THE ices in Comet Hale-Bopp are not formed from the raw stuff of interstellar
gas, according to astronomers in the US.
Michael DiSanti of NASA鈥檚 Goddard Space Flight Center in Greenbelt, Maryland,
and his colleagues conducted a spectroscopic survey of the comet. They found
that the nucleus contains 12 per cent more carbon monoxide than water鈥攁
smaller fraction than found in the cold areas of interstellar molecular clouds,
but comparable to levels in the clouds that give birth to stars (Nature, vol 399, p 662).
The observations also suggest that the ices underwent some form chemical
processing鈥攑robably driven by light from the newborn Sun鈥攂efore they
were swept up into the growing comet.
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