Slash Boxes

SoylentNews is people

posted by janrinok on Wednesday October 02 2019, @09:37PM   Printer-friendly
from the where-did-you-come-from? dept.

Arthur T Knackerbracket has found the following story:

A gas giant orbiting a tiny red dwarf star thirty light years away has left astronomers baffled because it's not supposed to exist, according to a study published in Science on Thursday.

Under the standard model of planet formation, the object known as GJ 3512 b should have never been born as it’s considered almost impossible for low-mass stars like GJ 3512 to harbour massive gas planets. The protoplanetary disk, a rotating jumble of gas and dust around a young star, simply doesn’t contain enough matter to form hefty gaseous planets when the star is small.

Current theories suggest that planets are grown from smaller bits of debris known as planetesimals glomming together in protoplanetary disks. In order to create a gas giant, a sufficient amount of these planetesimals have to stick together to form a solid core. The rocky centre accumulates gas from the surrounding disk by its gravitational pull, Markus Nielbock, a spokesperson at the Max Planck Institute of Astronomy, who was not explicitly involved in the research, explained to The Register.

“If the disk isn't heavy enough, however, there is not sufficient solid material around that can form those planetesimals quickly enough before they migrate through the disk into the inner regions and eventually fall into the star.”

So how did all that material go into forming gas giants like GJ 3512 b? The global team of researchers believe that the protoplanetary disk must have directly collapsed under its own gravity instead.

In this scenario, GJ 3512 b sprung from material gathered near the outer regions of the disk - beyond 10 astronomical units, or ten times the distance between the Sun and Earth. The temperatures here are very cold, about 10 kelvin (-263 °C), and the outward thermal pressure of the disk cannot counteract the inward gravitational compression. The disk, therefore, collapses under its own weight.

The surrounding material forms a solid core massive enough to accrue gas in the disk so that a planet like GJ 3512 b is possible. These types of disks are described as gravitationally unstable disks. But even this idea doesn’t completely explain the strange system.

[...] There is evidence, however, that the system once contained a third planet alongside the GJ 3512 b and the second planet GJ 3512 c, speculated by the researchers. A series of gravitational instabilities led to the ejection of the third planet and brought GJ 3512 b’s orbit closer to it star and more eccentric. It currently completes an orbit in 204 days.

The exoplanet isn’t really that remarkable on its own. But when the researchers consider it alongside its star, they’re flummoxed.

Related: When Dwarfs Give Birth To Giants

Original Submission

This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 0) by Anonymous Coward on Thursday October 03 2019, @01:00AM (1 child)

    by Anonymous Coward on Thursday October 03 2019, @01:00AM (#902115)

    Indeed. The known universe contains enough star systems to display many bizarre systems. Odds, statistics, probabilities, and WTF?!?!? Demon Murphy(of Murphy's Law fame) rollin' the dice.

    Alternate hypothesis: maybe 'once in a million chance' of capture of a rogue gas giant kicked out of somewhere else.

    At our current level of tech, we are basically just getting good detail about our own yard, and moderate detail about our own block, anything beyond that strained metaphor, and it's all fuzzy.
    It's getting better all the time though, and I have a strong feeling that my tired old self will continue to be amazed in the coming years/decades(hopefully).

    "To boldly go where no man has gone before..." That will happen someday, arguably soon, as it seems to be hardwired into us to 'see what's over the next hill'.

  • (Score: 2) by takyon on Thursday October 03 2019, @01:22AM

    by takyon (881) <> on Thursday October 03 2019, @01:22AM (#902123) Journal

    As our telescopes improve and we start to find all of the Earth, Mars, Mercury, and Pluto-sized objects around stars within 10-100 light years, it should become more clear what a typical planetary system looks like.

    But even then, the situation could be different closer to the violent center of the galaxy, or around more exotic objects like neutron stars (closest known are 400+ light years away).

    [SIG] 10/28/2017: Soylent Upgrade v14 []