Explanations 
Textbooks 
Exams 
GCSE 
IGCSE 
AS 
A Level 
International A Level 
University Admissions Tests 
Flashcards 
Vaia AI 
Notes 
Study Plans 
Study Sets 
Find a job 
Find a degree 
Student Deals 
Magazine 
Mobile App Chapter 20: Problem 16
Which of the following galaxy types has a spherical bulge and a well-defined disk? a. spiral b. barred spiral c. elliptical d. irregular
Short Answer
Expert verified
a. spiral
Step by step solution
01
Understand the Characteristics of Each Galaxy Type
There are four primary types of galaxies: spiral, barred spiral, elliptical, and irregular. Each type has distinct features regarding shape, structure, and components.
02
Characteristics of a Spiral Galaxy
Spiral galaxies have a well-defined disk structure that contains arms, and they often possess a prominent central bulge that can be spherical in shape.
03
Characteristics of a Barred Spiral Galaxy
Barred spiral galaxies are similar to spiral galaxies but have an additional feature—a central bar structure that stretches across the bulge. The arms of the galaxy extend from the ends of the bar.
04
Characteristics of an Elliptical Galaxy
Elliptical galaxies do not have a well-defined disk or arms. Their shape is more of an ellipsoid or a sphere, and they generally lack the distinct structure seen in spiral galaxies.
05
Characteristics of an Irregular Galaxy
Irregular galaxies do not have a regular shape or a well-defined disk. Their appearance is often chaotic without any prominent spherical bulge.
06
Determine the Correct Answer
From the characteristics outlined, both spiral and barred spiral galaxies have a spherical bulge and a well-defined disk. However, since the question is more broadly interpreted, it typically refers to the general classification of 'spiral' galaxies.
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.
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.
Spiral Galaxies
Spiral galaxies are fascinating structures found throughout the universe. They are characterized by their disk-shaped structure which includes arms that spiral outward. The center of a spiral galaxy often features a bright, spherical bulge filled with older stars. These arms, rich in gas, dust, and younger stars, host ongoing star formation. Spiral galaxies can be broadly classified into several subtypes based on how tightly the arms are wound.
Key points about spiral galaxies include:
Key points about spiral galaxies include:
- A distinct, disk-shaped structure.
- Spiral arms extending from the center.
- A prominent central bulge composed of older stars.
- Active regions of star formation within the arms.
Barred Spiral Galaxies
Barred spiral galaxies share many features with regular spiral galaxies, but they have a significant difference - the presence of a central bar structure. This bar runs through the central bulge and extends out into the disk, from which the spiral arms begin. Researchers believe that the bar structure influences the motion and distribution of stars and interstellar matter within these galaxies.
Key characteristics of barred spiral galaxies include:
Key characteristics of barred spiral galaxies include:
- A central bar that crosses through the bulge.
- Spiral arms that emerge from the ends of the bar.
- Active star formation occurring in the arms and sometimes along the bar.
- A mix of old stars in the bulge and younger stars in the disk.
Elliptical Galaxies
Elliptical galaxies differ significantly from spiral and barred spiral galaxies. They possess a more rounded, ellipsoidal shape without a prominent disk or spiral arms. These galaxies contain older stars and very little interstellar gas and dust, which means new star formation is minimal. Elliptical galaxies vary widely in size, from giant ellipticals containing trillions of stars to dwarf ellipticals with far fewer.
Notable features of elliptical galaxies include:
Notable features of elliptical galaxies include:
- A smooth, rounded shape.
- Lack of a disk structure and spiral arms.
- Older stellar populations with little ongoing star formation.
- Minimal gas and dust content.
Irregular Galaxies
Irregular galaxies stand out due to their lack of a regular shape, as the name suggests. They do not have a well-defined disk, spiral arms, or central bulge. Instead, their appearance is chaotic, often due to gravitational interactions with other galaxies. Irregular galaxies are rich in gas and dust, which leads to active regions of star formation. They are generally smaller than spiral and elliptical galaxies.
Key characteristics of irregular galaxies include:
Key characteristics of irregular galaxies include:
- No definitive shape or structure.
- Chaotic appearance, often due to gravitational interactions.
- Abundant gas and dust, leading to intense star formation.
- Typically smaller in size compared to other types of galaxies.
