In all of scientific modeling, the models attempting to replicate planetary and solar system formation are some of the most complicated. They are also notoriously difficult to develop. Normally they center around one of two formative ideas: planets are shaped primarily by gravity or planets are shaped primarily by magnetism. Now a new theoretical model has been developed by a team at the University of Zurich (UZH) that uses math from both methodologies to inform the most complete model yet of planetary formation.Continue reading “Magnetic Fields Help Shape the Formation of New Planets”
200 light-years away from Earth, there’s a K-type main-sequence star named TOI (TESS Object of Interest) 178. When Adrian Leleu, an astrophysicist at the Center for Space and Habitability of the University of Bern, observed it, it appeared to have two planets orbiting it at roughly the same distance. But that turned out to be incorrect. In fact, six exoplanets orbit the smallish star.
And five of those six are locked into an unexpected orbital configuration.Continue reading “Exoplanetary System Found With 6 Worlds in Orbital Resonance”
It seems unlikely that an ocean could persist on a world that never gets closer than 30 astronomical units from the Sun. But that’s the case with Pluto. Evidence shows that it has a sub-surface ocean between 100 to 180 km thick, at the boundary between the core and the mantle. Other Kuiper Belt Objects may be similar.
But time might be running out for these buried oceans, which will one day turn to ice.Continue reading “Pluto and Other Kuiper Belt Objects Started Out With Water Oceans, and Have Been Slowly Freezing Solid for Billions of Years”
Astronomy is advancing to the point where we can see planets forming around young stars. This was an unthinkable development only a few years ago. In fact, it was only two years ago that astronomers captured the first image of a newly-forming planet.
Now there are more and more studies into how planets form, including a new one with fifteen images of planet-forming disks around young stars.Continue reading “More Pictures of Planet-Forming Disks Around Young Stars”
Astronomers like observing distant young stars as they form. Stars are born out of a molecular cloud, and once enough of the matter in that cloud clumps together, fusion ignites and a star begins its life. The leftover material from the formation of the star is called a circumstellar disk.
As the material in the circumstellar disk swirls around the now-rotating star, it clumps up into individual planets. As planets form in it, they leave gaps in that disk. Or so we think.Continue reading “Are the Gaps in These Disks Caused by Planets?”
There are around 61,000 meteorites on Earth, or at least that’s how many have been found. Out of those, about 200 of them are very special: they came from Mars. And those 200 meteorites have been important clues to how Mars formed in the early Solar System.Continue reading “Mars Was Hit By a Lot of Protoplanets Early in its History, Taking Longer to Form than Previously Thought.”
According to the most widely accepted theory of planet formation (the Nebular Hypothesis), the Solar System began roughly 4.6 billion years ago from a massive cloud of dust and gas (aka. a nebula). After the cloud experienced gravitational collapse at the center, forming the Sun, the remaining gas and dust fell into a disk that orbited it. The planets gradually accreted from this disk over time, creating the system we know today.
However, until now, scientists have wondered how dust could come together in microgravity to form everything from stars and planets to asteroids. However, a new study by a team of German researchers (and co-authored by Rutgers University) found that matter in microgravity spontaneously develops strong electrical charges and stick together. These findings could resolve the long mystery of how planets formed.Continue reading “Planets Started Out From Dust Clumping Together. Here’s How”
Discovering new things in space is a regular occurrence. Astronomers keep finding more distant objects in the outer reaches of the Solar System. Worlds like ‘The Goblin,’ ‘FarOut,’ and ‘FarFarOut‘ are stretching the limits of what our Solar System actually is.
But finding new things in the inner Solar System is rare.Continue reading “New Ring of Dust Discovered in the Inner Solar System”
The hunt for other planets in our galaxy has heated up in the past few decades, with 3869 planets being detected in 2,886 systems and another 2,898 candidates awaiting confirmation. Though the discovery of these planets has taught scientists much about the kinds of planets that exist in our galaxy, there is still much we do not know about the process of planetary formation.
To answer these questions, an international team recently used the Atacama Large Millimeter/submillimeter Array (ALMA) to conduct the first large-scale, high-resolution survey of protoplanetary disks around nearby stars. Known as the Disk Substructures at High Angular Resolution Project (DSHARP), this program yielded high-resolution images of 20 nearby systems where dust and gas was in the process of forming new planets.
What if our Solar System had another generation of planets that formed before, or alongside, the planets we have today? A new study published in Nature Communications on April 17th 2018 presents evidence that says that’s what happened. The first-generation planets, or planet, would have been destroyed during collisions in the earlier days of the Solar System and much of the debris swept up in the formation of new bodies.
This is not a new theory, but a new study brings new evidence to support it.
The evidence is in the form of a meteorite that crashed into Sudan’s Nubian Desert in 2008. The meteorite is known as 2008 TC3, or the Almahata Sitta meteorite. Inside the meteorite are tiny crystals called nanodiamonds that, according to this study, could only have formed in the high-pressure conditions within the growth of a planet. This contrasts previous thinking around these meteorites which suggests they formed as a result of powerful shockwaves created in collisions between parent bodies.
“We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet.” – study co-author Philippe Gillet
Models of planetary formation show that terrestrial planets are formed by the accretion of smaller bodies into larger and larger bodies. Follow the process long enough, and you end up with planets like Earth. The smaller bodies that join together are typically between the size of the Moon and Mars. But evidence of these smaller bodies is hard to find.
One type of unique and rare meteorite, called a ureilite, could provide the evidence to back up the models, and that’s what fell to Earth in the Nubian Desert in 2008. Ureilites are thought to be the remnants of a lost planet that was formed in the first 10 million years of the Solar System, and then was destroyed in a collision.
Ureilites are different than other stony meteorites. They have a higher component of carbon than other meteorites, mostly in the form of the aforementioned nanodiamonds. Researchers from Switzerland, France and Germany examined the diamonds inside 2008 TC3 and determined that they probably formed in a small proto-planet about 4.55 billion years ago.
Philippe Gillet, one of the study’s co-authors, had this to say in an interview with Associated Press: “We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet.”
According to the research presented in this paper, these nanodiamonds were formed under pressures of 200,000 bar (2.9 million psi). This means the mystery parent-planet would have to have been as big as Mercury, or even Mars.
The key to the study is the size of the nanodiamonds. The team’s results show the presence of diamond crystals as large as 100 micrometers. Though the nanodiamonds have since been segmented by a process called graphitization, the team is confident that these larger crystals are there. And they could only have been formed by static high-pressure growth in the interior of a planet. A collision shock wave couldn’t have done it.
But the parent body of the ureilite meteorite in the study would have to have been subject to collisions, otherwise where is it? In the case of this meteorite, a collision and resulting shock wave still played a role.
The study goes on to say that a collision took place some time after the parent body’s formation. And this collision would have produced the shock wave that caused the graphitization of the nanodiamonds.
The key evidence is in what are called High-Angle Annular Dark-Field (HAADF) Scanning Transmission Electron Microscopy (STEM) images, as seen above. The image is two images in one, with the one on the right being a magnification of a part of the image on the left. On the left, dotted yellow lines indicate areas of diamond crystals separate from areas of graphite. On the right is a magnification of the green square.
The inclusion trails are what’s important here. On the right, the inclusion trails are highlighted with the orange lines. They clearly indicate inclusion lines that match between adjacent diamond segments. But the inclusion lines aren’t present in the intervening graphite. In the study, the researchers say this is “undeniable morphological evidence that the inclusions existed in diamond before these were broken into smaller pieces by graphitization.”
To summarize, this supports the idea that a small planet between the size of Mercury and Mars was formed in the first 10 million years of the Solar System. Inside that body, large nanodiamonds were formed by high-pressure growth. Eventually, that parent body was involved in a collision, which produced a shock wave. The shock wave then caused the graphitization of the nanodiamonds.
It’s an intriguing piece of evidence, and fits with what we know about the formation and evolution of our Solar System.