- 4195 -
NEPTUNE SIZE - planet and how galaxies form? -Astronomers found a scorching Neptune-size
planet that is way too massive for
astronomers to explain. Astronomers have
unexpectedly discovered the heaviest Neptune-like planet yet. This planet is more
than four times the mass of our solar system's Neptune, yet it remains a mystery how the world might
have formed.
------------------ 4195 - NEPTUNE SIZE - planet and how galaxies form
- Between rocky
planets about the mass of Earth and gas giants the mass of Jupiter, which holds
more than 300 times our planet's mass, there are worlds the size of Neptune,
which holds just about 17 times Earth's mass.
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- Astronomers have
found that Neptune-size planets display a great deal of variety, ranging from
icy worlds clad in thick atmospheres of hydrogen and helium, such as the
Neptune we know and love, to very dense planets made of either substantial
amounts of water or bundles of rock wrapped in thinner atmospheres. ( Such as the exoplanets HD 95338 b,
TOI-849 b and TOI-2196 b).
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- In the new study,
astronomers investigated TOI-1853, an orange dwarf star about 80 percent of the
sun's mass and diameter. TOI-1853 is located about 544 light-years from Earth
in the Boötes constellation. Using NASA's Transiting Exoplanet Survey Satellite
(TESS), they discovered an exoplanet around a star they dubbed TOI-1853 b.
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- The newfound
planet sits about 50 times closer to its star than Earth is to the sun,
completing one orbit in just 30 hours instead of the 365 days it takes Earth.
The planet's extreme proximity to its host star also makes it searing hot at
about 2,200 degrees Fahrenheit.
-
- The newfound
planet's diameter is about 3.46 times larger than Earth's, making it a bit
smaller than Neptune, which is about 3.8 times wider than Earth. However, upon
using Italy's Galileo National Telescope on the island of La Palma to measure
the strength of TOI-1853 b's gravitational tug on its star, the scientists
estimated this exoplanet's mass is about 73 times greater than Earth's. This
means its mass is nearly equal to the mass of Saturn, which is about 95 times
more massive than Earth.
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- TOI-1853 b is about
six times denser than Neptune and nearly twice as dense as Earth. This makes it
the densest Neptune-size planet known to date.
The discovery of TOI-1853 b implies that large planets can have
surprising amounts of heavy elements, much more than previously thought. Neptunian planets show an astonishing
variety of density and compositions, but we didn't believe they could be so
compact.
-
- Exoplanets that
orbit their stars as closely as TOI-1853 b does are either rocky planets with
diameters less than twice Earth's or so-called hot Jupiters, gas giants sizing
in at more than 10 times Earth's diameter. Mysteriously, scientists have only
found a few hot Neptunes such as TOI-1853 b, a phenomenon dubbed the "hot
Neptune desert."
-
- Conventional
theories of planetary formation would suggest that TOI-1853 b should not
exist. One possibility for the planet's
formation is that it was born catastrophically from collisions "between
large proto-planets such as super-Earths.
These huge impacts would have removed part of the original atmosphere
and water, leaving mostly rock behind. If this is the case, TOI-1853b is likely
to have a brother not too far away.
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- Another possible
explanation for the planet's origin is that it was a giant planet in a highly
"eccentric" or oval-shaped orbit. This would have led to regular
close encounters with its star, causing the world to lose much of its
atmosphere and leaving behind a dense core. These stellar flybys could also
have eventually made the planet's orbit less eccentric over time, explaining
the trajectory's currently circular shape.
-
- The researchers
suggested TOI-1853 b may be mostly rocky and surrounded by a small envelope of
hydrogen and helium that makes up 1 percent of the planet's mass. Another
possibility is that TOI-1853 b may be composed of about 50 percent rock and 50
percent water. If true, it would mean
its atmosphere may be rich in water vapor due to the planet's extreme
heat
-
- To really figure
out TOI-1853 b's composition, scientists would have to analyze its atmosphere.
However, this will likely prove difficult even with NASA's extraordinarily
powerful James Webb Space Telescope, since "we expect its atmosphere to be
very thin, if existent at all".
-
- Understanding the
nature of this planet will definitely be challenging.
-
- The Milky Way
wasn't always a spiral and astronomers may finally know why it
'shape-shifted'. Our Milky Way galaxy
did not always possess its familiar spiral appearance.
-
- The evolution of
galaxies from one shape to another takes place is a process known as “galactic
speciation” . The research shows that clashes and subsequent mergers between
galaxies are a form of "natural selection" that drives the process of
cosmic evolution.
-
- This means that the
Milky Way's history of cosmic violence is not unique to our home galaxy. Astronomy
now has a new anatomy sequence and finally an evolutionary sequence in which
galaxy speciation is seen to occur through the inevitable marriage of galaxies
ordained by gravity.
-
- Galaxies come in
an array of shapes. Some, like the Milky Way, are composed of arms of
well-ordered stars revolving in a spiral shape around a central concentration
or "bulge" of stellar bodies. Other galaxies like Messier 87 (M87)
are composed of an ellipse of billions of stars chaotically buzzing around a disordered
central concentration.
-
- Since the 1920s,
astronomers have classified galaxies based on a sequence of varying galaxy
anatomy called the "Hubble sequence." Spiral galaxies like ours sit
at one end of this sequence, while elliptical galaxies like M87 sit at the
other. Bridging the gap between the two are elongated sphere-shaped galaxies,
lacking spiral arms, called lenticular galaxies.
-
- But what this
widely-used system has lacked until now were the evolutionary paths that link
one galaxy shape to another. Reshaping
galactic evolution revealed the existence of two different types of bridging
lenticular galaxies: One version that is old and lacks dust, and the other that
is young and rich in dust.
-
- When dust-poor
galaxies accrete gas, dust, and other matter, the disk that surrounds their
central region is disrupted, with this disruption creating a spiral pattern
radiating out from their hearts. This creates spiral arms, which are over-dense
rotating regions that create gas clumps as they turn, triggering collapse and
star formation.
-
- The dust-rich
lenticular galaxies, on the other hand, are created when spiral galaxies
collide and merge. This is indicated by the fact that spiral galaxies have a
small central spheroid with extending spiral arms of stars, gas and dust. Young
and dusty lenticular galaxies have notably more prominent spheroids and black
holes than spiral galaxies and dust-poor lenticular galaxies.
-
- The surprising
result of this is the conclusion that spiral galaxies like the Milky Way
actually lie between dust-rich and dust-poor lenticular galaxies on the Hubble
sequence.
The history of the Milky Way is believed to be punctuated
with a series of "cannibalistic" events in which it devoured smaller
surrounding satellite galaxies to grow.
-
- In addition to
this, our galaxy's cosmic "acquisitions" also included it accreting
other material and gradually transforming from a dust-poor lenticular galaxy to
the spiral galaxy we know today.
-
- Our galaxy is set
for a dramatic merger with its closest large galactic neighbor, the Andromeda
galaxy, in between 4 billion and 6 billion years. This collision and merger
will see the spiral arm pattern of both galaxies erased and the new research
indicates that the daughter galaxy created by this union is likely to be a
dust-rich lenticular galaxy still possessing a disk, albeit without a spiral
structure carved through it.
-
- Should the Milky
Way-Andromeda daughter galaxy encounter a third, dust-rich lenticular galaxy
and merge with it, then the disk-like aspects of both galaxies will also be
wiped clean. This would create an elliptical-shaped galaxy without the ability
to harbor cold gas and dust clouds.
-
- Just as this new
galaxy will carry the story of its evolution for astronomers in the far-future,
the dust-poor lenticular galaxies could serve as fossil records of the
processes that transformed old and common disk-dominated galaxies in the early
universe.
-
- This could help
explain the discovery by the James Webb Space Telescope (JWST) of a massive
spheroid-dominated galaxy just 700 million years after the Big Bang. The new
research could indicate that the merging of elliptical galaxies is a process
that could explain the existence of some of the universe's most massive
galaxies, which sit at the heart of clusters of over 1,000 galaxies.
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-
October 22, 2023 NEPTUNE SIZE -
planet and how galaxies form?
4195
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