Supernovae and solar cycles found in Ice Cores

[Mk]

http://arxiv.org/abs/0902.3446
So apparently gamma rays from nearby supernovae produce nitrogen oxide in the atmosphere. The team took 122-meter-long cores from Dome Fuji station in Antarctica and found three nitrogen oxide spikes in the 11th century. They think they know what two of them are, but the third is a mystery. They also saw a 10-year variation in background nitrogen oxide, and sulphate spikes corresponding to volcanic eruptions between 100 and 1300 AD.

Abstract
Ice cores are known to be rich in information regarding past climates, and the possibility that they record astronomical phenomena has also been discussed. Rood et al. were the first to suggest, in 1979, that nitrate ion (NO3-) concentration spikes observed in the depth profile of a South Pole ice core might correlate with the known historical supernovae (SNe), Tycho (AD 1572), Kepler (AD 1604), and SN 1181 (AD 1181). Their findings, however, were not supported by subsequent examinations by different groups using different ice cores, and the results have remained controversial and confusing. Here we present a precision analysis of an ice core drilled in 2001 at Dome Fuji station in Antarctica. It revealed highly significant three NO3- spikes dating from the 10th to the 11th century. Two of them are coincident with SN 1006 (AD 1006) and the Crab Nebula SN (AD 1054), within the uncertainty of our absolute dating based on known volcanic signals. Moreover, by applying time-series analyses to the measured NO3- concentration variations, we discovered very clear evidence of an 11-year periodicity that can be explained by solar modulation. This is one of the first times that a distinct 11-year solar cycle has been observed for a period before the landmark studies of sunspots by Galileo Galilei with his telescope. These findings have significant consequences for the dating of ice cores and galactic SN and solar activity histories.

 

[mgb_phys]

I'd be amazed if gamma rays from a SN in the crab produced a measurable change in the rate of NOx production (did 1987A produce anything similair?)

Still it's a funny old world

 

[Skyhunter]

This is one of the first times that a distinct 11-year solar cycle has been observed for a period before the landmark studies of sunspots by Galileo Galilei with his telescope.

This just confirms what was already known, NO₃ production is tied to the flux in solar magnetic field.

 

[mgb_phys]

This just confirms what was already known, NO₃ production is tied to the flux in solar magnetic field.

Similairly N14->C14 production is tied to the solar cycle and has to be calibrated out for C14 dating, but that doesn't prove that a SN 6500 lyr away can produce NOx

 

[Xnn]

Moreover, using available knowledge of the radiation chemistry processes induced
by γ-rays and important neutral chemical reactions of nitrogen in the stratosphere,
we estimated the order of magnitude of nitrogen oxide production under a simple
assumption that the SN γ-ray energy is equipartitioned within an atmospheric column at
the altitudes between 25 and 45 km. We found that SN 1006 could produce nitrogen
oxides about one order of magnitude higher than that from solar radiation, and that the
Crab Nebula of the same order of magnitude. From the energetics point of view, it is
thus reasonable that the SN spikes with large amplitudes appear above the solar cycle
background trend.

So, the 1006 SN was an order of magnitude higher than the sun. SN's are known to produce as much energy in a short time frame as the sun does over its entire lifetime. They do that by becoming extremely hot just before exploding. So, it may not be too surprising that their spectrum shifts dramatically towards higher energies which would include γ-rays.