cacb
Level 3 Rank
Posts: 209
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Post by cacb on Jan 3, 2010 23:24:33 GMT
I can understand that one cannot measure the same quantity as LP. On the other hand, the supposition of disappearing sunspots on MDI continuum depends on temperature differences. I find it hard to believe that from all those lovely SOHO plots one cannot get a measure of temperature versus time, using the the areas or the contrast in number of pixels, or ... . One can, but the selection effect has already happened. We only see the ones that are cold enough to be seen... Perhaps if one used the "raw" (flat field calibrated) continuum images (16 bit FITS format) and measured the ratios between the pixel values of the darkest umbra and pixel values of the surface away from the spots, one could directly measure the contrast, i.e. as the top curve in As it has been discussed before, the daily posted continuum images are 8bit stretched colorizations and would not be useful for such contrast measurements. But I think the FITS files may contain the relevant information.
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cacb
Level 3 Rank
Posts: 209
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Post by cacb on Oct 1, 2009 21:19:56 GMT
From Livingston [30 seconds ago]: "The obs are in the bag. Bill" For 1027 [1026 he didn't get], the mean of 12 spots over 4 days was: 1917 Gauss for field strength 0.850 for contrast Needless to say [!] the results fall just where they should be: Thanks for reporting this Leif, quite exciting material! Thanks also to Livingston for providing his measurements. So how far are we away from confirming L&P (2005)?
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cacb
Level 3 Rank
Posts: 209
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Post by cacb on Sept 27, 2009 19:29:13 GMT
Did Bill Livingston get a reading on 1027 yesterday? Takes a couple of days to process the data... That sounds like "yes". It will be interesting...
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cacb
Level 3 Rank
Posts: 209
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Post by cacb on May 9, 2009 13:24:14 GMT
OT, Bob, Are you game for a visit by me [and Vera] Sunday. There should be some spots even. And/or even later a dark sky. Has the snow melted :-) Good place to stay for the night? Are you predicting spots on Sunday? Go for CCD ;D
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cacb
Level 3 Rank
Posts: 209
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Post by cacb on Nov 27, 2008 21:49:05 GMT
Place an accelerometer on it and tell us what it reads (other than a constant value) ;D Or place the accelerometer on a spaceship on an interplanetary journey (no rocket firings allowed after an initial boost). It will be subject to varying gravity from the Sun, Jupiter and other planets, but will always be in free fall. Maybe it is more correct to say that inertial effects are perfectly balanced by gravity. Gravity. It would be applied even if we didn't agree Who said they have no mass?
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cacb
Level 3 Rank
Posts: 209
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Post by cacb on Nov 27, 2008 14:46:39 GMT
The subject of chaotically varying epitrochoid orbit of the Sun around the barycenter of the solar system was discussed at great length on the 'old board'. One theory (espoused by Fairbridge and others) is that as the barycenter of the solar system moves with the varied positions of the planets and the Sun itself orbits (or is in free fall to) the solar system barycenter. Thus the Sun's orbital and perhaps rotational velocity is altered as it chases the moving solar system barycenter which can be within the Sun or up to 2 solar diameters outside the Sun and move prograde or retrograde. (There is more but that will do for now). The counter argument was that this was not true - barycenters were an unreal construct, therefore the Sun did not have varying orbital or rotational velocity and in any case the planets have negligible effects on the Sun - perhaps a 'tidal pull' of a few millimetres. There is no real debate whether the Sun orbits the solar system barycenter, it does so according to basic laws of gravity. The value you mention is slightly incorrect, the Sun can wander up tp ~2.2 solar radii from the solar system barycenter, not 2 solar diameters. The barycenter is there and so is the varing orbital velocity. This velocity is, however, always quite small (~walking pace) . The Sun is in free fall, so it does not feel inertia forces. You are confusing this with tidal effects, which is something else. The tidal effects are also vanishingly small. The wobble of other stars as well as ours is well known, nothing new. As mentioned there is no controversy over whether the sun orbits the barycenter. The debate has been focused on whether the Sun's orbital movements are related to solar activity. It is difficult to find a physical model explaining such a relation.
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