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Post by justsomeguy on Mar 5, 2012 0:35:19 GMT
You are likely correct, but there was no L and P effect in 14 thus we are in new territory, is that correct? If [as I believe] the Maunder Minimum was due to an extreme L&P effect, we have been there before... Yes we have been here before, but not in cycle 14. |
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Post by lsvalgaard on Mar 5, 2012 2:25:20 GMT
Dr. Svalgaard, Is anyone trying to explain the cause of the L&P effect? Or would that be putting the cart before the horse? Is the effect due to a less active sun, and then makes the sun appear even less active than it already is by making the sunspots less visable? Thanks It is not just due to a less active Sun, as there have been low periods without L&P, but we don't really know, |
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jebbo
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Post by jebbo on Mar 5, 2012 13:52:21 GMT
How much do you think we can learn about the sun by comparison with other stars, especially as we now have a huge collection of high-quality light curves thanks to the Kepler mission?
I suspect it would be impossible to correlate the sun's activity with other stars in any predictive sense as we have a long, continuous set of observations of the sun, versus thousands of 18 month (public) curves for other stars . . . but I'd be interested to know what such comparisons might tell us.
--- Tony Jebson
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Post by lsvalgaard on Mar 5, 2012 16:31:48 GMT
How much do you think we can learn about the sun by comparison with other stars, especially as we now have a huge collection of high-quality light curves thanks to the Kepler mission? I suspect it would be impossible to correlate the sun's activity with other stars in any predictive sense as we have a long, continuous set of observations of the sun, versus thousands of 18 month (public) curves for other stars . . . but I'd be interested to know what such comparisons might tell us. --- Tony Jebson I'll be interested too. I expect we'll learn a lot, but also by patient ground-based observations which already now span decades. One of the important issues is the frequency of 'Maunder Minima', periods of low activity. Another one is the influence or not of close-in large planets on stellar activity. None has been found so far. |
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Post by chickenlittle on Mar 5, 2012 18:38:52 GMT
Dr. Svalgaard,
What's the primary factor driving the sun through it's cycles, reversals? Like sunspots appear to be more of an effect than a cause. And what's the data that we can follow that is closest to that primary causal factor?
Thanks
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Post by justsomeguy on Mar 5, 2012 20:30:05 GMT
Well, here I go with another dumb question, but I cannot find the answer:
Do sunspot sizes normally change, on average, across the cycle? Namely are they larger or smaller, statistically, at any point?
Also, are we still smaller than normal this cycle?
Thanks, sorry for the dumb questions but greatly appreciate the answers.
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Post by lsvalgaard on Mar 6, 2012 0:00:18 GMT
Well, here I go with another dumb question, but I cannot find the answer: Do sunspot sizes normally change, on average, across the cycle? Namely are they larger or smaller, statistically, at any point? Also, are we still smaller than normal this cycle? Thanks, sorry for the dumb questions but greatly appreciate the answers. There is no clear cycle dependence, and yes, we are still running too small. |
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jebbo
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Post by jebbo on Mar 6, 2012 9:29:04 GMT
I'll be interested too. I expect we'll learn a lot, but also by patient ground-based observations which already now span decades. One of the important issues is the frequency of 'Maunder Minima', periods of low activity. Another one is the influence or not of close-in large planets on stellar activity. None has been found so far. Thanks! On the influence of close-in large planets, I've looked at the light curves of a number of Kepler (and Planet Hunter) candidates and I've seen no correlation with activity - at least none is visible in the phased curves I've seen (which is where I'd expect any correlation to be visible), even for extremely short period planets. Obviously this is a subjective judgement, as I've by no means looked at all of them, or even particularly hunted for such a correlation but my bet is there isn't any . . . And when a phased curve *does* show modulation that correlates with the transits, it is a good indicator you're looking at an eclipsing binary. --- Tony Jebson |
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timb
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Post by timb on Mar 7, 2012 7:16:06 GMT
I'll be interested too. I expect we'll learn a lot, but also by patient ground-based observations which already now span decades. One of the important issues is the frequency of 'Maunder Minima', periods of low activity. Another one is the influence or not of close-in large planets on stellar activity. None has been found so far. Thanks! On the influence of close-in large planets, I've looked at the light curves of a number of Kepler (and Planet Hunter) candidates and I've seen no correlation with activity - at least none is visible in the phased curves I've seen (which is where I'd expect any correlation to be visible), even for extremely short period planets. Obviously this is a subjective judgement, as I've by no means looked at all of them, or even particularly hunted for such a correlation but my bet is there isn't any . . . And when a phased curve *does* show modulation that correlates with the transits, it is a good indicator you're looking at an eclipsing binary. --- Tony Jebson Correlation and causation can be really tricky. Just an off the cuff example that may or may not be related...if for example the "frost line" (where gas giants can form) and solar size,rotation, temperature are related, the period of subspots may correlate to objects at the frost line but they may not be causitive. It's a tricky thing to look at two different observations and assign one as the cause the cause and the other as the effect. They could be both, either or neither. |
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Post by lsvalgaard on Mar 7, 2012 16:16:47 GMT
Thanks! On the influence of close-in large planets, I've looked at the light curves of a number of Kepler (and Planet Hunter) candidates and I've seen no correlation with activity - at least none is visible in the phased curves I've seen (which is where I'd expect any correlation to be visible), even for extremely short period planets. Obviously this is a subjective judgement, as I've by no means looked at all of them, or even particularly hunted for such a correlation but my bet is there isn't any . . . And when a phased curve *does* show modulation that correlates with the transits, it is a good indicator you're looking at an eclipsing binary. --- Tony Jebson Correlation and causation can be really tricky. Just an off the cuff example that may or may not be related...if for example the "frost line" (where gas giants can form) and solar size,rotation, temperature are related, the period of subspots may correlate to objects at the frost line but they may not be causitive. It's a tricky thing to look at two different observations and assign one as the cause the cause and the other as the effect. They could be both, either or neither. planets change their orbits in the early stages of formation of a system, so can 'migrate' out of the 'frost zone'. We have, in fact found hot 'mega-Jupiters' very close to their stars. |
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jebbo
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Post by jebbo on Mar 9, 2012 8:57:03 GMT
planets change their orbits in the early stages of formation of a system, so can 'migrate' out of the 'frost zone'. We have, in fact found hot 'mega-Jupiters' very close to their stars. Indeed. For example, HAT-P-7b (aka KOI 2, KID 10666592) is 1.78 times the mass of Jupiter in a 2.2 day orbit! You can view its light curve here: www.planethunters.org/sources/SPH10814001and the phased curve here: i1160.photobucket.com/albums/q490/Tony_Jebson/hatp7b_phased.jpgThis one is big enough you can see a faint secondary eclipse. --- Tony Jebson |
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Post by kalohux on Mar 9, 2012 12:20:39 GMT
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Post by lsvalgaard on Mar 9, 2012 13:59:55 GMT
Because ACE's plasma instrument is broken |
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Post by kalohux on Mar 9, 2012 17:06:42 GMT
Because ACE's plasma instrument is broken Thank you for your answer but how can ACE be up and running again if it is broken? This is probably a stupid question but anyhows? |
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Post by lsvalgaard on Mar 10, 2012 2:29:38 GMT
Because ACE's plasma instrument is broken Thank you for your answer but how can ACE be up and running again if it is broken? This is probably a stupid question but anyhows? The instrument shows wrong [very low values] when solar wind speed goes above a certainly value. Once the speed drops again, the readings are OK. |
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