Dust Particles in Interstellar Space

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Questions and Answers

What was the solar system composed of at the end of the first stage of planet formation?

Gas and small rocks

Hydrogen and helium gas and millions of planetesimals (correct)

Large planets and asteroids

Only gas and dust

What caused the growth rate of planetesimals to increase?

They started to emit heat

They started to orbit faster

Their gravity became strong enough to sweep up material (correct)

Their gravity became weaker

What was the result of gravitational forces between planetesimals?

They became smaller

They attracted each other and collided (correct)

They repelled each other

They started to spin faster

What happened to the planetesimal material as the protoplanets grew?

It was swept up into a few large protoplanets Signup and view all the answers

What was the result of high-speed collisions between planetesimals and protoplanets?

Fragmentation and sweeping up of small objects Signup and view all the answers

What became of the small fragments that escaped capture by a planet or moon?

They became asteroids and comets Signup and view all the answers

What was the state of the solar system after about 100 million years?

There were nine protoplanets, dozens of protomoons, and a glowing protosun Signup and view all the answers

How long did it take for the system to be cleared of interplanetary trash?

A billion more years Signup and view all the answers

What is the typical diameter of the tiny chunks of icy and rocky matter in interstellar space?

10-5 m Signup and view all the answers

What is the primary function of dust grains in the evolution of a gas cloud?

To cool the cloud by radiating heat away Signup and view all the answers

What is the role of dust grains in the formation of planets, according to the condensation theory?

They act as condensation nuclei, allowing matter to accumulate Signup and view all the answers

What is the process by which small objects grow into larger ones through collision and sticking?

Accretion Signup and view all the answers

What is the result of dust grains cooling warm matter in a gas cloud?

The cloud collapses more easily Signup and view all the answers

What is similar to the way that dust grains act as condensation nuclei in planet formation?

The formation of raindrops in Earth's atmosphere Signup and view all the answers

What is the final stage of planet formation, according to the condensation theory?

The formation of objects a few hundred kilometers across Signup and view all the answers

What is the primary material that accumulates around dust grains in the solar nebula?

Atoms and molecules Signup and view all the answers

Study Notes

Dust Particles and Interstellar Space

Dust particles likely formed in cool atmospheres of old stars and grew by accumulating atoms and molecules from interstellar gas.
Interstellar space is filled with tiny chunks of icy and rocky matter, with typical diameters of about 10^(-5) m.

Role of Dust in Planet Formation

Dust grains play a crucial role in gas cloud evolution by efficiently radiating heat away in the form of infrared radiation, allowing the nebula to collapse more easily.
Dust grains act as condensation nuclei, providing microscopic platforms for other atoms to attach and form larger and larger balls of matter.

Planet Formation Stages

According to the condensation theory, planets formed in three stages:
- Stage 1: Dust grains formed condensation nuclei, allowing matter to accumulate and form small clumps.
- Stage 2: Clumps grew rapidly by sticking to other clumps, eventually forming objects a few hundred kilometers across.
- Stage 3: Gravity led to collisions and mergers between planetesimals, forming larger and larger objects, eventually leading to the formation of protoplanets.

Protoplanets and Planetesimal Evolution

By the end of the first stage, the solar system consisted of hydrogen and helium gas and millions of planetesimals (objects the size of small moons with sufficient gravitational fields).
During the second phase, gravitational forces between planetesimals led to collisions and mergers, forming larger and larger objects.
Protoplanets grew through accretion, eventually sweeping up almost all planetesimal material and forming the planets we know today.

Formation of Asteroids and Comets

High-speed collisions between planetesimals and protoplanets led to fragmentation, resulting in small objects that were swept up by protoplanets.
A small number of 10- to 100-km fragments escaped capture, becoming asteroids and comets.

Evolution of the Solar System

After about 100 million years, the primitive solar system had evolved into nine protoplanets, dozens of protomoons, and a glowing protosun at the center.
Computer simulations reproduce the increasing spacing between the planets, although the reasons for this regularity remain unclear.
It took roughly a billion more years to clear the system of interplanetary debris.

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Description

Learn about the formation and growth of dust particles in the cool atmospheres of old stars and their role in the evolution of gas clouds.