RE: LeoThread 2024-10-19 19:18

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Building blocks of life on Earth originate from a relatively small amount of source material

'It would be very inconvenient for us if we were being repeatedly blasted by supernovae.'

One of the key components for the evolution of life as we know it is the presence of “volatiles”: elements and compounds that can be vaporized easily at relatively low temperatures. This means that understanding where these volatiles came from, and whether Earth is unusually rich in them, is critical to understanding what makes life possible—and a new study, published October 11 in Science Advances, suggests that most originate in a relatively small proportion of the material from which the planet formed.

#science #technology #life

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[taskmaster4450le]

Planets form from the gradual accretion of smaller pieces of material, referred to as planetesimals. There are two basic categories of planetesimal: differentiated and undifferentiated. Both start off as what Rayssa Martins, the study’s first author, describes as “big lumps of dust and other small rocky bits (often loosely) stuck together.” Undifferentiated planetesimals basically remain this way; differentiated planetesimals, by contrast, are characterized by having been subjected to enough heat to melt all their component parts together.

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This melting is caused by the radioactive decay of aluminum-26 (Al-26), an unstable isotope of aluminum. As it decays, Al-26 generates so much heat that it essentially melts the material around it. “In this process,” explains Martins, “a lot of volatiles are degassed.” Once vaporized, the volatiles simply drift away into space: “[They are] lost due to the low gravity of these small bodies.”

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Thankfully for us, all the Al-26 in our solar system decayed away very early on, leaving enough undifferentiated material to supply the Earth with the volatile compounds it needed to evolve life. And once Al-26 is gone, it’s gone. The isotope is formed in the heart of stars that have burned through all their hydrogen and are hurtling toward their explosive final moments.

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Article

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What are planetsimals?

Let's dive deeper into the world of planetesimals.

Formation of Planetesimals

The formation of planetesimals is a complex process that involves the interaction of small particles in a solar nebula. A solar nebula is a cloud of gas and dust that surrounds a young star, and it's the raw material from which planets are formed.

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There are several mechanisms that can lead to the formation of planetesimals:

1. Accretion: accretion occurs when small particles in the solar nebula collide and merge, growing larger and more massive over time. This process continues until the particles become large enough to become planetesimals.
2. Gravitational collapse: Small particles in the solar nebula can collapse under their own gravity, forming small, solid bodies called planetesimals.
3. Fragmentation: Large particles in the solar nebula can break apart into smaller pieces, which can then grow into planetesimals.
4. Condensation: Material from the solar nebula can condense and become part of a planetesimal.

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Types of Planetesimal Formation

There are several types of planetesimal formation, including:

1. Core accretion: This is the most widely accepted model of planetesimal formation. It involves the accretion of small particles to form a solid core, which is then surrounded by a mantle of rock and metal.
2. Planetary differentiation: This model involves the differentiation of a planetesimal into its component parts, such as a core, mantle, and crust.
3. Gravitational collapse: This model involves the collapse of a large particle in the solar nebula, which can form a planetesimal.
4. Fragmentation: This model involves the break-up of a large particle in the solar nebula, which can form smaller planetesimals.

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Characteristics of Planetesimals

Planetesimals have several key characteristics that distinguish them from other types of particles:

1. Solid composition: Planetesimals are composed of solid materials, such as rock and metal, which are held together by gravity.
2. Small size: Planetesimals are typically much smaller than planets, ranging in size from a few micrometers to several kilometers in diameter.
3. High density: Planetesimals are dense, with densities that are typically higher than those of asteroids and comets.
4. Round shape: Planetesimals are often spherical in shape, reflecting their high density and gravity.

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Properties of Planetesimals

Planetesimals have several properties that are of interest to scientists:

1. Density: The density of a planetesimal can provide information about its composition and formation history.
2. Composition: The composition of a planetesimal can provide information about the early solar system and the processes that formed it.
3. Shape: The shape of a planetesimal can provide information about its rotation rate and gravitational structure.
4. Orbital characteristics: The orbital characteristics of a planetesimal, such as its semi-major axis and eccentricity, can provide information about its formation history and evolution.

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Detection and Study of Planetesimals

Detecting and studying planetesimals can be challenging due to their small size and the fact that they often reside in the outer reaches of the solar system. However, several techniques have been developed to study planetesimals, including:

1. Asteroid hunting: Astronomers use telescopes to detect and track asteroids, which are thought to be remnants of planetesimals.
2. Comet studies: Comets are thought to be icy planetesimals that have been perturbed from their orbits and are nOW traveling through the solar system.
3. Laboratory experiments: Scientists use laboratory experiments to simulate the conditions under which planetesimals form and evolve.
4. Computer simulations: Scientists use computer simulations to model the formation and evolution of planetesimals.

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Planetary Core Formation

The formation of planetary cores is a critical process in the formation of planets. Planetesimals can accrete to form cores, which are then surrounded by a mantle of rock and metal.

Core Accretion Model

The core accretion model is the most widely accepted model of planetary core formation. It involves the accretion of small particles to form a solid core, which is then surrounded by a mantle of rock and metal.

Core Differentiation

Core differentiation is the process by which a planetesimal differentiates into its component parts, such as a core, mantle, and crust.

Gravitational Collapse

Gravitational collapse is the process by which a large particle in the solar nebula collapses under its own gravity, forming a planetesimal.

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Fragmentation

Fragmentation is the process by which a large particle in the solar nebula breaks apart into smaller pieces, which can then grow into planetesimals.

Consequences of Planetesimal Formation

The formation of planetesimals has several consequences for the formation of planets:

1. Accretion of material: The formation of planetesimals leads to the accretion of material, which can form planets.
2. Differentiation of planets: The formation of planetesimals can lead to the differentiation of planets, which can result in the formation of a core, mantle, and crust.
3. Influence on planetary orbits: The formation of planetesimals can influence the orbits of planets, which can result in the formation of a stable planetary system.

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Challenges in Studying Planetesimals

Studying planetesimals can be challenging due to their small size and the fact that they often reside in the outer reaches of the solar system. However, several techniques have been developed to study planetesimals, including:

1. Asteroid hunting: Astronomers use telescopes to detect and track asteroids, which are thought to be remnants of planetesimals.
2. Comet studies: Comets are thought to be icy planetesimals that have been perturbed from their orbits and are NOW traveling through the solar system.
3. Laboratory experiments: Scientists use laboratory experiments to simulate the conditions under which planetesimals form and evolve.
4. Computer simulations: Scientists use computer simulations to model the formation and evolution of planetesimals.

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Future Research Directions

Future research directions in the field of planetesimal science include:

1. Studying the early solar system: Scientists are working to study the early solar system and the processes that formed it.
2. Investigating the formation of planetary cores: Scientists are working to investigate the formation of planetary cores and the differentiation of planets.
3. Developing new detection techniques: Scientists are working to develop new detection techniques for planetesimals, such as asteroid hunting and comet studies.
4. Modeling the evolution of planetesimals: Scientists are working to model the evolution of planetesimals and the processes that form them.

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In conclusion, planetesimals are small, solid particles that played a crucial role in the formation and evolution of planetary systems, including our own. By studying planetesimals, we can gain insights into the early history of the solar system and the formation of our planet, Earth.