Space and astronomy news
Nuclear fusion is what separates stars from planets. Stars are massive enough to fuse hydrogen in their cores, while planets are not. But in between these two categories are brown dwarfs, which are massive enough to experience some nuclear fusion, just not hydrogen. The largest of them are hot and star-like. The smallest of them are barely warm enough to bake a pizza.
Continue reading “Your Oven Gets Hotter Than This Star”
In 1958, the first satellites launched by the United States (Explorer 1 and 3) detected a massive radiation belt around planet Earth. This confirmed something that many scientists suspected before the Space Age began: that energetic particles emanating from the Sun (solar wind) were captured and held around the planet by Earth’s magnetosphere. This region was named the Van Allen Belt in honor of University of Iowa professor James Van Allen who led the research effort. As robotic missions explored more of the Solar System, scientists discovered similar radiation belts around Jupiter, Saturn, Uranus, and Neptune.
Given the boom in extrasolar planet research, scientists have eagerly awaited the day when a Van Allen Belt would be discovered around an exoplanet. Thanks to a team of astronomers led by the University of California, Santa Cruz (UCSC) and the National Radio Astronomy Observatory (NRAO), that day may have arrived! Using the global High Sensitivity Array (HSA), the team obtained images of persistent, intense radio emissions from an ultracool dwarf star. These revealed the presence of a cloud of high-energy particles forming a massive radiation belt similar to what scientists have observed around Jupiter.
Continue reading “An Astronomical First! A Radiation Belt Seen Outside the Solar System”
The Universe is over 13 billion years old, so a 12-year slice of that time might seem uneventful. But a timelapse movie from NASA shows how much can change in just over a decade. Stars pulse, asteroids follow their trajectories, and distant black holes flare as they pull gas and dust toward themselves.
Continue reading “NASA Provides a Timelapse Movie Showing How the Universe Changed Over 12 Years”![An artist's conception of a brown dwarf. A new study identifies CK Vulpeculae as the remnant of a collison between a brown dwarf and a white dwarf. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons](https://www.universetoday.com/wp-content/uploads/2018/10/Artist’s_conception_of_a_brown_dwarf_like_2MASSJ22282889-431026-2000x1200.jpg)
In its first few months of operation, the James Webb Space Telescope (JWST) is already proving that it was well worth the wait! To date, it has provided astronomers with the most detailed and precise images of the cosmos, conducted observations of iconic galaxies and nebulae, peered to the very edge of the Universe, and obtained spectra from distant exoplanets. These resulting images, made public through the JWST Early Release Science (ERS) program, have provided a good cross-section of what this next-generation observatory can do.
Among its many objectives, the JWST will provide valuable insights into the formation and evolution of exoplanet systems through direct imaging. Using data from the ERS, an international team of astronomers and astrophysicists conducted a direct imaging study of a brown dwarf companion (VHS 1256-1257 b) orbiting within a triple brown dwarf system approximately 69.0 light-years away. The spectra they obtained from this body provided a detailed composition of its atmosphere, which included an unexpected find – clouds made of silicate minerals (aka. sand)!
Continue reading “Webb Scans a Nearby Brown Dwarf and Finds it has Clouds Made of Sand”
Astronomers have a brown dwarf problem. They should be seeing a lot more of these objects, which are cooler than stars but hotter than planets. Yet, there have only been about 40 directly imaged over the past few decades. Why aren’t astronomers finding more of them? It helps to remember that brown dwarfs are dim, low-temperature objects. They don’t stand out in a crowded starfield. If they’re too close to their stars, the starlight hides them from our view. They’re much better observed in the infrared part of the electromagnetic spectrum. All these characteristics make hunting for them difficult.
Continue reading “A New Technique Finds a Bundle of Brown Dwarfs”
Gravity is a funny force. The gravity of every given object technically impacts every other given object, though, in practice, large distance and small masses make those forces negligible for such interactions. But in some cases, especially when large groups are floating in empty space, gravity can still hold sway over considerable distances. Such is the case with a new pair of brown dwarfs found by astronomers at the Keck Observatory.
Continue reading “Twin Brown Dwarfs Discovered, Orbiting one Another at Three Times the Distance From the Sun to Pluto”
Brown dwarfs are strange things. They are in the middle ground between planets and stars. A star is defined as an object massive enough for hydrogen to fuse into helium into its core, while a planet is too small for core fusion to occur. It seems a simple distinction until you learn about fusion. Anything with a mass below about 13 Jupiters is too small for fusion to occur, and is thus a planet. If your mass is about about 80 Jupiters, then you can fuse helium and are therefore a star. But if your mass is between 13 and 80 Jupiters, things get interesting. You can’t fuse hydrogen to shine brightly, but you can fuse lithium into other elements. This is known as lithium burning. It doesn’t provide lots of energy, but it is technically nuclear fusion.
Continue reading “Brown Dwarfs are Probably Much More Common in the Milky Way Than Previously Believed”
We tend to image planets as spheres. Held together by gravity, the material of a planet compresses and shifts until gravity and pressure reach a balance point known as hydrostatic equilibrium. Hydrostatic equilibrium is one of the defining characteristics of a planet. If a planet were stationary and of uniform density, then at equilibrium, it would be a perfect sphere. But planets rotate, and so even the largest planets aren’t a perfect sphere.
Continue reading “Brown Dwarfs can Spin so Fast They Almost Tear Themselves Apart”
Zooniverse brings out the best of the internet – it leverages the skills of average people to perform scientific feats that would be impossible otherwise. One of the tasks that a Zooniverse project called Backyard Worlds: Planet 9 has been working on has now resulted in a paper cataloguing 525 brown dwarfs, including 38 never before documented ones.
Continue reading “We Now Have a 3D Map of The 525 Closest Brown Dwarfs”
Brown dwarfs are the weird not-planets but not-stars in the universe, and astronomers have wondered for decades if their atmospheres are striped like Jupiter’s, or splotchy like the sun’s. A team of astronomers based at the University of Arizona used NASA’s TESS Observatory to find the answer: if you saw a brown dwarf for yourself, it would look more like a giant planet than a star.
Continue reading “Astronomers see Swirling Weather on the Closest Brown Dwarf”