Characteristics of Extremely Fast Rotating Brown Dwarfs

Are Brown Dwarfs the In-Betweeners of the Cosmos?

You’ve probably heard of stars and planets, but what about brown dwarfs? These mysterious objects are more massive than most planets, but not quite heavy enough to ignite like stars. They’re the in-betweeners of the cosmos, and scientists have just discovered three of the fastest-spinning brown dwarfs ever found.

What are Brown Dwarfs?

Brown dwarfs are often referred to as “failed stars” because they don’t have enough mass to sustain nuclear fusion reactions in their cores. They’re born from the same molecular clouds as stars, but they don’t have enough gravity to collapse into a ball of hot, glowing gas. Instead, they contract and cool, eventually becoming the objects we observe today.

Characteristics of Brown Dwarfs

Brown dwarfs have some fascinating characteristics that set them apart from stars and planets. For one, they’re incredibly dense, with some having densities that are hundreds of times greater than that of water. They’re also very cool, with surface temperatures that can range from a few hundred to a few thousand degrees Celsius. And, as we’ll see, some of them can spin incredibly fast.

The Fastest-Spinning Brown Dwarfs

Scientists have just identified three brown dwarfs that spin faster than any others known. These objects are all about the same diameter as Jupiter, but they’re between 40 and 70 times more massive. They each rotate about once per hour, while the next-fastest known brown dwarfs rotate about once every 1.4 hours. That’s incredibly fast, especially when you consider that the largest of the three brown dwarfs whips around at more than 60 miles per second or about 220,000 miles per hour.

How Fast Can Brown Dwarfs Spin?

The speed measurements were made using data from NASA’s Spitzer Space Telescope, which was corroborated through observations with the ground-based Gemini North and Magellan telescopes. The authors of the study think that the three fastest brown dwarfs have all reached a spin speed limit, beyond which a brown dwarf could break apart. But what determines this speed limit, and how do brown dwarfs manage to spin so fast in the first place?

The Spin Speed Limit

The maximum spin rate of any object is determined not only by its total mass but by how that mass is distributed. This means that understanding a brown dwarf’s interior structure is crucial to understanding its spin speed. Brown dwarfs tend to speed up as they age, but it’s not clear yet if similar braking mechanisms exist in brown dwarfs to stop them from destroying themselves.

The Importance of Interior Structure

Current models show that the maximum brown dwarf spin speed should be about 50% to 80% faster than the one-hour rotation period described in the new study. But these models rely on our understanding of a brown dwarf’s interior structure, which is still a topic of debate. The state of hydrogen in the core of a brown dwarf is still very enigmatic and is extremely challenging to reproduce in high-pressure physics laboratories.

The Study of Brown Dwarfs

The study of brown dwarfs is an active area of research, with scientists using a variety of techniques to study these mysterious objects. By studying brown dwarfs, scientists can gain insights into the formation and evolution of stars and planets, as well as the possibility of life beyond Earth.

Detection Methods

Scientists use a variety of methods to detect brown dwarfs, including transit observation, radial velocity, direct imaging, and microlensing. Each of these methods reveals different clues about a brown dwarf’s size, orbit, and potential environment. For example, transit observation involves measuring the decrease in brightness of a star as a brown dwarf passes in front of it, while direct imaging involves capturing images of the brown dwarf itself.

Planetary Classification

Brown dwarfs are just one type of exoplanet, and scientists use a variety of categories to classify these objects. Gas giants, ice giants, super-Earths, and rocky terrestrial worlds are just a few examples of the different types of exoplanets that exist. Each of these categories affects what scientists can infer about internal structure, atmosphere, and possible conditions for life.

Habitability and Brown Dwarfs

While brown dwarfs are unlikely to host life themselves, they can provide insights into the possibility of life on other planets. By studying the conditions necessary for life to exist, scientists can better understand the potential for life on other planets. For example, the habitable zone, sometimes known as the “Goldilocks” zone, is the region around a star where conditions are neither too hot nor too cold for liquid water to exist.

The Goldilocks Zone

A star’s characteristics, such as size, age, and brightness, shift the boundaries of the habitable zone. Planetary features, including atmospheric composition, magnetic fields, tectonic activity, and gravitational interactions with neighboring bodies, also play a crucial role in determining habitability. By studying brown dwarfs and other exoplanets, scientists can gain insights into the possibility of life beyond Earth.

Conclusion

The study of brown dwarfs is an exciting area of research that can provide insights into the formation and evolution of stars and planets. By studying these mysterious objects, scientists can gain a better understanding of the possibility of life beyond Earth. The discovery of the fastest-spinning brown dwarfs is just one example of the many fascinating discoveries that are being made in this field. As scientists continue to study brown dwarfs and other exoplanets, we may uncover even more secrets about the universe and our place within it.