Stellar explosion in Earth's proximity, eons ago
Discovery of iron-60 and manganese-53 substantiates supernova 2.5 million years ago

Date:
September 30, 2020
Source:
Technical University of Munich (TUM)
Summary:
When the brightness of the star Betelgeuse dropped dramatically a
few months ago, some observers suspected an impending supernova -
a stellar explosion that could also cause damage on Earth. While
Betelgeuse has returned to normal, physicists have found evidence
of a supernova that exploded near the Earth around 2.5 million
years ago.



FULL STORY ==========================================================================
When the brightness of the star Betelgeuse dropped dramatically a few
months ago, some observers suspected an impending supernova -- a stellar explosion that could also cause damage on Earth. While Betelgeuse has
returned to normal, physicists from the Technical University of Munich
(TUM) have found evidence of a supernova that exploded near the Earth
around 2.5 million years ago.


==========================================================================
The life of stars with a mass more than ten times that of our sun ends
in a supernova, a colossal stellar explosion. This explosion leads to
the formation of iron, manganese and other heavy elements.

In layers of a manganese crust that are around two and a half million
years old a research team led by physicists from the Technical
University of Munich has now confirmed the existence of both iron-60
and manganese-53.

"The increased concentrations of manganese-53 can be taken as the "smoking
gun" -- the ultimate proof that this supernova really did take place,"
says first author Dr. Gunther Korschinek.

While a very close supernova could inflict massive harm to life on
Earth, this one was far enough away. It only caused a boost in cosmic
rays over several thousand years. "However, this can lead to increased
cloud formation," says co- author Dr. Thomas Faestermann. "Perhaps
there is a link to the Pleistocene epoch, the period of the Ice Ages,
which began 2.6 million years ago." Ultra-trace analysis Typically,
manganese occurs on earth as manganese-55. Manganese-53, on the other
hand, usually stems from cosmic dust, like that found in the asteroid belt
of our solar system. This dust rains down onto the earth continuously; but
only rarely do we perceive larger specks of dust that glow as meteorites.

New sediment layers that accumulate year for year on the sea floor
preserve the distribution of the elements in manganese crusts and sediment samples. Using accelerator mass spectrometry, the team of scientists
has now detected both iron-60 and increased levels of manganese-53 in
layers that were deposited about two and a half million years ago.

"This is investigative ultra-trace analysis," says Korschinek. "We are
talking about merely a few atoms here. But accelerator mass spectrometry
is so sensitive that it even allows us to calculate from our measurements
that the star that exploded must have had around 11 to 25 times the size
of the sun." The researchers were also able to determine the half-life
of manganese-53 from comparisons to other nuclides and the age of the
samples. The result: 3.7 million years. To date, there has only been a
single measurement to this end worldwide.


========================================================================== Story Source: Materials provided by
Technical_University_of_Munich_(TUM). Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. G. Korschinek, T. Faestermann, M. Poutivtsev, A. Arazi, K. Knie, G.

Rugel, A. Wallner. Supernova-Produced Mn53 on Earth. Physical
Review Letters, 2020; 125 (3) DOI: 10.1103/PhysRevLett.125.031101 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200930144417.htm

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