Nav: Home

Exoplanet interiors have Earth-like geochemistry

October 17, 2019

The interiors of some exoplanets have Earth-like geochemistry, according to a new study, which finds that extrasolar rocks share similar levels of oxidation, or oxygen fugacity, to those in the Solar System. The results suggest that some of the rocky exoplanets orbiting distant stars have similar internal properties to Earth and Mars. Alexandra Doyle and colleagues were able to probe the geochemistry of distant rocks by evaluating their elemental remains, imprinted in the atmospheres of white dwarfs after rocky bodies crashed into them. Most rocky materials in the Solar System have a high degree of oxidation, known as oxygen fugacity (fO2), which reflects conditions during the earliest stages of protoplanetary rock formation around the Sun. fO2 influences a planet's overall geochemical and geophysical properties - including the composition of any atmosphere it produces. However, determining these properties in exoplanets is both difficult and often unreliable, so it has been uncertain whether the same processes which oxidized planet-forming material in our Solar System occurred elsewhere, in solar systems around other stars. A white dwarf (WD) is the dense, exhausted core of a dead star; due to its strong gravitational pull, WD surface atmospheres should be composed almost entirely of the lightest elements, hydrogen and helium. However, some WDs have been identified with atmospheres "polluted" by heavier elements, including magnesium, iron and oxygen, introduced by rocky exoplanets and asteroids that have crashed into the WD. Spectroscopic observations of six polluted WDs allowed Doyle et al. to measure the constituent elements of these extrasolar rocks and to determine the abundance of oxidized iron within the rocks. The results probe the bulk composition of the former exoplanets, including their interiors. They find that rocky bodies that once orbited these long-dead stars had high fO2, similar to Earth, Mars and the asteroids in our Solar System, but unlike Mercury.

American Association for the Advancement of Science

Related Solar System Articles:

Pressure runs high at edge of solar system
Out at the boundary of our solar system, pressure runs high.
What a dying star's ashes tell us about the birth of our solar system
A UA-led team of researchers discovered a dust grain forged in a stellar explosion before our solar system was born.
What scientists found after sifting through dust in the solar system
Two recent studies report discoveries of dust rings in the inner solar system: a dust ring at Mercury's orbit, and a group of never-before-detected asteroids co-orbiting with Venus, supplying the dust in Venus' orbit.
Discovered: The most-distant solar system object ever observed
A team of astronomers has discovered the most-distant body ever observed in our solar system.
Discovery of the first body in the Solar System with an extrasolar origin
Asteroid 2015 BZ509 is the very first object in the Solar System shown to have an extrasolar origin.
First interstellar immigrant discovered in the solar system
A new study has discovered the first known permanent immigrant to our solar system.
A star disturbed the comets of the solar system in prehistory
About 70,000 years ago, when the human species was already on Earth, a small reddish star approached our solar system and gravitationally disturbed comets and asteroids.
Scientists detect comets outside our solar system
Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets -- comets outside our solar system -- orbiting a faint star 800 light years from Earth.
Does the organic material of comets predate our solar system?
The Rosetta space probe discovered a large amount of organic material in the nucleus of comet 'Chury.' In an article published by MNRAS on Aug.
Tracking a solar eruption through the solar system
Ten spacecraft, from ESA's Venus Express to NASA's Voyager-2, felt the effect of a solar eruption as it washed through the solar system while three other satellites watched, providing a unique perspective on this space weather event.
More Solar System News and Solar System Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at