Copyright

Red Supergiant: Definition, Facts & Life Cycle

Red Supergiant: Definition, Facts & Life Cycle
Coming up next: Stars: Definition & Facts

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:01 Definition of a Supergiant
  • 1:00 Gravity and Nuclear…
  • 2:05 Day in the Life of a…
  • 2:54 Death of Supergiants
  • 3:38 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Katie Chamberlain

Katie has a PhD in Microbiology and has experience preparing online education content in Biology and Earth Science.

This lesson defines red supergiants and provides some interesting facts and life cycle information. Check your knowledge with a quiz that follows the lesson.

What Does It Take to Be a Supergiant?

A red supergiant is an aging giant star that has consumed its core's supply of hydrogen fuel. Helium has accumulated in the core, and hydrogen is now undergoing nuclear fusion in the outer shells. These shells then expand, and the now cooler star takes on a red color. They are the largest known stars.

As stars age, they go through various phases of their lives. These phases are so diverse that it is hard to believe that they are all just the same star (much like an infant, a teenager, and an elderly human seem quite different). At various points in a star's life, different things will happen depending on the size of the star. Only large stars with a mass of about ten solar units will go on to become red supergiants. The famous star, Betelgeuse, is a red supergiant star in the constellation Orion.

Gravity and Nuclear Fusion in Stars

The Hollywood lifestyle might look luxurious, but it is difficult to be a star. There are a number of forces at work at all times just to keep them twinkling: gravity is pushing inwards, and the energy released from nuclear fusion is pushing outwards. All stars begin as main sequence stars, fusing hydrogen into helium within their core. As this hydrogen depletes, however, so does the energy pushing outwards. Gravity is then the dominant force, and the outer layers contract inwards.

This contraction increases the pressure inside the star, and it causes hydrogen to fuse in the outer shell layers (where it has not yet been depleted). This new source of energy counteracts gravity, and the layers expand outwards creating a supergiant star. Since these large outer layers burn cooler than the core (3,500-4,500 K), the star appears red. VX Sagittarii is an example of a lovely red supergiant star.

A Day in the Life of a Supergiant

Apart from increasing in size and changing color, red supergiant stars kick off the fusion in their cores again. The helium that accumulated during their main sequence phase begins to fuse into carbon. When the pressure gets high enough, the carbon will fuse into oxygen, and these changes will continue as heavier and heavier elements are fused.

As the different types of fusion occur, the red supergiant will swell and contract, thus making it variable in size. In general, however, red supergiants have radii approximately 1,500 times larger than the radius of our sun. The largest of the supergiants are called hypergiants. The largest such hypergiant is VY Canis Majoris, which has a radius 1800 times larger than our sun's.

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create An Account
Support