Dec 21, 2023 01:53 AM
(This post was last modified: Dec 21, 2023 02:10 AM by C C.)
Forbidden Worlds? Planet-forming theory clashes with observation
https://www.centauri-dreams.org/2023/12/...servation/
EXCERPTS: The past few decades have not been easy on planet formation theories. Concepts formed on the antiquated Copernican speculation, the commonality of star systems identical to the Solar System, have given way to the strangeness and variety uncovered by Kepler, Hubble, and the other space borne telescopes. The richness of the planetary arrangements defies easy explanation.
Penn State University researchers uncovered another oddity challenging current understanding of stellar system development. Study of the LHS 3154 system reveals a planet so massive in comparison to its star that generally accepted theories of planet formation cannot explain the existence of the planet,..
[...] In current theories, stars form from condensing large clouds of gas and dust into smaller volumes. After the star forms, the left-over gas and dust which is a much smaller fraction of the original cloud, settles into a disk around the new star. From this much smaller mass, planets will condense, completing the star system. In these theories, the star consumes the major proportion of the progenitor clouds.
The Sun, for example, contains an estimated 99.8% of the mass of the Solar System. Only 0.2% is left over for the eight planets, various moons and asteroids.
The mass ratio comparing LHS 3154b to LHS 3154 is 117 times greater than mass ratio comparing the Earth to the Sun. LHS 3154b probably is Neptune-like in composition, completes its orbit in 3.7 Earth days and, the researchers believe, is a very rare world. Typically M-dwarves host small rocky bodies rather than gas giants.
According to current theories, once the star formed, there should not have been enough mass to form a planet as large as LHS 3154b...
[...] Not all mysteries are confined to M-dwarfs. A sun-like star, an infant of 14 million years some 360 light years from Earth, hosts a gas giant six times more massive than Jupiter, that orbits the star at a distance twenty times greater than the distance separating Jupiter and the Sun. ... The large distance from YSES 2b to the star does not fit either of the two most well-known models describing large gaseous planet formation...
[...] Observations by the current generation of space-borne telescopes have upset the theories of planet formation. Hot Jupiters, worlds orbiting pulsars, odd arrangements of worlds, super Earths, and wandering worlds flung close to a star then flying back have complicated the ideas of Laplace...... (MORE - missing details)
Giant space rock made Earth’s ocean boil but also helped early life
https://www.washingtonpost.com/science/2...xsxITNCnHw
EXCERPTS: The young Earth got beat up a lot, including one day 3.26 billion years ago when a rock four times the size of Mount Everest slammed into the planet. Scientists believe that the rock, which was much bigger than the Chicxulub object that ended the reign of the dinosaurs, probably landed in the ocean, since Earth had barely begun to form continents.
The collision was so violent it boiled off the top layer of that ocean and, near the impact site, created a tsunami as high as a New York skyscraper. Molten rock rained from the sky. The atmosphere was choked with ash and dust. The planet descended into darkness.
But it wasn’t all bad.
That was the counterintuitive implication of three presentations at the American Geophysical Union’s fall meeting in San Francisco this month. The scientists, working independently, found that the bludgeoning of young Earth by giant space rocks may have primed the planet to be more congenial to life.
[...] For example, the tremendous tsunami that was probably created by the impact 3.26 billion years ago would have mixed up the water column in the global ocean and brought more iron, a key nutrient for metabolism, to shallow seas. Other nutrients would have eroded into the ocean from land masses, according to Drabon.
Nick Wogan, a scientist at NASA Ames Research Center who presented at AGU, described how early impacts would have given Earth a “hot steam atmosphere” but also might have triggered life-relevant chemistry.
“Early impacts could have been positive for early life in a number of different ways,” said Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who also presented at the AGU meeting. “They could have delivered, for instance, key elements or molecules that were missing in the near-surface that perhaps could have been important for early life.” (MORE - missing details)
https://www.centauri-dreams.org/2023/12/...servation/
EXCERPTS: The past few decades have not been easy on planet formation theories. Concepts formed on the antiquated Copernican speculation, the commonality of star systems identical to the Solar System, have given way to the strangeness and variety uncovered by Kepler, Hubble, and the other space borne telescopes. The richness of the planetary arrangements defies easy explanation.
Penn State University researchers uncovered another oddity challenging current understanding of stellar system development. Study of the LHS 3154 system reveals a planet so massive in comparison to its star that generally accepted theories of planet formation cannot explain the existence of the planet,..
[...] In current theories, stars form from condensing large clouds of gas and dust into smaller volumes. After the star forms, the left-over gas and dust which is a much smaller fraction of the original cloud, settles into a disk around the new star. From this much smaller mass, planets will condense, completing the star system. In these theories, the star consumes the major proportion of the progenitor clouds.
The Sun, for example, contains an estimated 99.8% of the mass of the Solar System. Only 0.2% is left over for the eight planets, various moons and asteroids.
The mass ratio comparing LHS 3154b to LHS 3154 is 117 times greater than mass ratio comparing the Earth to the Sun. LHS 3154b probably is Neptune-like in composition, completes its orbit in 3.7 Earth days and, the researchers believe, is a very rare world. Typically M-dwarves host small rocky bodies rather than gas giants.
According to current theories, once the star formed, there should not have been enough mass to form a planet as large as LHS 3154b...
[...] Not all mysteries are confined to M-dwarfs. A sun-like star, an infant of 14 million years some 360 light years from Earth, hosts a gas giant six times more massive than Jupiter, that orbits the star at a distance twenty times greater than the distance separating Jupiter and the Sun. ... The large distance from YSES 2b to the star does not fit either of the two most well-known models describing large gaseous planet formation...
[...] Observations by the current generation of space-borne telescopes have upset the theories of planet formation. Hot Jupiters, worlds orbiting pulsars, odd arrangements of worlds, super Earths, and wandering worlds flung close to a star then flying back have complicated the ideas of Laplace...... (MORE - missing details)
Giant space rock made Earth’s ocean boil but also helped early life
https://www.washingtonpost.com/science/2...xsxITNCnHw
EXCERPTS: The young Earth got beat up a lot, including one day 3.26 billion years ago when a rock four times the size of Mount Everest slammed into the planet. Scientists believe that the rock, which was much bigger than the Chicxulub object that ended the reign of the dinosaurs, probably landed in the ocean, since Earth had barely begun to form continents.
The collision was so violent it boiled off the top layer of that ocean and, near the impact site, created a tsunami as high as a New York skyscraper. Molten rock rained from the sky. The atmosphere was choked with ash and dust. The planet descended into darkness.
But it wasn’t all bad.
That was the counterintuitive implication of three presentations at the American Geophysical Union’s fall meeting in San Francisco this month. The scientists, working independently, found that the bludgeoning of young Earth by giant space rocks may have primed the planet to be more congenial to life.
[...] For example, the tremendous tsunami that was probably created by the impact 3.26 billion years ago would have mixed up the water column in the global ocean and brought more iron, a key nutrient for metabolism, to shallow seas. Other nutrients would have eroded into the ocean from land masses, according to Drabon.
Nick Wogan, a scientist at NASA Ames Research Center who presented at AGU, described how early impacts would have given Earth a “hot steam atmosphere” but also might have triggered life-relevant chemistry.
“Early impacts could have been positive for early life in a number of different ways,” said Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who also presented at the AGU meeting. “They could have delivered, for instance, key elements or molecules that were missing in the near-surface that perhaps could have been important for early life.” (MORE - missing details)