Nav: Home

Universe's first life might have been born on carbon planets

June 07, 2016

Our Earth consists of silicate rocks and an iron core with a thin veneer of water and life. But the first potentially habitable worlds to form might have been very different. New research suggests that planet formation in the early universe might have created carbon planets consisting of graphite, carbides, and diamond. Astronomers might find these diamond worlds by searching a rare class of stars.

"This work shows that even stars with a tiny fraction of the carbon in our solar system can host planets," says lead author and Harvard University graduate student Natalie Mashian.

"We have good reason to believe that alien life will be carbon-based, like life on Earth, so this also bodes well for the possibility of life in the early universe," she adds.

The primordial universe consisted mostly of hydrogen and helium, and lacked chemical elements like carbon and oxygen necessary for life as we know it. Only after the first stars exploded as supernovae and seeded the second generation did planet formation and life become possible.

Mashian and her PhD thesis advisor Avi Loeb (Harvard-Smithsonian Center for Astrophysics) examined a particular class of old stars known as carbon-enhanced metal-poor stars, or CEMP stars. These anemic stars contain only one hundred-thousandth as much iron as our Sun, meaning they formed before interstellar space had been widely seeded with heavy elements.

"These stars are fossils from the young universe," explains Loeb. "By studying them, we can look at how planets, and possibly life in the universe, got started."

Although lacking in iron and other heavy elements compared to our Sun, CEMP stars have more carbon than would be expected given their age. This relative abundance would influence planet formation as fluffy carbon dust grains clump together to form tar-black worlds.

From a distance, these carbon planets would be difficult to tell apart from more Earth-like worlds. Their masses and physical sizes would be similar. Astronomers would have to examine their atmospheres for signs of their true nature. Gases like carbon monoxide and methane would envelop these unusual worlds.

Mashian and Loeb argue that a dedicated search for planets around CEMP stars can be done using the transit technique. "This is a practical method for finding out how early planets may have formed in the infant universe," says Loeb.

"We'll never know if they exist unless we look," adds Mashian.
-end-


Harvard-Smithsonian Center for Astrophysics

Related Planets Articles:

Ultracool dwarf and the 7 planets
Astronomers have found a system of seven Earth-sized planets just 40 light-years away.
ALMA measures size of seeds of planets
Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA), have for the first time, achieved a precise size measurement of small dust particles around a young star through radio-wave polarization.
Origin of minor planets' rings revealed
A team of researchers has clarified the origin of the rings recently discovered around two minor planets known as centaurs, and their results suggest the existence of rings around other centaurs.
Are planets setting the sun's pace?
The sun's activity is determined by the sun's magnetic field.
A better way to learn if alien planets have the right stuff
A new method for analyzing the chemical composition of stars may help scientists winnow the search for Earth 2.0.
More Planets News and Planets Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...