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 from 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.

What are H II Regions?

Michael Anissimov
Updated Feb 13, 2024
Our promise to you
AllTheScience is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

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.

Editorial Standards

At AllTheScience, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

H II regions, also known as emission nebulae, are glowing clouds of gas and plasma up to several hundred light-years across. H II regions are named after the large amounts of ionized atomic hydrogen they contain -- in astronomical parlance, H I regions refer to neutral atomic hydrogen, H II refers to ionized atomic hydrogen, and H2 refers to molecular hydrogen, the primary form in which hydrogen takes when synthesized in labs. H II regions are well known as nebulae where star formation is taking place.

The light that H II regions emit comes from all the ionized gas within. The cause of the ionization are young, hot blue stars which emit large quantities of heat and light. H II regions are among the most fascinating targets in astronomy because of the star formation taking place in them. Unfortunately, the star formation itself is concealed from us in the form of Bok globules -- pockets of gas within H II regions so dense that they obscure their contents. Typically, a Bok globule contains gas of about 10-50 solar masses in an area one light year across. More than one star typically forms within such a globule, which is why stars are often found in clusters.

An H II region can be thought of as a nebula with a density somewhere in between that of a giant molecular cloud (which is too large and diffuse to have ionized hydrogen, thus its primary component is molecular hydrogen) and the denser Bok globules, in which actual star formation takes place. H II regions are only found in spiral galaxies, and always in the arms of the spiral. They are never found in elliptical galaxies because these galaxies are thought to have been formed as the result of galactic collisions. During galactic collisions, any preexisting H II regions are likely to be agitated and their density increased to the point where almost all of the gas forms into stars, leaving behind little else.

AllTheScience 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 is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Discussion Comments

Michael Anissimov

Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology...

Read more
AllTheScience, in your inbox

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

AllTheScience, in your inbox

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