Jupiter is composed almost entirely of hydrogen and helium. The amounts of each closely conform to the theoretical quantities in the primordial solar nebula. But it also contains other heavier elements, which astronomers call metals. Even though metals are a small component of Jupiter, their presence and distribution tell astronomers a lot.
According to a new study, Jupiter’s metal content and distribution mean that the planet ate a lot of rocky planetesimals in its youth.
Is our Solar System comparable to other solar systems? What do other systems look like? We know from exoplanet studies that many other systems have hot Jupiters, massive gas giants that orbit extremely close to their stars. Is that normal, and our Solar System is the outlier?
One way of addressing these questions is to study the planet-forming disks around young stars to see how they evolve. But studying a large sample of these systems is the only way to get an answer. So that’s what a group of astronomers did when they surveyed 873 protoplanetary disks.
90 percent of all exoplanets discovered to date (there are now more than 5000 of them) orbit around stars the same size or smaller than our sun. Giant stars seem to lack planetary companions, and this fact has serious implications for how we understand solar system formation. But is the dearth of planets around large stars a true reflection of nature, or is there some bias inherent in how we look for exoplanets that is causing us to miss them? The recent discovery of two gas giants orbiting a giant star called µ2 Scorpii suggests it might be the latter.
Something ancient and primordial lurks in Earth’s core. Helium 3 (3He) was created in the first minutes after the Big Bang, and some of it found its way through time and space to take up residence in Earth’s deepest regions. How do we know this?
Astronomers have watched the young binary star system SVS 13 for decades. Astronomers don’t know much about how planets form around proto-binary stars like SVS 13, and the earliest stages are especially mysterious. A new study based on three decades of research reveals three potentially planet-forming disks around the binary star.
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.
Titanic collisions are the norm in young solar systems. Earth’s Moon was the result of one of those collisions when the protoplanet Theia collided with Earth some 4.5 billion years ago. The collision, or series of collisions, created a swirling mass of ejecta that eventually coalesced into the Moon. It’s called the Giant Impact Hypothesis.
Astronomers think that collisions of this sort are a common part of planet formation in young solar systems, where things haven’t settled down into predictability. But seeing any of these collisions around other stars has proved difficult.
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.
Planetary systems form out of the remnant gas and dust of a primordial star. The material collapses into a protoplanetary disk around the young star, and the clumps that form within the disk eventually become planets, asteroids, or other bodies. Although we understand the big picture of planetary formation, we’ve yet to fully understand the details. That’s because the details are complicated.
We’ve learned a thing or two about exoplanets in the past several years. One of the more surprising discoveries is that our solar system is rather unusual. The Sun’s worlds are easily divided into small rocky planets and large gas giants. Exoplanets are much more diverse, both in size and composition.