7 Jul 2011

 

 

 

 

 

 

Hydrogen peroxide in the Rho Ophiuchi nebula

 

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.

 

by Michele Ferrara & Marcel Clemens

credit: ESO/S. Guisard