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Titel |
On the astronomical origin of the Hallstatt oscillation found in radiocarbon and climate records throughout the Holocene |
VerfasserIn |
Nicola Scafetta, Franco Milani, Antonio Bianchini, Sergio Ortolani |
Konferenz |
EGU General Assembly 2017
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 19 (2017) |
Datensatznummer |
250146077
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Publikation (Nr.) |
EGU/EGU2017-10075.pdf |
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Zusammenfassung |
An oscillation with a period of about 2100-2500 years, the Hallstatt
cycle, is found in cosmogenic radioisotopes ($^{14}C$ and $^{10}Be$)
and in paleoclimate records throughout the Holocene. This oscillation
is typically associated with solar variations, but its primary physical
origin remains uncertain. Herein we show strong evidences for an astronomical
origin of this cycle. Namely, this oscillation is coherent to a repeating
pattern in the periodic revolution of the planets around the Sun:
the major stable resonance involving the four Jovian planets - Jupiter,
Saturn, Uranus and Neptune - which has a period of about $p=2318$
yr. Inspired by the Milankovi{\'c}'s theory of an astronomical origin
of the glacial cycles, we test whether the Hallstatt cycle could derive
from the rhythmic variation of the circularity of the solar system
disk assuming that this dynamics could eventually modulate the solar
wind and, consequently, the incoming cosmic ray flux and/or the interplanetary/cosmic
dust concentration around the Earth-Moon system. The orbit of the
planetary mass center (PMC) relative to the Sun is used as a proxy.
We analyzed how the instantaneous eccentricity vector of this virtual
orbit varies from 13,000 B. C. to 17,000 A. D.. We found that it undergoes
a kind of pulsations and clearly presents rhythmic contraction and
expansion patterns with a 2318 yr period together with a number of
already known faster oscillations associated to the planetary orbital
stable resonances. There exists a quasi $\pi/2$ phase shift between
the 2100-2500 yr oscillation found in the $^{14}C$ record and that
of the calculated eccentricity function. Namely, at the Hallstatt-cycle
time scale, a larger production of radionucleotide particles occurs
while the Sun-PMC orbit evolves from more elliptical shapes ($e\approx0.598$)
to more circular ones ($e\approx0.590$), that is while the orbital
system is slowly imploding or bursting inward; a smaller production
of radionucleotide particles occurs while the Sun-PMC orbit evolves
from more circular shapes ($e\approx0.590$) to a more elliptical
ones ($e\approx0.598$), that is while the orbital system is slowly
exploding or bursting outward. Since at this timescale the PMC eccentricity
variation is relatively small ($e=0.594\pm0.004$), the physical origin
of the astronomical 2318 yr cycle is better identified and distinguished
from faster orbital oscillations by the times it takes the PMC to
make pericycles and epicycles around the Sun and the times it takes
to move from minimum to maximum distance from the Sun within those
arcs. These particular proxies reveal a macroscopic 2318 yr period
oscillation, together with other three stable outer planet orbital
resonances with periods of 159, 171 and 185 yr. This 2318 yr oscillation
is found to be spectrally coherent with the $\varDelta^{14}C$ Holocene
record with a statistical confidence above 95\%, as determined by
spectral analysis and cross wavelet and wavelet coherence analysis.
At the Hallstatt time scale, maxima of the radionucleotide production
occurred when, within each pericycle-apocycle orbital arc, the time
required by the PMC to move from the minimum to the maximum distance
from the Sun varies from about 8 to 16 years while the time required
by the same to move from the maximum to the minimum distance from
the Sun varies from about 7 to 14 years, and viceversa. Thus, we found
that a fast expansion of the Sun-PMC orbit followed by a slow contraction
appears to prevent cosmic rays to enter within the system inner region
while a slow expansion followed by a fast contraction favors it. Similarly,
the same dynamics could modulate the amount of interplanetary/cosmic
dust falling on Earth. Indeed, many other stable orbital resonance
frequencies (e.g. at periods of 20 yr, 45 yr, 60 yr, 85 yr, 159-171-185
yr, etc.) are found in radionucleotide, solar, aurora and climate
records, as determined in the scientific literature. Thus, the result
supports a planetary theory of solar and/or climate variation that
has recently received a renewed attention. In our particular case,
the rhythmic contraction and expansion of the solar system driven
by a major resonance involving the movements of the four Jovian planets
appear to work as a gravitational/electromagnetic pump that increases
and decreases the cosmic ray and dust densities inside the inner region
of the solar system, which then modulate both the radionucleotide
production and climate change by means of a cloud/albedo modulation.
\newline
Citation: Scafetta, N., Milani, F., Bianchini, A., Ortolani, S.: 2016. On the astronomical origin of the Hallstatt oscillation
found in radiocarbon and climate records throughout the Holocene. Earth-Science Reviews 162, 24--43. DOI: 10.1016/j.earscirev.2016.09.004. |
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