Planetary Formation Archives

February 4, 2022February 4, 2022 by Evan Gough

A Second Generation of Planets can Form Around a Dying Star

An illustration of a protoplanetary disk. The solar system formed from such a disk. Astronomers suggest this birthplace was protected by a larger filament of molecular gas and dust early in history. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

When young stars coalesce out of a cloud of molecular hydrogen, a disk of leftover material called a protoplanetary disk surrounds them. This disk is where planets form, and astronomers are getting better at peering into those veiled environments and watching embryonic worlds take shape. But young stars aren’t the only stars with disks of raw material rotating around them.

Some old, dying stars also have disks. Can a second generation of planets form under those conditions?

January 17, 2022January 17, 2022 by Evan Gough

A Star Passed too Close and Tore Out a Chunk of a Protoplanetary Disk

Scientists have captured an intruder object disrupting the protoplanetary disk—birthplace of planets—in Z Canis Majors (Z CMa), a star in the Canis Majoris constellation. This artist’s impression shows the perturber leaving the star system, pulling a long stream of gas from the protoplanetary disk along with it. Observational data from the Subaru Telescope, Karl G. Jansky Very Large Array, and Atacama Large Millimeter/submillimeter Array suggest the intruder object was responsible for the creation of these gaseous streams, and its “visit” may have other as yet unknown impacts on the growth and development of planets in the star system. Credit: ALMA (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)

When it comes to observing protoplanetary disks, the Atacama Large Millimetre/sub-millimetre Array (ALMA) is probably the champion. ALMA was the first telescope to peer inside the almost inscrutable protoplanetary disks surrounding young stars and watch planets forming. ALMA advanced our understanding of the planet-forming process, though our knowledge of the entire process is still in its infancy.

According to new observations, it looks like chaos and disorder are part of the process. Astronomers using ALMA have watched as a star got too close to one of these planet-forming disks, tearing a chunk away and distorting the disk’s shape.

What effect will it have on planetary formation?

November 19, 2021November 19, 2021 by Evan Gough

There’s So Much Pressure at the Earth’s Core, it Makes Iron Behave in a Strange Way

New observations of the atomic structure of iron reveal it undergoes "twinning" under extreme stress and pressure. Image Credit: SLAC National Accelerator Laboratory

It’s one of nature’s topsy-turvy tricks that the deep interior of the Earth is as hot as the Sun’s surface. The sphere of iron that resides there is also under extreme pressure: about 360 million times more pressure than we experience on the Earth’s surface. But how can scientists study what happens to the iron at the center of the Earth when it’s largely unobservable?

With a pair of lasers.

September 28, 2021September 28, 2021 by Evan Gough

The Early Solar System was Messier and More Violent Than Previously Believed

This artwork shows a rocky planet being bombarded by comets. Image credit: NASA/JPL-Caltech

Our conventional models of planet formation may have to be updated, according to a pair of new papers.

Accretion is the keyword in current planet formation theory. The idea is that the planets formed out of the solar nebula, the material left over after the Sun formed. They did this through accretion, where small particles accumulate into more massive objects. These massive boulder-sized objects, called planetesimals, continued to merge together into larger entities, sometimes through collisions. Eventually, through repeated mergers and collisions, the inner Solar System was populated by four rocky planets.

But the new research suggests that the collisions played out much differently than thought and that objects collided with each other several times, in a series of hit and runs, before merging. This research fills some stubborn holes in our current understanding.

September 7, 2021September 7, 2021 by Paul M. Sutter

Many Sunlike Stars Gobbled up Some of Their Planets

New research shows that other sunlike stars in our galaxy aren’t so kind to their planets. Up to a quarter of them may consume planets before they even establish a solar system. That consumption leaves behind a distinct chemical fingerprint in the stars, which can help researchers understand how common planetary systems are…and how often they get destroyed.

July 28, 2021July 28, 2021 by Andy Tomaswick

This is how you get Tatooines. Binary Star Planet Formation

One of the less appreciated aspects of George Lucas’ vision for Star Wars was that he predicted the existence of planets in binary star systems years before we saw even the first exoplanet. Now a team from the University of Cambridge and the Max Planck Institute for Extra-terrestrial Physics have found how exactly those planets can form without being torn apart by their accompanying suns.

July 13, 2021September 10, 2021 by Andy Tomaswick

The Sun is Mellow Yellow Today. Billions of Years Ago? Not So Much

Planetary formation theory has been undergoing a lot of changes recently, with an ever expanding litany of events that can potentially impact it. Everything from gravity to magnetic fields seems to impact this complex process. Now scientists want to add another confounding factor – massive solar flares thousands of times more powerful than the most powerful we have ever observed from the Sun.

July 11, 2021July 11, 2021 by Andy Tomaswick

Does Mercury Have a big Iron Core Because it’s so Close to the Sun’s Magnetic Field?

Magnetic fields are great for lots of things – directing explorers, levitating trains, and containing nuclear fusion reactions are just an example of what these invisible forces can do. Now we can ascribe another feature to magnetic fields – they can give planets a rocky core.

July 6, 2021July 6, 2021 by Andy Tomaswick

Astronomers see an Accretion Disk Where Planets are About to Form

Planet formation is notoriously difficult to study. Not only does the process take millions of years, making it impossible to observe in real time, there are myriad factors that play into it, making it difficult to distinguish cause and effect. What we do know is that planets form from features known as protoplanetary disks, which are made up of gas and dust surrounding young stars. And now a team using ALMA have found a star system that has a protoplanetary disk and enough variability to help them nail down some details of how exactly the process of planet formation works.

June 7, 2021June 7, 2021 by Paul M. Sutter

Planets may Start Forming Before the Star is Even Finished

Planets form from the accumulation of countless grains of dust swirling around young stars. New computer simulations have found that planets begin forming earlier than previously thought, when a planet’s star hasn’t even finished forming yet.