- 4616
- EXOPLANETS - in
other solar systems? - How many additional “Exoplanets” are in
known systems? One thing we’ve learned
in recent decades is that exoplanets are surprisingly common. So far, we’ve
confirmed nearly 6,000 planets, and we have evidence for thousands more.
-
----------------------------------------- 4616 - EXOPLANETS - in other solar systems?
- Most of these exoplanets were discovered
using the transit method. though we there are other methods as well. Many stars
are known to have multiple planets, such as the TRAPPIST-1 system with seven
Earth-sized worlds.
-
- But even within known planetary systems
there could be planets we’ve overlooked. Perhaps their orbit doesn’t pass in
front of the star from our vantage point, or the evidence of their presence is
buried in data noise.
-
- Rather than combing through the
observational data trying to extract more planets from the noise, the authors
suggest that we look at the orbital dynamics of known systems to see if planets
might be possible between the planets we know.
-
- Established systems are millions or
billions of years old, so their planetary orbits must be stable on those
timescales. If the planets of a system are “closely packed,” then adding new
planets to the mix would cause the system to go all akilter. If the system is
“loosely packed,” then we could add hypothetical planets between the others,
and the system would still be dynamically stable.
-
- To show how this would work, the authors
consider seven planetary systems discovered by the Transiting Exoplanet Survey
Satellite (TESS) known to have two planets. Since it isn’t likely that a system
has only two planets, there is a good chance they have others. The team then
ran thousands of simulations of these systems with hypothetical planets,
calculating if they could remain stable over millions of years.
-
- They found that for two of the systems,
extra planets (other than planets much more distant than the known ones) could
be ruled out on dynamical grounds. Extra planets would almost certainly
destabilize the systems. But five of the systems could remain stable with more
planets. That doesn’t mean those systems have more planets, only that they
could.
-
- One of the things this work shows is that
most of the currently known exoplanetary systems likely have yet-undiscovered
worlds. This approach could also help us sort systems to determine which ones
might deserve a further look. We are still in the early stages of discovery,
and we are gathering data with incredible speed. We need tools like this so we
aren’t overwhelmed by piles of new data.
-
- It is a good thing we found this
Earth-Sized Planet now. It’s about to be destroyed. Astronomers have confirmed
the existence of exoplanets with extremely small orbits around their stars. But
what about exoplanets that get close enough to be devoured by their star, and
what if it’s an Earth-sized exoplanet?
-
- Researchers investigated an Earth-sized
exoplanet with an orbital period of only 5.7 hours, known as
“ultra-short-period” (USP) exoplanets, that could eventually experience what’s
known as “tidal disruption”, resulting in its devourment by its star.
-
- Tidal disruption could be a potential fate
of rocky planets. It seems like about
10 percent of sun-like stars might have engulfed their rocky planets. This
system “TOI-6255” is the best-known for those planet engulfment events. The
tidal disruption of rocky planets allows us to probe their interior composition
and compare with Earth.
-
- “TOI-6255 b” radius is 1.08 and mass is
1.44 of Earth’s and located just over 65.2 light-years from Earth. However,
while being Earth-sized holds promise for life, TOI-6255 b’s 5.7-hour orbit not only make this
exoplanet far too hot for life as we know it to exist, but this also means its
orbit takes it dangerously close to what’s known as “Roche limit”.
-
- The “Roche limit” is the distance a smaller
object can orbit a larger object until the larger object’s gravity tears the
smaller object to pieces, along with TOI-6255 b also experiencing the tidal disruption, which is a common
occurrence throughout the universe including black holes.
-
- This planet is doomed for tidal disruption
in 400Myr which is short on cosmic scale (13Gyr). The planet is also tidally
distorted to be football like in shape (10 percent deviation from sphere), in
comparison Earth’s tidal distortion due to the moon is only 1e-7 [0.0000001]
level.
-
- The “orbital phase curve” study of this
planet could confirm that it is indeed tidally distorted. We know what the
phase curve should look like for a spherical planet, tidally distorted planet
has a strong deviation from that. We can also see if the surface of the planet
is covered by lava pool as would be expected on a planet this hot.
-
- USPs are exoplanets whose orbits are less
than one day and whose masses are less than 2x the Earth. Only about 100 USPs have been discovered with
a 2014 study estimating approximately 0.5 percent exist around Sun-like stars
and a 2019 study discussing their bulk composition (i.e., mass of its iron core
and mantle).
-
- Given their extremely short orbit, these
worlds are likely too hot for life as we know it to exist, and along with USPs
are the familiar “hot Jupiters” who orbit their stars in only a few days and
astronomers estimate their population is in the hundreds.
-
- These worlds are Jupiter-sized or larger
gas planets and are also potentially far too hot for life as we know it to
exist. Planets similar to Earth in
size are most likely rocky i.e. mostly made of iron core and silicate mantle.
They show us what terrestrial planets in other planetary systems are made of.
Jupiter-sized planets are most certainly covered by thick hydrogen and helium
atmospheres. Jupiter-sized planets are unlikely to harbor life.
-
- While TOI-6255 b isn’t due for disassembly
for another 400 million years, watching any exoplanet get ripped to shreds by
its host star could provide important insights regarding the planet’s exterior
and interior compositions, thus helping us better understand the similarities
between exoplanets and planets within our own solar system.
-
- These unique worlds and their extremely
tight orbits have challenged our understanding of solar system architecture
throughout our Milky Way Galaxy, as Mercury is the closest planet to our Sun,
and it still takes 88 days to complete one orbit.
-
- One similarity between our solar system and
exoplanetary systems is the Roche limit.
Tidal disruption could be a potential fate of rocky planets. Tidal disruption of planets is minimal in
our solar system. However, the rings of Saturn are thought to originate from
tidal disruption of satellites around Saturn. Tidal forces are strongly
dependent on orbital separation, only objects with the shortest orbital period
experience significant tides.
-
-
November , 2024 EXOPLANETS - in
other solar systems? 4616
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--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for
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------ “Jim Detrick” -----------
--------------------- --- Saturday, November 23,
2024
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