Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 7: Problem 18

What is a protoplanetary disk? What are two reasons that the inner part of the disk is hotter than the outer part?

Short Answer

Expert verified
A protoplanetary disk is a disk of gas and dust around a new star. The inner part is hotter due to proximity to the star and accretion heating.

Step by step solution

01

Understanding Protoplanetary Disks

A protoplanetary disk is a rotating circumstellar disk of dense gas and dust surrounding a newly formed star. It is the region where planets are formed.
02

Reason 1 - Proximity to the Star

The inner part of the protoplanetary disk is hotter because it is closer to the central star. The star emits significant amounts of radiation and heat, causing nearby materials to become much hotter.
03

Reason 2 - Accretion Heating

The inner parts of the disk experience more intense accretion processes. As materials spiral inward due to gravitational forces, they collide and release kinetic energy as heat, further increasing the temperature of the inner region.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Circumstellar Disk
A circumstellar disk, also known as a protoplanetary disk, surrounds a newly formed star. This disk is made of dense gas and dust, which forms a flat, rotating structure.
It is significant because it's the birthplace of planets.
The materials in the circumstellar disk come from remnants of gas and dust left over from the star formation process. Over time, these materials clump together to form larger bodies.
In essence, the circumstellar disk is crucial in understanding how planetary systems emerge and evolve.
Planet Formation
Planet formation takes place within the protoplanetary disk. This process begins with small dust particles sticking together through electrostatic forces.
As they grow in size, gravity helps clump more materials together, forming planetesimals and eventually protoplanets.
There are two main methods of planet formation:
  • Core Accretion: This is the dominant theory for forming terrestrial planets like Earth. It involves the gradual buildup of solid materials.
  • Disk Instability: This method may form gas giants quickly by the disk's gas forming dense clumps, collapsing under its gravity.
Understanding planet formation gives insights into the diversity of planetary systems observed throughout the galaxy.
Accretion Heating
Accretion heating happens when materials in a protoplanetary disk collide and stick together. This process often takes place in the disk's inner regions.
As materials spiral inward toward the star, they move faster due to gravity. These high-speed collisions release kinetic energy, turning it into heat.
This heat contributes significantly to the increased temperature of the inner disk.
Accretion heating effects can be observed because the inner parts of the disk glow brightly in certain wavelengths, indicating high energy and temperature.
Stellar Radiation
Stellar radiation refers to the energy emitted by a star in the form of light and heat. This energy has a profound effect on the protoplanetary disk.
The inner part of the disk receives more stellar radiation due to proximity to the star. As a result, the material there becomes much hotter than that in the outer regions.
Stellar radiation also influences the disk's chemistry, which can affect planet formation.
Additionally, radiation pressure from the star can push away smaller particles, helping to clear out the disk over time.
Understanding stellar radiation allows us to grasp how proto-planets can survive and evolve under different energy regimes.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The asteroid Vesta has a diameter of \(530 \mathrm{km}\) and a mass of \(2.7 \times 10^{20} \mathrm{kg}\) a. Calculate the density (mass/volume) of Vesta. b. The density of water is \(1,000 \mathrm{kg} / \mathrm{m}^{3},\) and that of rock is about \(2,500 \mathrm{kg} / \mathrm{m}^{3} .\) What does this difference tell you about the composition of this primitive body?

The best current technology can measure radial velocities of about \(0.3 \mathrm{m} / \mathrm{s}\). Suppose you are observing a spectral line with a wavelength of 575 nanometers (nm). How large a shift in wavelength would a radial velocity of \(0.3 \mathrm{m} / \mathrm{s}\) produce?

The planet COROT-11b was discovered using the transit method, and astronomers have followed up with radial velocity measurements, so both its size (radius \(1.43 R_{\text {Jup }}\) ) and its \(\operatorname{mass}\left(2.33 M_{\text {Jup }}\right)\) are known. The density provides a clue about whether the object is gaseous or rocky. a. What is the mass of this planet in kilograms? b. What is the planet's radius in meters? c. What is the planet's volume? d. What is the planet's density? How does this density compare to the density of water \(\left(1,000 \mathrm{kg} / \mathrm{m}^{3}\right) ?\) Is the planet likely to be rocky or gaseous?

A planet in the "habitable zone" a. is close to the central star. b. is far from the central star. c. is the same distance from its star as Earth is from the Sun. d. is at a distance where liquid water can exist on the surface.

Unlike the giant planets, the terrestrial planets formed when a. the inner Solar System was richer in heavy elements than the outer Solar System. b. the inner Solar System was hotter than the outer Solar System. c. the outer Solar System took up more volume than the inner Solar System, so there was more material to form planets. d. the inner Solar System was moving faster than the outer Solar System.
See all solutions

Recommended explanations on Physics Textbooks

Modern Physics

Read Explanation

Nuclear Physics

Read Explanation

Rotational Dynamics

Read Explanation

Electromagnetism

Read Explanation

Oscillations

Read Explanation

Fluids

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free