Starship Asterisk*

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GRB Illustration Credit: NASA/Swift/Mary Pat Hrybyk-Keith/John Jones

Cosmic explosions thousands of light-years away could shut down photosynthesis in the ocean at depths of up to 260 feet, a new study suggests. The calculations add to a growing body of research linking these great blasts, called gamma-ray bursts, with biological damage and even mass extinctions on Earth.

Gamma-ray bursts are tremendous explosions detonated during a massive star’s death throes. When stars eight times the mass of the sun or larger reach the end of their lives, they die in spectacular supernova explosions that can temporarily outshine entire galaxies.

Under certain conditions — astronomers aren’t exactly sure what — all that energy can be concentrated into a tight beam extending like a spotlight away from the star. These bright beams, known as gamma-ray bursts, can last up to 10 seconds, and carry energies equivalent to billions of nuclear bombs going off at once.

And according to the new research, phytoplankton would not enjoy them. In a paper published on the astronomy preprint site arXiv.org, biologist Liuba Penate of the Universidad Central de Las Villas in Cuba and colleagues model the marine food web from plankton up if a gamma-ray burst were to strike.

Earlier research showed that the burst would trigger an ultraviolet flash at the Earth’s surface. Incoming gamma rays would smack electrons off of atoms in the atmosphere, which would knock secondary electrons off nearby atoms and trigger a cascade of bright light.

• arXiv.org > astro-ph > arXiv:1007.2879 > 16 Jul 2010