- 4395 - FREE -FLOATING PLANETS - In 2021 using the James Webb Space Telescope (JWST), astronomers made the startling discovery of some free-floating, planetary-mass objects in the Orion nebula that threw their ideas of planet and star formation into doubt. And now, new research has further deepened the mystery around these so-called “Jupiter-mass binary objects”, or JuMBOs.
------------------------- 4395 -
FREE -FLOATING PLANETS?
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- JuMBOs aren't stars, but aren't really
planets either. This nebula is in a
star birthing region, also known as “Messier 45”, and sits around 1,350 light
years from Earth.
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- Despite the fact that astronomers found 40
pairs of JuMBOs, only one pair of these strange objects was seen to be emitting
radio waves. Now we have this strong
radio emission, and it is not clear what is producing it.
-
- The radio signal was seen coming from both
components of "JuMBO 24." Both components seem to have around 11
times the mass of Jupiter, making them the largest of their kind seen by the
JWST, with the others having masses between 3 and 8 times that of the solar
system's most massive planet.
-
- The signal was significantly stronger than
radio signals associated with objects similar to JuMBOs, or brown dwarfs. Brown
dwarfs are objects born in the same way as stars, but that fail to gather
enough mass to trigger the fusion of hydrogen to helium at their cores like
your standard star does.
-
- This failure to kickstart the process that
defines a star in its main sequence lifetime has led to brown dwarfs, with
masses between 13 to 75 times the mass of Jupiter, receiving the unfortunate
nickname of "failed stars."
-
- With regular stars and brown dwarfs, there
are mechanisms that explain radio emissions. For JuMBOs, we have no mechanism
to explain this very strong radio emission.
JuMBOs are hot, gassy, and relatively small bodies that exist in pairs,
a combination that defies common observations of binary stars. Normally,
scientists believe only the most massive stars prefer life in binary pairings;
the smaller a stellar body is, the less likely it is to be found in a binary
partnership.
-
- Binary stars are born when overly dense
patches in a disk of gas and dust fragments collapse and gather mass, forming
twin stars. Around 75% of massive stars exist found in binaries, with this
percentage dropping to 50% for stars around the size of the sun and 25% for the
smallest stars.
-
- The chance of finding brown dwarfs in
binaries is close to zero. That means JuMBOs, which are under the mass limit
for brown dwarfs, shouldn't really exist in binaries if they are indeed formed
like stars.
-
- If these planetary-mass objects can't
form according to current star formation models, they are born like
planets. Maybe, but JuMBO pairings are
equally difficult to explain if they are created like planets, which form from
leftover material in the same disks of gas and dust that birthed their parent
stars.
-
- Some planets are known to be ejected from
around their host star as a result of internal or external gravitational
effects, such as encounters with other star systems. From there, those worlds
become "rogue planets" and wander the cosmos without a parent star,
just like how JuMBOs in Orion appear to be orphans. However, the process that
creates these orphan planets is so violent that it should split apart any
gravitational bound planet pairs.
-
- The ejection mechanism can't account for
why Jupiter-like planets would have been ejected together. That means the
planetary evolution route can explain how JuMBOs came to be, but not why they
still have their binary partners. Even if such a thing could happen on some
occasions, there aren't just one or two JuMBO pairings in Orion. There are 42.
-
- JuMBOs in Orion become even more
challenging to explain when considering the fact that some of the binaries they
dwell in are extremely widely spaced. A few JuMBOs appear to even be separated
by as much as 300 times the distance between the Earth and the sun. Others fall
as far apart as the width of the whole solar system, meaning they are very
weakly gravitationally bound.
-
- The other JuMBOs could also be emitting
radio waves because their components are smaller than the two 11-Jupiter mass
objects in the JuMBO 24 binary.
-
- Deeper observations could also reveal the
velocity of the JuMBOs in the sky with relation to the Orion nebula. If the
JuMBOs are moving rapidly, this would suggest that they formed like planets
around stars and were ejected from these systems. On the other hand, if these
curious celestial bodies are almost stationary in relation to Orion, this would
imply they are created from massive clouds of collapsing gas and dust like
stars.
-
- Either explanation would prompt a rethink
of how stars and planets form and evolve in their respective systems.
-
- If JuMBOs had moons, one could speculate
that life could exist In a subsurface ocean like it is suspected in Europa,
Ganymede, and Enceladus. However, the objects in Orion are young at just a few
million years old [compared to our 4.6 billion-year-old solar system]. There probably has not been enough time for
life to appear on these moons if they exist.
-
- In the unlikely event these objects or
moons around them could support life, researchers chasing alien organisms on
JuMBO 24 would also have to explain why radio emissions are coming from both
components of this strange binary, not just one.
-
- While JuMBOs may be the astronomical
discovery of the 2020s and are fascinating targets for scientists who want to
understand the formation of stars and planets better, they may not be great
targets for scientists investigating the possibility of life outside the solar
system.
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-
March 19, 2023 FREE -FLOATING PLANETS 4395
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2024
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