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A nebula to dye for!

The Rho Ophiuchi clouds

The colourful Rho Ophiuchi star formation region, about 400 light-years from Earth, contains very cold (around -250 degrees Celsius), dense clouds of cosmic gas and dust, in which new stars are being born. Astronomers using the APEX telescope have detected hydrogen peroxide molecules in the area marked with the red circle.

MOLECULES OF HYDROGEN PEROXIDE have been found for the first time in interstellar space. The discovery gives clues about the chemical link between two molecules critical for life: water and oxygen.

On Earth, hydrogen peroxide plays a key role in the chemistry of water and ozone in our planet’s atmosphere, and is familiar for its use as a disinfectant or to bleach hair blonde. It’s also sometimes used as rocket fuel!

An international team of astronomers made the discovery with the Atacama Pathfinder Experiment telescope (APEX), situated on the 5,000-metre-high Chajnantor plateau in the Chilean Andes.

They studied a region in our galaxy close to the star Rho Ophiuchi, about 400 light-years away. The region contains very cold (around -250 degrees Celsius), dense clouds of cosmic gas and dust, in which new stars are being born.

The clouds are mostly made of hydrogen, but contain traces of other chemicals, and are prime targets for astronomers hunting for molecules in space.

Telescopes such as APEX, which make observations of light at millimetre- and submillimetre-wavelengths, are ideal for detecting the signals from these molecules.

Now, the team has found the characteristic signature of light emitted by hydrogen peroxide, coming from part of the Rho Ophiuchi clouds.

“We were really excited to discover the signatures of hydrogen peroxide with APEX,” says Per Bergman, astronomer at Onsala Space Observatory in Sweden. “We knew from laboratory experiments which wavelengths to look for, but the amount of hydrogen peroxide in the cloud is just one molecule for every ten billion hydrogen molecules, so the detection required very careful observations.”

Bergman is lead author of the study, which is published in the journal Astronomy & Astrophysics.

APEX telescope

The APEX telescope studies the cosmos at millimetre- and submillimetre-wavelengths—ideal for detecting certain molecules.

Clue to the origin of water

Hydrogen peroxide (H2O2) is a key molecule for both astronomers and chemists. Its formation is closely linked to two other familiar molecules, oxygen and water, which are critical for life. Because much of the water on our planet is thought to have originated in space, scientists are keen to understand how it is formed.

Hydrogen peroxide is thought to form in space on the surfaces of cosmic dust grains—very fine particles similar to sand and soot—when hydrogen (H) is added to oxygen molecules (O2). A further reaction of the hydrogen peroxide with more hydrogen is one way to produce water (H2O).

This new detection of hydrogen peroxide will therefore help astronomers better understand the formation of water in the Universe.

“We don’t understand yet how some of the most important molecules here on Earth are made in space. But our discovery of hydrogen peroxide with APEX seems to be showing us that cosmic dust is the missing ingredient in the process,” says Bérengère Parise, head of the Emmy Noether research group on star formation and astrochemistry at the Max-Planck Institute for Radio Astronomy in Germany, and a co-author of the paper.

To work out just how the origins of these important molecules are intertwined will need more observations of Rho Ophiuchi and other star-forming clouds with future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA)—and help from chemists in laboratories on Earth.

The new discovery may also help astronomers understand another interstellar mystery—why oxygen molecules are so hard to find in space. It was only in 2007 that oxygen molecules were first discovered in space, by the satellite Odin.

APEX is a collaboration between the Max-Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and European Southern Observatory. The telescope is operated by ESO.

Wide field view of the Rho Ophiuchi star formation

A full view of the Rho Ophiuchi star formation region, which is a favourite of amateur astronomers. Rho Ophiuchi itself is the bright star near the top of the image. The bright yellowish star in the bottom left is Antares, one of the brightest stars in the sky. Below and to Antares’ right is the globular star cluster Messier 4.

Download wallpapers of the Rho Ophiuchi clouds:

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Adapted from information issued by ESO / S. Guisard (www.eso.org/~sguisard) / H.H.Heyer.

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Space observatory’s first results

The first scientific results from the European Space Agency’s (ESA) Herschel infrared space observatory are revealing previously hidden details of star formation.

New images show thousands of distant galaxies furiously building stars and beautiful star-forming clouds draped across the Milky Way. One picture even catches an ‘impossible’ star in the act of formation.

Herschel is the largest astronomical telescope ever to be placed into space. The diameter of its main mirror is four times larger than any previous infrared space telescope and one and a half times larger than Hubble.

As stars begin to form, the surrounding dust and gas is warmed up to a few tens of degrees above absolute zero and starts to emit at far-infrared wavelengths. The Earth’s atmosphere completely blocks the majority of these wavelengths and thus observations from space are necessary.

Using its unprecedented resolution and sensitivity, Herschel is conducting a census of star-forming regions in our Galaxy.

“Before Herschel, it was not clear how the material in the Milky Way came together in high enough densities and at sufficiently low temperatures to form stars,” says Sergio Molinari, Istituto di Fisica dello Spazio Interplanetario, Roma.

Herschel is also a prime instrument for detecting one of the smallest forms of matter: molecules. It has made the first discovery in space of a new ‘phase’ of water. It is electrically charged and unlike the more familiar phases, namely solid ice, liquid water and gaseous steam, it does not occur naturally on Earth.

In the birth clouds surrounding young stars, however, where ultraviolet light is pumping through the gas, this irradiation can knock an electron out of the water molecule, leaving it with an electrical change.

“These are still early days for Herschel and this is just the beginning of all the science that we will get from this mission in the years to come,” says Goran Pilbratt, ESA Herschel Project Scientist.