We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What is a White Dwarf?

Michael Anissimov
Updated: May 21, 2024

A white dwarf is a relatively small, dense type of star that is formed when a main sequence star burns all of its hydrogen and helium fuel but lacks the pressure and heat necessary to fuse carbon and oxygen. A white dwarf has a mass typically between 0.5 and 0.7 times that of the Sun, but a volume comparable to that of the Earth. White dwarfhood is the end state of stellar evolution for 97% of known stars.

The transformation of a star into a white dwarf begins when a main sequence star, around the mass of our Sun, burns up all its hydrogen fuel and starts being forced to fuse helium into carbon and oxygen. Because its core starts to build up with carbon and oxygen that cannot be fused, the fusion must take place on a shell outside the core. The immense gravity of the core pushes the hydrogen together and causes it to fuse much faster than before, increasing the luminosity of the star by a factor of 1,000 - 10,000 and increasing its radius to something comparable to Mars' orbit.

When all the hydrogen in the star is fused, gravity takes over and the star begins to fall in on itself. If the star is sufficiently massive, a supernova may occur. Otherwise, the excess material just floats away to form a planetary nebula, and only the super-dense core remains, which is the white dwarf. Because a white dwarf have no source of energy of its own, the only heat it produces is a remnant from its helium-fusing days. After billions of years, it is predicted that white dwarfs cool to become black dwarfs, lifeless stellar husks, although the age of the universe (13.7 billion years) has not been sufficient for this to occur yet.

White dwarfs make up 6% of all stars in our solar neighborhood. Because no nuclear reactions occur in their core, they aren't very bright, although they are observable with powerful telescopes. Sirius B, the companion of its more famous partner, Sirius A, also known as the Dog Star, is a white dwarf. The first white dwarf was observed by Friedrich Herschel on 31 January 1783, in a binary system, Eridani B and C.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology, astronomy, chemistry, and futurism to his articles. An avid blogger, Michael is deeply passionate about stem cell research, regenerative medicine, and life extension therapies. His professional experience includes work with the Methuselah Foundation, Singularity Institute for Artificial Intelligence, and Lifeboat Foundation, further showcasing his commitment to scientific advancement.
Discussion Comments
By wizup — On Jun 27, 2011

@goldensky - White dwarfs are not big enough to explode into a supernova. Normally they will expand similar to our sun and then shrink into a white dwarf and then go black.

They are dead stars and there isn't sufficient enough mass for a white dwarf to go supernova, however the giant stars do possess enough mass to create an explosion.

The only way it could harm the Earth is if it's pole's were directed right at us. The event of this happening is very unlikely though.

A supernova that occurs less than one hundred light years away would definitely destroy the Earths ozone layer exposing everything to cosmic radiation. Every species would be affected by extinction and horrific environmental changes.

By goldensky — On Jun 25, 2011

Is it possible for a white dwarf star to turn supernova? If it were say only about eight light years away, how long would we have to protect ourselves from it's radiation?

By anon14152 — On Jun 11, 2008

This web site really helped me out. It had every thing i needed to finish my project. Thanks a lot to everyone that helped make it, and your doing a great job! Hope to come back soon.

By anon11459 — On Apr 16, 2008

wisegeek, your web site is the best thanks for the info.

Michael Anissimov
Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology...
Learn more
All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.