Sun's fickle heart may leave us cold Options

[SigurRosFan]

Interesting ...

- Sun's fickle heart may leave us cold

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The favoured frequencies allow the sun's core temperature to oscillate around its average temperature of 13.6 million kelvin in cycles lasting either 100,000 or 41,000 years. Ehrlich says that random interactions within the sun's magnetic field could flip the fluctuations from one cycle length to the other.

These two timescales are instantly recognisable to anyone familiar with Earth's ice ages: for the past million years, ice ages have occurred roughly every 100,000 years. Before that, they occurred roughly every 41,000 years.
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[edstrick]

The time scales are going to be very dependent on details of the model<s>. This is an interesting modeling job, but I am very very dubious that they've gotten ALL of the important and relevant physics right enough for the conclusions to be anywhere secure.

The only way we'll really nail down any solar variability climate influence is precision interplanet <not interplanetary> climate history comparisions, probably primarily beteween earth polar and marine core records and martian polar core records.

Titan, Triton and Pluto may have ultimately-useful solar activity records but Titan may mess it's up too much and Triton and Pluto are too severely unknown to have much idea what they may record. Their best records may be of the solar systems travels through the interstellar medium, particular arm-passages where the system will sometines encounter molecular clouds.

[AndyG]

The average time required for a core-produced photon to escape the photosphere seems to be around 100,000 to 200,000 years (depending on where you read it!)

Surely, therefore, the photons born in any particular similarly-termed core cycle would be statistically smeared to mush by the time we're looking at solar output on climate?

Andy

[ngunn]

Fortunately for us those core produced photons don't escape the photosphere!

[Rob Pinnegar]

The fact that this guy's model produces two possible periods that just *happen* to precisely coincide with both of the known ice-age periods is fishy, to say the least. Given the complexity of the physics involved, you'd think he'd be off by a couple of thousand years either way in both cases -- close enough to show the connection, but not bang-on.

As for solar-core photons: The figure I've heard quoted for how long core energy takes to reach the surface is 500,000 years, but that may be outdated as it is probably from my undergraduate days (1988-1992).

I've looked at this New Scientist magazine a few times, and haven't been greatly impressed. They seem willing to print just about anything. I don't think we really needed a tabloid version of Scientific American.

[AndyG]

Rob...my reading of some of the last few Scientific Americans would suggest IT is already a tabloid version of the magazine I remember fondly from 20+ years ago.

Ngunn...ha! Yes - but difficult to put into shorthand the 10^25-or-so hops or so for the energy created in the core photons to escape.

Andy

[ngunn]

the magazine I remember fondly from 20+ years ago.

and I from 40+. It was founded in 1956 and has been the general UK reader's prime resource for keeping up with science news and views ever since. They do report controversial ideas but not without context and usually with commendable editorial balance.

I agree with the point about the 'predicted' solar time cycles being suspiciously precise. There aren't many computer models that don't have a few floating parameters, and when you know the answers in advance . . .

[dvandorn]

It seems to me that since photons take so long to make their way out from the Sun's core to the photosphere, *any* variability in the Sun's output must be due to the electromagnetic conditions at the surface, where they are eventually "let out."

And we already know that the Sun's magnetic field is rather highly variable over even short periods... it takes rather less of a leap of logic than the authors of this paper seem to take to assume that long-term periodicities are driven by the same magnetic field fluctuations that drive the short-term variations.

-the other Doug