Brown Dwarf Archives

February 21, 2022February 21, 2022 by Andy Tomaswick

Twin Brown Dwarfs Discovered, Orbiting one Another at Three Times the Distance From the Sun to Pluto

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.

September 1, 2021July 12, 2022 by Brian Koberlein

Brown Dwarfs are Probably Much More Common in the Milky Way Than Previously Believed

Brown dwarfs are too big to be planets, but not quite massive enough to be stars. Credit: NASA/JPL-Caltech

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.

April 12, 2021April 12, 2021 by Brian Koberlein

Brown Dwarfs can Spin so Fast They Almost Tear Themselves Apart

Comparing the rotation of a brown dwarf with Jupiter and Saturn. Credit: Robert Hurt (IPAC/Caltech)

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.

January 29, 2021January 29, 2021 by Andy Tomaswick

We Now Have a 3D Map of The 525 Closest Brown Dwarfs

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.

January 11, 2021January 11, 2021 by Paul M. Sutter

Astronomers see Swirling Weather on the Closest Brown Dwarf

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 — An artist's conception of a brown dwarf. Brown dwarfs are more massive than Jupiter but less massive than the smallest main sequence stars. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons

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.

November 10, 2020November 10, 2020 by Brian Koberlein

Brown dwarf discovered with a radio telescope for the first time

Artist view of a cool brown dwarf. Credit: ASTRON / Danielle Futselaar

Brown dwarfs are interesting objects. They are generally defined as bodies massive enough to trigger the fusion of deuterium or lithium in their cores (and are thus not a planet) but too small to fuse hydrogen in their cores (and therefore not a star). They are the middle children of cosmic bodies.

August 28, 2020August 27, 2020 by Paul M. Sutter

Astronomers find 100 brown dwarfs in our neighborhood

Brown dwarfs are smallish objects sitting somewhere between stars and planets, making them notoriously hard to find. But a recent citizen science project aimed at finding the elusive Planet 9 has instead revealed a treasure trove of these oddities, right next door.

May 6, 2020May 6, 2020 by Evan Gough

Astronomers Can Actually See the Clouds and Weather on Brown Dwarf 6.5 Light-Years Away

This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026, observed by NASA's Hubble and Spitzer space telescopes. Brown dwarfs are more massive and hotter than planets but lack the mass required to become stars. Image credit: NASA

Brown dwarfs are in a tough spot. Not quite a star, not quite a planet, they occupy a place between gas giants and stars. They have more mass than gas giants like Jupiter, but not enough to ignite fusion and become a star.

But astronomers still study them. How could they resist?

April 15, 2020April 15, 2020 by Evan Gough

Astronomers Measure the Wind Speed on a Brown Dwarf for the First Time. Spoiler: Insanely Fast

In some ways, brown dwarfs are nature’s stellar oddballs. A lot of stars exhibit strange behaviour at different times in their evolution. But brown dwarfs aren’t even certain that they’re stars at all.

But that doesn’t mean astronomers don’t want to study and understand them.

October 10, 2018 by Evan Gough

348 Years Ago, a French Astronomer Monk Might have Witnessed the Collision Between a White and Brown Dwarf Star

This hourglass-shaped figure is named CK Vulpeculae. It was discovered by French Monk-Astronomer Per Dom Anthelme in 1670. A new study identifies it as the remnant of a collision between a white dwarf and a brown dwarf. Image Credit: ALMA (ESO/NAOJ/NRAO)/S. P. S. Eyres

There’s something poignant and haunting about ancient astronomers documenting things in the sky whose nature they could only guess at. It’s true in the case of Père Dom Anthelme, who in 1670 saw a star suddenly burst into view near the head of the constellation Cygnus, the Swan. The object was visible with the naked eye for two years, as it flared in the sky repeatedly. Then it went dark. We call that object CK Vulpeculae.

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