Milky Way rich in ‘greasy’ molecules

The Milky Way contains 10 billion trillion tonnes of 'greasy' matter, but not the kind that goes on your toast.

This magnificent 360-degree panoramic image, covering the entire southern and northern celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet. This gorgeous starscape serves as the first of three extremely high-resolution images featured in the GigaGalaxy Zoom project, launched by ESO within the framework of the International Year of Astronomy 2009 (IYA2009). The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The projection used in GigaGalaxy Zoom place the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image — almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc, marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy’s central bulge and its satellite galaxies. As filming extended over several months, objects from the Solar System came and went through the star fields, with bright planets such as Venus and Jupiter. For copyright reasons, we cannot provide here the full 800-million-pixel original image, which can be requested from Serge Brunier. The high resolution image provided here contains 18 million pixels.

Astronomers have found that there is an abundance of carbon-based ‘space grease’ in our Galaxy.

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Carbon is an essential ingredient for life as we know, but only half of the carbon between stars is in its purest form.

The rest is chemically bound in two forms, greasy (aliphatic) and mothball-like (aromatic).

A team at the University of New South Wales (UNSW) in Australia and Ege University in Turkey have mimicked in a laboratory the process by which these greasy molecules form.

By establishing how much of this greasy molecule there is in stardust, astronomers can infer how much of this element is present in the Universe.

“Combining our lab results with observations from astronomical observatories allows us to measure the amount of aliphatic carbon between us and the stars,” explains Professor Tim Schmidt of UNSW.

The team behind this study found that between a quarter and a half of available carbon is aliphatic, and that there are 100 of these atoms for every million hydrogen atoms.

This equates to 10 billion trillion trillion tonnes of greasy matter in the Milky Way.

Researchers conducted this experiment by putting carbon-containing plasma into a vacuum at low temperature.

An illustration showing the structure of a ‘greasy’ carbon molecule, with a backdrop showing the centre of the Milky Way, where it has been detected. Carbon is represented with grey spheres and hydrogen with white. Credit: D. Young (2011), The Galactic Center. Flickr – CreativeCommons
An illustration showing the structure of a ‘greasy’ carbon molecule, with a backdrop showing the centre of the Milky Way, where it has been detected. Carbon is represented with grey spheres and hydrogen with white.
Credit: D. Young (2011), The Galactic Center. Flickr – CreativeCommons

The material was then analysed by using magnetic resonance and spectroscopy to determine how abundant aliphatic carbon is.

This space grease however, is not the kind of grease that we would find on Earth and is not comparable to fats like butter.

“It’s dirty, likely toxic and only forms in the environment of interstellar space (and our laboratory,” says Schmidt.

“It’s also intriguing that organic material of this kind – material that gets incorporated into planetary systems – is so abundant.”

The teams next step is to determine how much aromatic carbon is abundant, which will involve more challenging work in the laboratory.


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