TY - JOUR

T1 - Evidence of nearby supernovae affecting life on Earth

A1 - Svensmark,Henrik

AU - Svensmark,Henrik

PB - Wiley-Blackwell Publishing Ltd.

PY - 2012

Y1 - 2012

N2 - Observations of open star clusters in the solar neighbourhood are used to calculate local supernova (SN) rates for the past 510 Myr. Peaks in the SN rates match passages of the Sun through periods of locally increased cluster formation which could be caused by spiral arms of the Galaxy. A statistical analysis indicates that the Solar system has experienced many large short-term increases in the flux of Galactic cosmic rays (GCR) from nearby SNe. The hypothesis that a high GCR flux should coincide with cold conditions on the Earth is borne out by comparing the general geological record of climate over the past 510 Myr with the fluctuating local SN rates. Surprisingly, a simple combination of tectonics (long-term changes in sea level) and astrophysical activity (SN rates) largely accounts for the observed variations in marine biodiversity over the past 510 Myr. An inverse correspondence between SN rates and carbon dioxide (CO2) levels is discussed in terms of a possible drawdown of CO2 by enhanced bio-productivity in oceans that are better fertilized in cold conditions – a hypothesis that is not contradicted by data on the relative abundance of the heavy isotope of carbon, 13C.

AB - Observations of open star clusters in the solar neighbourhood are used to calculate local supernova (SN) rates for the past 510 Myr. Peaks in the SN rates match passages of the Sun through periods of locally increased cluster formation which could be caused by spiral arms of the Galaxy. A statistical analysis indicates that the Solar system has experienced many large short-term increases in the flux of Galactic cosmic rays (GCR) from nearby SNe. The hypothesis that a high GCR flux should coincide with cold conditions on the Earth is borne out by comparing the general geological record of climate over the past 510 Myr with the fluctuating local SN rates. Surprisingly, a simple combination of tectonics (long-term changes in sea level) and astrophysical activity (SN rates) largely accounts for the observed variations in marine biodiversity over the past 510 Myr. An inverse correspondence between SN rates and carbon dioxide (CO2) levels is discussed in terms of a possible drawdown of CO2 by enhanced bio-productivity in oceans that are better fertilized in cold conditions – a hypothesis that is not contradicted by data on the relative abundance of the heavy isotope of carbon, 13C.

KW - Astrobiology

KW - Earth

KW - Supernovae

KW - General

KW - Cosmic rays

KW - Open clusters and associations

KW - Galaxy

KW - Structure

UR - ftp://ftp2.space.dtu.dk/pub/Svensmark/MNRAS_Svensmark2012.pdf

U2 - 10.1111/j.1365-2966.2012.20953.x

DO - 10.1111/j.1365-2966.2012.20953.x

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

VL - 423

SP - 1234

EP - 1253

ER -