- 4621 - PLANET DISCOVERED - size of the Earth? This Earth-Sized Planet is 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?
----------------------- 4621 - PLANET DISCOVERED - size of the Earth?
- Astronomers are investigating 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.
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- This study holds the potential to help
researchers better understand the processes responsible for this, along with
continuing to challenge our understanding of exoplanetary architectures.
-
- 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 progenitor for those planet engulfment
events. The tidal disruption of rocky planets allows us to probe their interior
composition and compare with Earth.
-
- The researchers analyzed TOI-6255 b, whose
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.
-
- This 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.
-
- 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.
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- 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.
But what is the significance of TOI-6255 b being an Earth-sized planet as
opposed to a Jupiter-sized planet, or larger?
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- 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, 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 24, 2024 PLANET DISCOVERED
- size of the Earth? 4621
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--------------------- --- Monday, November 25,
2024
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