We think of planets as essentially trapped children of their host stars.
However, space is strange and fickle, and objects don’t always follow the rules we think they do.
use J.W.S.T.In the beautiful setting of the Perseus star-forming nebula, astronomers have captured six “rogue” planet-sized objects that are not bound to any star and are free to roam interstellar space.
“We are exploring the limits of the star formation process.” Astrophysicist Adam Langeveld says: From Johns Hopkins University.
“If there is an object that appears young, JupiterCould it become a star under the right conditions? This is important context for understanding star and planet formation.”
There are several ways that objects in space can form. Stars are thought to form from the top down, with a clump of matter in a moderately dense cloud of dust and gas collapsing under gravity, accumulating more and more mass from a disk of material swirling around it, until the pressure and heat at its center are high enough to trigger hydrogen fusion.
At least some planets are thought to form in a bottom-up process, from material left in the disk after the star’s formation ends. In this scenario, chunks of material start to stick together electrostatically, then gravitationally, eventually accumulating enough material to form a differentiated core and mantle.
It’s unclear where the boundaries between these formation mechanisms lie, and this question is what prompted the researchers to call JWST a ” NGC 1333 Perseus is a region filled with a population of young stars newly forming from the gas within.
“We used Webb’s unprecedented sensitivity at infrared wavelengths to search for the faintest members of young star clusters and try to answer a fundamental question in astronomy: how much light does an object need to form like a star?” Astrophysicist Ray Jayawardene says: From Johns Hopkins University.
“The smallest stray objects forming like stars turn out to be comparable in mass to giant exoplanets orbiting nearby stars.”
Astronomers estimate that there are billions of rogue planets drifting through the galaxy. Most are thought to have formed the usual way: from food scraps swallowed by baby stars. Violent gravitational interactions can free these worlds from their stellar moorings and send them on starless adventures (or they can get captured by an alien planet’s gravity).
However, it is possible that some rogue planets may begin to develop in a similar way to stars. There is a known population of objects that form like stars, but do not have enough mass to undergo hydrogen fusion. These are brown dwarfs, with masses ranging from about 13 to 85 times that of Jupiter. These objects are massive enough to support the fusion of deuterium, a form of heavy hydrogen that requires lower pressures and temperatures for fusion. They glow, but are faint.
Modeling suggests that the upper mass limit for bottom-up planet formation by core accretion is Fewer than 10 JupitersMoreover, the NGC 1333 cluster is young, so such accretion will take some time, as will the gravitational interactions that push them out into a large, widespread galaxy.
So when JWST discovered six objects with masses between five and 10 times that of Jupiter, Langeveld and his team assumed they must have formed by gravitational collapse — an idea that was confirmed when they found tiny, star-like disks around the smaller objects.
“Our observations confirm that nature produces planetary-mass objects in at least two different ways: from the collapse of clouds of gas and dust, the way stars form, and from disks of gas and dust around young stars, such as Jupiter in our own solar system.” Jayawardene says:.
Interestingly, even though JWST is sensitive enough to detect much smaller objects, the researchers have not found any planets smaller than five Jupiter masses, suggesting that this mass is a limiting point: below this mass, planets likely need to form by core accretion.
The team’s findings show that such objects are numerous — accounting for 10 percent of all objects in the cluster they studied — and their discovery suggests tantalizing possibilities for blurring the boundaries between stars and their planets, and planets and their moons.
“These small objects with masses comparable to the giant planets could potentially form planets themselves.” Astrophysicist Alex Scholz says: “This could be a breeding ground for small planetary systems, much smaller than our solar system,” said researchers at the University of St Andrews in the UK.
This study Astronomical Journaland available arXiv.
