found so far and even it is still a little bit different.
    What all this does suggest is that external differences, i.e., physical characteristics & dynamics the star is embedded in, needs to be studied and considered just as much as assumptions about internal dynamics (afterall, nobody has been able to directly observe & measure the internal dynamics of stars, rather, assumptions have been applied, then, physical frameworks have been hypothesized to buttress those assumptions.
    External differences have no bearing on the cycle issue [that is an unverified assumption on your part], and we are observing the internal dynamics of stars. That is what Kepler is all about: astero-seismology.
    least a false idea take root and block advance in scientific understanding.
    False ideas do not take root as they are ruthlessly removed by observations. This applies to scientists’ view. Of course, among the general public, false ideas flourish and are almost impossible to eradicate, viz. EU, plasma U, Astrology, etc [just look at some of the nonsense peddled on this and other blogs]

  27. Dr. Svalgaard:
    And what about the other 40% of stars that don’t have solar cycles, yet are similar in other physical characteristics?
    Dr. Svalgaard wrote: “External differences have no bearing on the cycle issue [that is an unverified assumption on your part], and we are observing the internal dynamics of stars. That is what Kepler is all about: astero-seismology.”
    No, Dr. Svalgaard, “External differences have no bearing on the cycle issue…”, is an assumption on your part.
    On the other hand, I was not assuming anything, rather, I simply stated, “external differences, i.e., physical characteristics…needs to be studied and considered just as much as assumptions about internal dynamics”, suggesting an even-handed approach, which is consistent with keeping an open-mind — the opposite of making assumptions.
    Obviously, it is you and others that have made an assumption because by taking my statement out of context, and inserting your own opinion that it is only necessary to observe ” internal dynamics of stars” — you have spelled out your assumption.
    Dr. Svalgaard wrote: “That is what Kepler is all about: astero-seismology.”
    But astero-seismology is an indirect observation & measurement technique, only apriori assumptions about what these signals mean, gives interpretive value to the data.
    Yes, scientists never make mistakes in Dr. Svalgaard’ book, particularly Dr. Svalgaard.
    Ask the readers of this website if scientists never make mistakes.
    I bet they won’t agree with your rather self-serving statement.

  28. James F. Evans says:
    August 29, 2010 at 10:24 am
    And what about the other 40% of stars that don’t have solar cycles, yet are similar in other physical characteristics?
    It just means that they don’t have strong cycles this moment. Someone observing the Sun during the Maunder minimum may say the same about the Sun back then.
    Obviously, it is you and others that have made an assumption because by taking my statement out of context, and inserting your own opinion that it is only necessary to observe ” internal dynamics of stars” — you have spelled out your assumption.
    We attribute effects to known causes, and don’t assume [as you] that there are unknown causes that need to be investigated.
    But astero-seismology is an indirect observation & measurement technique, only apriori assumptions about what these signals mean, gives interpretive value to the data.
    Seismology is used to great effect to prospect for oil. All measurements are indirect and must be interpreted within available theory to make physical sense.
    Yes, scientists never make mistakes in Dr. Svalgaard’ book
    I said that mistakes are rooted out ruthlessly by observations.

  29. Dr. Svalgaard wrote: “It just means that they don’t have strong cycles this moment. Someone observing the Sun during the Maunder minimum may say the same about the Sun back then.”
    Yes, that could be, but it could be for other reasons which Science doesn’t understand.
    Dr. Svalgaard wrote: “We attribute effects to known causes, and don’t assume [as you] that there are unknown causes that need to be investigated.”
    This is a silly statement as the business of Science is identifying the causes of physical processes. Also, again, you either unintentionally or intentionally misconstrue my statement: “external differences, i.e., physical characteristics…needs to be studied and considered just as much as assumptions about internal dynamics”, which suggests an even-handed approach, and is consistent with keeping an open-mind — the opposite of making assumptions — certainly a reasonable scientific approach to take.
    Please, Dr. Svalgaard, don’t attribute statements to me that I didn’t make…or is that your idea of “ruthlessly” attacking opinions you disagree with?
    Dr. Svalgaard wrote: “Seismology is used to great effect to prospect for oil.”
    Yes, but then, there is physical confirmation that the oil exists — many times over, which confirm the underpinning ideas supporting oil seismology, whereas, there has never been a hole drilled into the Sun or any other star to confirm or falsify the a priori assumptions underpinning astero-seismology interpretation.
    Dr. Svalgaard wrote: “All measurements are indirect and must be interpreted within available theory to make physical sense.”
    Yes, but there are many observations & measurements where the available theory has been confirmed by multiple observation & measurement techniques…to the point that there is a very high reliability the interpretation is correct.
    And, some are as close to reality as Man gets, i.e., the man observes the leaf is green — for general purposes and even most science, that is considered direct evidence.
    Of course, that is why “theory” is not reality. There is always room to challenge theory if the right test is devised which turns out to falsify the theory.
    In fact, if the theory can’t be falsified, as postulated by Popper, then it isn’t really a “theory” at all, at least in a scientific sense.
    Scientific paradigms have been found to be wrong in the past (Man can’t achieve machanical lighter than air flight — see Scientific American), undoubtedly, scientific paradigms will be found to be wrong in the future.

  30. James F. Evans says:
    August 29, 2010 at 1:04 pm
    Yes, that could be, but it could be for other reasons which Science doesn’t understand.
    You only ascribe reasons if there are indications that they might be some. “could be” is not a reasonable approach.
    certainly a reasonable scientific approach to take.
    No, only if there are indications that point in that direction.
    Please, Dr. Svalgaard, don’t attribute statements to me that I didn’t make
    Which statement(s) didn’t you make?
    there has never been a hole drilled into the Sun or any other star to confirm or falsify the a priori assumptions underpinning astero-seismology interpretation.
    What a priori assumptions? Confirmation comes from agreement with other completely independent data, e.g. we can calculate what the sound speed should be inside the Sun from our models of solar structure. Helioseismology allows us to measure the sound speed and the modeled and observed speeds agree extremely well. We can test helioseismology by looking through the Sun and being able to ‘see’ strong spots on the backside of the Sun, having the inference confirmed when the spot rotates on to the disk. The neutrino flux calculated from the solar model [confirmed by helioseismology] agrees well with the observed flux.
    available theory has been confirmed by multiple observation & measurement techniques…to the point that there is a very high reliability the interpretation is correct.
    I just gave you some examples of that.
    In fact, if the theory can’t be falsified, as postulated by Popper, then it isn’t really a “theory” at all, at least in a scientific sense.
    Everything I have mentioned can be falsified, except the observations.
    undoubtedly, scientific paradigms will be found to be wrong in the future.
    But the observations stand and do not become wrong with time.
    The 32 stars [not counting the Sun] in Figure 6 of http://www.leif.org/EOS/Solar-Stellar-Connection.pdf have an average cycle period of 11.68 years vs. the Sun’s 11.11 years. The differences are likely due to internal factors such as composition and [most importantly] rotation period. Figures 7 and 8 show how the amplitude of the cycle decreases with age of the star.
    In the near future, thousands of stars will have been measured, so the statistics should improve vastly.

  31. Dr. Svalgaard:
    Thank you for providing the paper in your last comment.
    As has happened numerous times in prior comment threads on various posts, the paper Dr. Svalgaard provided, upon close examination, does not support the assertions Dr. Svalggard makes in his comments. It always pays to review authority provided by an interlocutor which is claimed to support the assertions of the interlocutor.
    Dr. Svalgaard wrote: “The 32 stars [not counting the Sun] in Figure 6 of [the linked paper] have an average cycle period of 11.68 years vs. the Sun’s 11.11 years. The differences are likely due to internal factors such as composition and [most importantly] rotation period.
    But the caption for Figure 6 states the following:
    “Fig. 6. The magnetic activity period (y-axis; in years) versus age (x-axis; in Gyrs)
    relationship in a subset of our stellar sample for which period measurements exist.
    No statistically significant trend is recovered in this sample.”
    Visual inspection of Figure 6 reveals that the data points are all over the graph. To speak of averages is misleading at best and nonsensical at worst. Perhaps the caption for Figure 6 says it best, “No statistically significant trend is recovered in this sample.”
    But let’s see the discussion in the body of the paper for Figure 6, as it gives additional information about the proposition the authors intended the graph in Figure 6 to stand for:
    “First we explore the variation in the apparent magnetic activity periods (this information exists only for those stars with chromospheric emission measurements) with age in Figure 6. We find that there is no significant observed trend in the magnetic activity period versus age relationship – implying that the magnetic cycle period of a Sun-like star is independent of age.”
    Again, there is no indication from the caption or discussion that Figure 6 stands for the proposition Dr. Svalgaard asserted.
    I invite readers to review the paper and reach their own conclusions about the validity of Dr. Svalgaards assertions:
    http://www.leif.org/EOS/Solar-Stellar-Connection.pdf
    Dr. Svalgaard presented Evans’ comment: “Yes, that could be, but it could be for other reasons which Science doesn’t understand.”
    Dr. Svalgaard responded: “You only ascribe reasons if there are indications that they might be some. ‘could be’ is not a reasonable approach.”
    But…in the paper Dr. Svalgaard kindly provided, himself, on page 4 it states:
    “Of course one can argue that many of the empirical Sun-Climate relationships don’t really mean anything and could have arisen due to factors unaccounted for. The unknown factors here could be many, and possibly important…”
    So, apparently the paper Dr. Svalgaard provided speaks to, “factors unaccounted for”, and “unknown factors”. There is no discussion of how likely these “unknown factors” are, just that there “could [be] unknown factors”.
    When objections are raised to a scientific assertion due to unknown factors (in this instance, external physical dynamics), it is the responsibility of the proponent of the assertion to affirmatively rule out those factors.
    (Interestingly enough, the paper Dr. Svalgaard provided didn’t even identify the factors, while in my discussion, I, at least, give some idea what those factors could be, i.e., external physical dynamics.)
    Dr. Svalgaard presented Evans’ comment: “there has never been a hole drilled into the Sun or any other star to confirm or falsify the a priori assumptions underpinning astero-seismology interpretation.”
    And, Dr. Svalgaard responded: “What a priori assumptions? Confirmation comes from agreement with other completely independent data, e.g. we can calculate what the sound speed should be inside the Sun from our models of solar structure.”
    Any time there is a theoretical “model” invovled, there are a priori assumptions about the model. And, of course, the danger is that data, observations & measurements, will be massaged (interpreted) to fit the theoretical model, rather, than falsify the model (we see this all the time in climate science models supporting AGW).
    Dr. Svalgaard wrote: “We can test helioseismology by looking through the Sun and being able to ‘see’ strong spots on the backside of the Sun, having the inference confirmed when the spot rotates on to the disk.”
    This only means that the sunspots can be detected through the Sun, not what causes the sunspots — “seeing” does not determine causation. Infact, it suggests that not much is going on inside the Sun because if there was alot of physical activity at various depths or shells of various activity, this would tend to “scramble” (deflect) the sound waves, which apparently isn’t the case according to Dr. Svalgaard).
    Dr. Svalgaard presents Evans’ comment: “undoubtedly, scientific paradigms will be found to be wrong in the future.”
    And, Dr. Svalgaard responded: “But the observations stand and do not become wrong with time.”
    Yes, but the observations’ significance and interpretation can, and often do, change with time, or are superceded by higher resolution observations & measurements than has already been previously observed, or more physical parameters are observed & measured: i.e., older in situ satellite probes could only observe & measure magnetic fields, but today’s satellite probes can measure electric fields in addition to magnetic fields and can observe & measure electron & ion configurations and motions.

  32. James F. Evans says:
    August 29, 2010 at 5:05 pm
    Visual inspection of Figure 6 reveals that the data points are all over the graph. To speak of averages is misleading at best and nonsensical at worst. Perhaps the caption for Figure 6 says it best, “No statistically significant trend is recovered in this sample.”
    Well, the point of the paper is that there shouldn’t be any. The variation between 2.5 and 25 years is the natural variation due to difference in rotation rate and composition.
    “Of course one can argue that many of the empirical Sun-Climate relationships don’t really mean anything and could have arisen due to factors unaccounted for. The unknown factors here could be many, and possibly important…”
    It ought to be clear that the authors do not really put much credence in this.
    (in this instance, external physical dynamics), it is the responsibility of the proponent of the assertion to affirmatively rule out those factors.
    What are the ‘external physical dynamics’? Without any definition one cannot begin to assess their role.
    Any time there is a theoretical “model” invovled, there are a priori assumptions about the model.
    You must make a distinction between the model of the sun and the direct observations of its internal structure. The latter are not based on assumptions [except the usual ones – that the laws of Nature are the same, etc]. You seem to assume that there are assumptions, so perhaps you can enumerate the assumptions, or do you just assume there must be some assumptions.
    This only means that the sunspots can be detected through the Sun, not what causes the sunspots — “seeing” does not determine causation.
    it means that helioseismology provides the observation, much – to use your example a man seeing a leaf calls it ‘green’.
    Yes, but the observations’ significance and interpretation can, and often do, change with time, or are superceded by higher resolution observations & measurements than has already been previously observed,
    Adding another decimal does not invalidate the original observations.
    today’s satellite probes can measure electric fields in addition to magnetic fields and can observe & measure electron & ion configurations and motions.
    as you well know, there are no electric fields in the rest frame of the neutral solar wind plasma; what the satellites measure are induced by moving the plasma across a magnetic field, so your example is not really relevant.
    I have given you several links to papers that should educate you and let you see that stellar cycles are normal and that they for solar-like stars cluster around the same value as the solar cycle so that the sun is quite average in that respect. That you can’t read the papers and extract that bit of information is sad, and I should have known [at least I keep trying as is my wont].

  33. James F. Evans says:
    August 29, 2010 at 1:04 pm
    there has never been a hole drilled into the Sun or any other star to confirm or falsify the a priori assumptions underpinning astero-seismology interpretation.
    Here is [with thanks to D. Kurtz for the imagery] is how this works:
    From the basic laws of physics and from the observable boundary conditions at the surface of a star, we can calculate its interior structure with confidence. Stars are noisy places; they are full of sound waves. Those waves cannot get out of the star [sound doesn’t travel in a vacuum. But the sound waves make parts of the surface move up-and-down and back-and-forth. These movements we can directly observe using the Doppler Effect.
    Close your eyes and imagine you are in a concert hall listening to an orchestra tuning up. The 1st violinist plunks the middle-A which oscillates at 440 Hz. All the instruments then tune to that frequency. But, listen: you can hear the violin, the French horn, the cello, the flute, etc. Out of the cacophony you can identify each and every instrument separately, even though they are all playing exactly the same frequency. Why is that? Well, each instrument is shaped to put power into some of its natural harmonics and to damp others. It is the combination of frequencies, amplitudes, and phases of the harmonics that defines the rate of change of pressure with time coming from the instrument – that defines the sound waves the instrument generates.
    A sound wave is a pressure wave that in a gas takes the form of a rarefaction and compression of the gas that propagates at the speed of sound. The information that a change in pressure is coming is transmitted by individual molecular collisions. For the gas in the star the sound speed is v = SQRT((5/3*k*T)/(u*m)). [k=Boltzmann’s constant; u=mean molecular weight; T=temperature, and m is the atomic mass unit]. The speed of sound thus depends through basic physics on the temperature and composition of the gas. Thus if you can measure the speed of sound, you have information about the temperature and chemical composition. Stars are like giant musical instruments, they also have natural overtones, and just as you can hear what instrument makes the music emanating from the orchestra, we can use the observed frequencies, amplitudes, and phases of the sound waves we detect in the stars to ‘see’ their interiors – to see their internal “shapes”.
    Humans are visual creatures, and although our perception of sight and sound are very different experiences, they are physiologically similar and it is indeed possible to ‘see’ with sound. Bats do it all the time with echo-locating that provides the bat with an internal image of the world around it.
    Similarly, helio- and asteroseismology use astronomical observations – photometric and spectroscopic ones – to extract the frequencies, amplitudes, and phases of the sounds at the surface of the star. Then basic physics gives us the sound speed, pressure, density [via the equation of state], and temperature throughout its interior. These are in a very real sense all the equivalent of the electro-chemical signals in our brain that are transmitted from the photons absorbed by the retina. We build up a picture in the 3-D theatre in our minds of what the inside of the star looks like. We see inside the star with sound, like the bat sees its world with sound. What we see matches what we calculated, and this gives us confidence [both of the calculation and of the observation] that it is all as real as stubbing your toe to convince you that a rock is real.

  34. Of course, Dr. Svalgaard is free to offer the last word, as is often his wont in these situations.
    What this set of dueling comments started from was a rather simple suggestion:
    External differences, i.e., physical characteristics…need to be studied and considered just as much as assumptions about internal dynamics.
    This is a call for more information…not less. This is a call for more data — observation & measurement — not less.
    But Dr. Svalgaard essentially calls for less information…move along, nothing to see, here.
    There you have it…a scientist, in essence, wanting to put his head in the sand…the antithesist of the spirit of scientific investigation.
    Dr. Svalgaard is welcome to his opinion. But just as the Sun doesn’t revolve around the Earth…neither does Science revolve around Dr. Svalgaard’s opinion.

  35. James F. Evans says:
    August 30, 2010 at 9:41 am
    External differences, i.e., physical characteristics…need to be studied and considered just as much as assumptions about internal dynamics.
    I think your misconception is what constitutes ‘external differences’. You started out by saying that external differences were something the star was ’embedded in’; one would think of an interstellar medium, location in the galaxy, and such things. Physical characteristics, such as rotation rate, chemical composition, mass, and age are internal differences. These are what determines the cycle length. If you would care to specify which specific external differences you have in mind, then one can assess if they need be taken into account.
    Also, you neglected to tell us which statements you didn’t make.
    Last, internal dynamics are not based on assumptions as I hoped I made clear, but on observations and basic physics.

  36. Leif Svalgaard says:
    August 30, 2010 at 9:56 am
    James F. Evans says:
    August 30, 2010 at 9:41 am
    External differences, i.e., physical characteristics…need to be studied and considered just as much as assumptions about internal dynamics.
    .. You started out by saying that external differences were something the star was ‘embedded in’; one would think of an interstellar medium, location in the galaxy, and such things. Physical characteristics, such as rotation rate, chemical composition, mass, and age are internal differences. These are what determines the cycle length. .
    Yeah, ok how about some super dense cold cloud and watch Ol Sol try to orbit its way up stream through that. Might slow him down and make for some lengthy cycles. Or lets drop him in a hot cloud near a star forming region and watch that cycle sizzle. Maybe we can ram him up against some huge magnetic flux tube or something like that. Or, let’s just pull away from a flux tube into a cooler medium and see how that goes along.
    Steady as he goes.
    Aye, aye Capt.

  37. Carla says:
    August 31, 2010 at 5:51 pm
    Yeah, ok how about some super dense cold cloud and watch Ol Sol try to orbit its way up stream through that. Might slow him down and make for some lengthy cycles
    None of this can make its way upstream. You are trying to say that the pollution in the Gulf would determine the source of the Mississippi.

  38. Leif Svalgaard says:
    August 31, 2010 at 7:13 pm
    Carla says:
    August 31, 2010 at 5:51 pm
    Yeah, ok how about some super dense cold cloud and watch Ol Sol try to orbit its way up stream through that. Might slow him down and make for some lengthy cycles
    ~
    None of this can make its way upstream. You are trying to say that the pollution in the Gulf would determine the source of the Mississippi.
    ~
    lol
    No, I didn’t.
    If the Gulf surrounded the Mississipp, like the interstellar medium COMPLETELY surrounds the heliosphere, you might have a comparison. And the Mississipp, is not embedded in the Gulf the way that the heliosphere is embedded in the interstellar medium. So no comparison.
    ok
    ok
    So, if my cold cloud is moving at 30km/sec and the solar system is moving upwind at 26km/sec into a slightly more dense cloud..
    Group W reminds that we are still having some problems seeing in the forward direction due to all that ionization and particle acceleration at the nose of the heliosphere. We are seeing the boundary fairly well, but just beyond is still hmm ..

  39. Carla says:
    September 1, 2010 at 5:39 am
    So, if my cold cloud is moving at 30km/sec and the solar system is moving upwind at 26km/sec into a slightly more dense cloud..
    Doesn’t make any difference. The outflowing solar wind keeps all that stuff at bay.

  40. Thank you Dr. S. but I’m looking for interstellar cloudletts and flux tubes. Group W’s tinking if we just past a magnetic filamentary on the way over to the overlapping region of two cloudletts, it might be putting a little drag on this satellite we call Ol Sol. The boundary of two magnetic shells where they abutt or a magnetic filamentary region caused by two colliding interstellar cloudletts.
    Bursty quick solar cycles followed by slow low solar cycles. The distrubution of all this messy stuff.
    It’s messy out there.
    Sun’s protective ‘bubble’ is shrinking
    The protective bubble around the sun that helps to shield the Earth from harmful interstellar radiation is shrinking and getting weaker, Nasa scientists have warned.
    By Richard Gray, Science Correspondent
    Published: 1:30PM BST 18 Oct 2008
    New data has revealed that the heliosphere, the protective shield of energy that surrounds our solar system, has weakened by 25 per cent over the past decade and is now at it lowest level since the space race began 50 years ago.
    Scientists are baffled at what could be causing the barrier to shrink in this way and are to launch mission to study the heliosphere.
    ..If the heliosphere continues to weaken, scientists fear that the amount of cosmic radiation reaching the inner parts of our solar system, including Earth, will increase.
    This could result in growing levels of disruption to electrical equipment, damage satellites and potentially even harm life on Earth
    http://www.telegraph.co.uk/news/worldnews/northamerica/usa/3222476/Suns-protective-bubble-is-shrinking.html
    They do suggest the shrinking may just be due to ah variations solar wind speed.

  41. Carla says:
    September 1, 2010 at 2:45 pm
    They do suggest the shrinking may just be due to ah variations solar wind speed.
    And they are quite right about this [just a few days ago the solar wind speed was 700 km/sec]. We are thousands of years away from any known change in the interstellar medium. And none of the clouds out there are really thick, so we are safe for a long time.

  42. Leif Svalgaard says:
    September 1, 2010 at 2:52 pm
    Carla says:
    September 1, 2010 at 2:45 pm
    They do suggest the shrinking may just be due to ah variations solar wind speed.
    And they are quite right about this [just a few days ago the solar wind speed was 700 km/sec]. We are thousands of years away from any known change in the interstellar medium. And none of the clouds out there are really thick, so we are safe for a long time.
    ~
    Well even if the most recent solar wind speed was 700 km/sec., the heliosphere is still travelling at 26 km/sec. So.. if the increase the up wind interstellar wind speed from the presumed 26 km/sec to let’s say 32.5 km/sec and slightly decrease the temp and slightly increase the density, you’re saying .. like no low level desrcreening is occurring. Low level
    How do we know when and how often the interstellar wind changes and becomes bursty, wouldn’t a boundary region exibit more winds, just by virtue of the interaction?

  43. Carla says:
    September 1, 2010 at 3:23 pm
    Well even if the most recent solar wind speed was 700 km/sec., the heliosphere is still travelling at 26 km/sec. So.. if the increase the up wind interstellar wind speed from the presumed 26 km/sec to let’s say 32.5 km/sec
    Imagine you are in a rowboat on a river flowing out of a lake at 20 mph. You are far downstream rowing upstream at 2 mph and now increase our speed to 3 mph, you still won’t get to the lake.
    How do we know when and how often the interstellar wind changes and becomes bursty, wouldn’t a boundary region exibit more winds, just by virtue of the interaction?
    We don’t know very much, but quite a lot can be gleaned from absorption of starlight in different direction, also we can map the clouds with radio waves. Here is more: http://www.lpi.usra.edu/books/CometsII/7015.pdf

  44. Carla says:
    September 1, 2010 at 3:23 pm
    wouldn’t a boundary region exibit more winds, just by virtue of the interaction?
    After two years of IBEX data we are beginning to get a better understanding of the the our Heliosphere. The picture that emerges is one of the interstellar medium flowing AROUND a Heliospheric bubble rather that the Heliosphere looking like a ‘comet’ with a blunt nose and a long tail. http://www.physorg.com/news174908954.html
    Interestingly enough this picture was one of the two possible configurations considered by Gene Parker almost 50 years ago.

  45. Leif Svalgaard says:
    September 1, 2010 at 3:36 pm
    How do we know when and how often the interstellar wind changes and becomes bursty, wouldn’t a boundary region exibit more winds, just by virtue of the interaction?
    We don’t know very much, but quite a lot can be gleaned from absorption of starlight in different direction, also we can map the clouds with radio waves. Here is more: http://www.lpi.usra.edu/books/CometsII/7015.pdf
    ~
    Thanks for the link Dr. S.

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