A composite of infrared (shown as red), visible (green) and
ultraviolet (violet) images of the Crab Nebula, with IR enhanced and
visible/UV balanced to yield neutral star colours. Composite image made
with the Cosmic Coloring Compositor. Credit: NRAO. Large format: [ PNG ].
Work by Jane Greaves and Phil Cigan from Cardiff University, UK suggests
there may be a cosmic paucity of a chemical element essential to life.
Greaves has been searching for phosphorus in the universe, because of
its link to life on Earth. If this element is lacking in other parts of
the cosmos, then it could be difficult for extra-terrestrial life to
exist.
She explains "Phosphorus is one of just six chemical elements on
which Earth organisms depend, and it is crucial to the compound
adenosine triphosphate (ATP), which cells use to store and transfer
energy. Astronomers have just started to pay attention to the cosmic
origins of phosphorus, and found quite a few surprises. In particular,
phosphorus is created in supernovae - the explosions of massive stars -
but the amounts seen so far don't match our computer models. I wondered
what the implications were for life on other planets if unpredictable
amounts of phosphorus are spat out into space, and later used in the
construction of new planets."
The team used LIRIS on the William Herschel Telescope (WHT) to observe
infrared light from phosphorus and iron in the Crab Nebula, a supernova
remnant around 6,500 light-years away in the constellation of Taurus.
Spectrum of one position near the centre of the Crab Nebula, taken with
LIRIS at the WHT. The overlaid dotted line is a synthetic
representation of how the phosphorus line would appear if the Crab
Nebula had the same ratio of phosphorus to iron as the median value in
Cas A, the only other supernova remnant where phosphorus was studied
previously.
Credit: Jane Greaves and Phil Cigan. Large format: [ PNG ].
These preliminary results suggest that material blown out into space
could vary dramatically in chemical composition. Greaves remarks "The
route to carrying phosphorus into new-born planets looks rather
precarious. We already think that only a few phosphorus-bearing minerals
that came to the Earth - probably in meteorites - were reactive enough
to get involved in making proto-biomolecules."
She adds: "If phosphorus is sourced from supernovae, and then travels
across space in meteoritic rocks, I'm wondering if a young planet could
find itself lacking in reactive phosphorus because of where it was born?
That is, it started off near the wrong kind of supernova? In that case,
life might really struggle to get started out of phosphorus-poor
chemistry on another world otherwise similar to our own."Isaac Newton Group of Telescopes
More Information
"Paucity of phosphorus hints at precarious path for extraterrestrial life", European Week of Astronomy and Space Science press release, 3rd April 2018.
