One of the greatest scientific discoveries of all time came with the invention of the spectroscope by Joseph Von Fraunhofer in 1814. It enabled us to look out at the universe and realize that the same basic building blocks that made you and I and all other life, were the same things that make up everything else in the cosmos. The tiny atoms in our bodies all started out at the center of a massive star billions of years ago. So naturally, when we talk about the odds of life forming elsewhere, we have to include a study of where exactly these key elements are in the universe, and how they have become distributed over time.
Using the Suzaku X-ray satellite, a team led by Aurora Simionescu, an astrophysicist at the Japan Aerospace Exploration Agency (JAXA), has mapped the chemical distribution in the nearby Virgo cluster of Galaxies.
The Virgo cluster is 54 Million light years away, with a membership of about 2,000 galaxies. The diffuse gas between the galaxies is so hot that it glows brightly in x-rays. Using Suzaku, Simionescu measured chemical compositions across four directions in the cluster, extending over 5 Million light years from its center. “Heavier chemical elements from carbon on up are produced and distributed into interstellar space by stars that explode as supernovae at the ends of their lifetimes,” Simionescu said.
Different types of supernovae produce different ratios of heavy elements. Massive stars form what we call core-collapse supernovae, as their mass eventually leads them to a cataclysmic event. Type 1a supernovae result from the explosion of a white dwarf star as it reaches a critical mass from merger or accretion. The former produces a range of elements from oxygen to silicon, while the latter produces heavier elements such as Iron and Nickel. As the supernovae explode and their elements are carried away, other mechanisms such as galactic outflows and mergers distribute these elements across a wide region.
If we look at the elements present in our Sun and solar system, we can figure out the ‘supernova recipe’ for our region of space, which turns out to be one type 1a for every five core-collapse supernovae. If we look at other places in the universe we can see if the recipe for life is ubiquitous, or if our precise mix is rare.
What do the results show? Simionescu and her colleagues detect iron, magnesium, silicon and sulfur all the way across a galaxy cluster. And the best part is that the elemental ratios are constant throughout the entire volume of the cluster, while also matching composition of the sun and most of the stars in our own galaxy.
“This means that elements so important to life on Earth are available, on average, in similar relative proportions throughout the bulk of the universe,” explained Simionescu. “In other words, the chemical requirements for life are common throughout the cosmos.”
Life just became a lot more likely.