Useful as a disinfectant and an old way of bleaching your hair,
hydrogen peroxide (H2O2)
has now been found for the first time in interstellar space, within
the nebula that surrounds the star Rho Ophiuchi. About 400 light
years away, this nebula is a gigantic mass of gas and dust within
which new stars are being born. This cloud is particularly well
known among amateur astrophotographers for its beautiful range of
colours.
In the above image, taken from the Paranal observatory site
with a 10 cm diameter telescope, Rho Ophiuchi is the bright star
near the top edge of the frame, while the red circle indicates the
region observed by the APEX (Atacama Pathfinder Experiment)
telescope. This sub-millimetre radio telescope is a precursor
instrument for the Atacama Large Millimetre/sub-millimetre Array
(ALMA) that will consist of a total of 64 radio dishes, and will
soon begin preliminary observations.
Using APEX, a research team led
by Per Bergman (Onsala Space Observatory, Sweden) detected a
spectral line of hydrogen peroxide. This is a considerable
observational achievement given that the abundance of hydrogen
peroxide molecules is 10 billion times lower than that of hydrogen,
the gas that dominates the makeup of all nebulae.
The importance of
hydrogen peroxide is its connection to two other molecules that are
essential for life, water and oxygen. Given that it is thought that
much of the water found on Earth was originally formed in space, it
would be nice to know how this water was formed.
It seems likely
that the dust found in interstellar clouds is a key ingredient, as
this can act as a catalyst for reactions between oxygen and
hydrogen. Of course, at the densities with which we are familiar on
Earth these two elements have no need for a catalyst (their reaction
actually powers rockets!) but at the incredibly low interstellar
densities chemical reactions are much harder. The detection of
molecules like hydrogen peroxide and the study of the formation of
water in space will see tremendous progress when ALMA begins its
science observations later this year.
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