Carbon and oxygen rich stardust sheds new light on origin of elements of life

March 13th, 2009 - 12:50 pm ICT by ANI  

Washington, March 13 (ANI): An international research team has found evidence that some stars in the center of the Milky Way galaxy have both carbon and oxygen in the dust that surrounds them, which sheds new light on the origin of the elements of life.

Scientists have long expected to find carbon-rich stars in our galaxy because we know that significant quantities of carbon must be created in many such stars, but carbon had not previously shown up in the clouds of gas around these stars, said Matthew Bobrowsky, an astrophysicist in the University of Marylands department of physics.

As a star burns hotter and hotter, the hydrogen gas that originally made up almost all of its mass is converted, through nuclear fusion, first to helium, and then to progressively heavier elements.

The hottest region in the core fuses together the heaviest elements. And these can reach the surface of the star only when its life is almost over.

The Big Bang produced only hydrogen and helium. Heavier elements like carbon and oxygen only come from getting cooked up in stars, Bobrowsky said. Nuclear reactions in stars created the heavier elements found in life as we know it, he added.

The team of scientists used the Spitzer Space Telescope to view each star and its surrounding clouds of dust and particles, called a planetary nebulae.

The researchers measured the light emitted by the stars and the surrounding dust and were able to identify carbon compounds based on the wavelengths of light emitted by the stars.

Looking in an area at the center of the Milky Way called the Galactic Bulge, the team observed 26 stars and their planetary nebulae and found 21 with carbon signatures.

But, the scientists did not just find carbon around these stars; they also found oxygen in these 21 dust clouds, revealing a surprising mixture of ingredients for space dust.

The finding of carbon and oxygen in the dust clouds surrounding stars suggests a recent change of chemistry in this population of stars.

Stars in the center of the Milky Way are old and metal-rich with a high abundance of heavy elements, Bobrowsky said. They are different in chemical composition than those found in the disc, farther out from the center, he added.

Studying the chemistry of these stars helps scientists learn how the matter that makes up our earth and other planets in our galaxy left its stellar birthplaces long ago.

If we want to understand how our galaxy, and the stars, planets and life in it, came to be the way they are, we need to understand the creation of the chemical elements of which they are composed, Bobrowsky said. (ANI)

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