Brown Dwarf Archives

October 17, 2024October 17, 2024 by Matt Williams

Astronomers Solve the Mystery of the Famed Brown Dwarf That is Too Bright: It’s Twins!

This artwork highlights a pair of recently uncovered brown dwarf twins, named Gliese 229 Ba and Gliese 229 Bb. Credit: K. Miller/R. Hurt (Caltech/IPAC)

In 1995, Caltech researchers at the Institute’s Palomar Observatory first observed what appeared to be a brown dwarf orbiting Gliese 229 – a red dwarf star located about 19 light-years from Earth. Since then, this brown dwarf (Gliese 229 B) has mystified astronomers because it appeared too dim for its mass. With 70 times the mass of Jupiter, it should have been brighter than what telescopes had observed. However, a Caltech-led international team of astronomers recently solved the mystery by determining that the brown dwarf is a pair of closely orbiting twins!

August 20, 2024August 20, 2024 by Mark Thompson

Citizen Scientists Find a Star Escaping the Milky Way

This artist's concept shows a hypothetical white dwarf, left, that has exploded as a supernova. The object at right is CWISE J1249, a star or brown dwarf ejected from this system as a result of the explosion. This scenario is one explanation for where CWISE J1249 came from. W.M. Keck Observatory/Adam Makarenko

Citizen science is such a great concept. Using the combined computing power of a gazillion (exaggeration) desktop and laptops to churn through data is an excellent and efficient way of analysing volumes of data. This has been shown yet again as a star has been identified to be hurtling out to intergalactic space! Most stars in the Milky Way are not travelling fast enough to be able to escape its immense gravity but the suspected brown dwarf is travelling at 1.5 million km/h, fast enough to escape.

July 16, 2024July 16, 2024 by Mark Thompson

Webb Maps the Weather on the Closest Brown Dwarfs to Earth

An artist’s impression of the nearest brown dwarf to Earth, WISE 1049AB, (pictured main), along with an impression of the stormy weather on a brown dwarf planet (inset). Credit ESO-I. Crossfield-N. Risinger

James Webb Space Telescope (JWST) has done it again. A team of astronomers have used it to map the weather on a pair of brown dwarf stars. Infrared light was analysed from the pair and its variation over time was measured. The team were able to generate a 3D picture of the weather and discovered gasses in the atmosphere like water vapour, methane and carbon dioxide. Swirling clouds of hot sand were also found with temperatures reaching as high as 950 C!

April 29, 2024April 29, 2024 by Brian Koberlein

A Cold Brown Dwarf is Belching Methane Into Space

This artist concept portrays the brown dwarf W1935. Credit: NASA, ESA, CSA, Leah Hustak (STScI)

Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperatures around 3,000 K and look essentially like stars.

March 25, 2024March 25, 2024 by Evan Gough

Brown Dwarf Pairs Drift Apart in Old Age

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. Their dimness and low mass make them difficult to detect. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons

The only thing worse than drifting through space for an eternity is doing it alone. Observations with the Hubble Space Telescope show that brown dwarfs that once had companions suffer that fate. Binary brown dwarfs that were once bound to each other tend to drift apart as time passes.

February 24, 2024February 24, 2024 by Laurence Tognetti

Brrr. JWST Looks at the Coldest Brown Dwarf

Artist's illustration of a cold brown dwarf star. (Credit: NASA)

What are the atmospheric compositions of cold brown dwarf stars? This is what a recent study published in The Astronomical Journal hopes to address as an international team of researchers used NASA’s James Webb Space Telescope (JWST) to investigate the coldest known brown dwarf star, WISE J085510.83?071442.5 (WISE 0855). This study holds the potential to help astronomers better understand the compositions of brown dwarf stars, which are also known as “failed stars” since while they form like other stars, they fail to reach the necessary mass to produce nuclear fusion. So, what was the motivation behind using JWST to examine the coldest known brown dwarf star?

January 10, 2024January 10, 2024 by Nancy Atkinson

A Solo Brown Dwarf Found With Auroras

This artist concept portrays the brown dwarf W1935, which is located 47 light-years from Earth. Astronomers using NASA’s James Webb Space Telescope found infrared emission from methane coming from W1935, generating an aurora, a very unexpected discovery. Credit: NASA, ESA, CSA, Leah Hustak (STScI)

Astronomers have used JWST to find a brown dwarf with polar auroras like the Earth, or Jupiter. This is surprising because the brown dwarf, dubbed W1935, is a free-floating object, meaning it isn’t part of another star system. Therefore, there’s no solar wind available to generate any Northern Lights. Instead, the auroras are seemingly generated from methane emissions in the planet’s atmosphere, interacting with the interstellar plasma. Another theory is that it perhaps has an active but unseen moon contributing to the emissions.

September 11, 2023September 22, 2023 by Evan Gough

JWST Accidentally Found 21 Brown Dwarfs

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

When you launch humanity’s most powerful telescope, you expect results. The JWST has delivered excellent results by detecting ancient galaxies, identifying chemicals in exoplanet atmospheres, and peering into star-forming regions with more detail and clarity than any other telescope.

But every time a new telescope is about to enter service, astronomers tell us they’re excited not only about the expected results but also about the surprising results. And like other telescopes, the JWST has also delivered some surprises. While going about its business, the JWST has discovered 21 brown dwarfs.

August 17, 2023August 17, 2023 by Nancy Atkinson

This Brown Dwarf is 2,000 Degrees Hotter Than the Sun

exoplanet hot jupiter transiting its star — This artist’s impression shows an ultra-hot exoplanet as it is about to transit in front of its host star. Credit: ESO

Astronomers have discovered an intense binary star system located about 1,400 light years away. It contains a brown dwarf with 80 times the mass of Jupiter which is bound closely with an incredibly hot white dwarf star. Observations have shown the brown dwarf is tidally locked to the white dwarf, allowing the daytime surface temperatures on the brown dwarf to reach 8,000 Kelvin (7,700 Celsius, 14,000 Fahrenheit) — which is much hotter than the surface of the Sun, which is about 5,700 K (5,427 C, 9,800 F). The brown dwarf’s nightside, on the other hand, is about 6,000 degrees K cooler.

July 18, 2023July 18, 2023 by Brian Koberlein

Your Oven Gets Hotter Than This Star

An artist’s depiction of the relative sizes of the Sun, a low-mass star, a brown dwarf, Jupiter, and the Earth. Credit: Jupiter: NASA,ESA,and A. Simon (NASA,GSFC); Sun and Low-Mass Star: NASA,SDO; Brown Dwarf: NASA,ESA,and JPL-Caltech; Earth: NASA; Infographic: NASA and E. Wheatley (STScI)

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.