"Gliese 229B was considered the poster-child brown dwarf, and now we know we were wrong all along about the nature of the object. It's not o
A well-studied cosmic object has stunned astronomers. The "failed star" Gliese 229B has been revealed to be two so-called "brown dwarfs" that are closely orbiting each other rather than just one.
The revelation means that Gliese 229B is a "first-of-its-kind" tight brown dwarf binary, increasing the hope other such exotic systems dwell in the Milky Way just waiting to be discovered. The finding also solves a long-standing mystery about Gliese 229B, explaining why this brown dwarf appears too dim for its mass.
"Gliese 229B was considered the poster-child brown dwarf," team member and California Institute of Technology (Caltech) researcher Jerry W. Xuan said in a statement. "And now we know we were wrong all along about the nature of the object. It's not one but two. We just weren't able to probe separations this close until now."
Research alert! Rebecca Oppenheimer, a curator in the Museum’s Department of Astrophysics, co-discovered the first brown dwarf, Gliese 229B, in 1995. Since then, there’s been a long-standing mystery: Why does this brown dwarf shine so faintly despite having a significant mass—70 times that of Jupiter?
The answer, which is detailed in her latest study with Caltech—out today in the journal Nature—is that this brown dwarf is actually two objects, orbiting very closely around each other.
“These two worlds whipping around each other are actually smaller in radius than Jupiter. They’d look quite strange in our night sky if we had something like them in our own solar system,” Oppenheimer said. The discovery leads to new questions about how tight-knit brown dwarf duos like this one form and suggests that similar systems are likely out there. Read more.
A bizarre object discovered by the James Webb Space Telescope may be a pair of 'rogue' planets ― but a new study finds they are emitting rad
Lead study Mexican author Luis Rodríguez, a professor emeritus at the Institute of Radio Astronomy and Astrophysics at the National Autonomous University of Mexico
In 2023, the James Webb Space Telescope (JWST) helped identify hundreds of free-floating "rogue" planets that don't orbit a parent star. Now, astronomers have found that a pair of these planets may be producing enigmatic, hard-to-interpret radio signals.
The rogue planets spotted by JWST lie in the Orion Nebula, a long-time observational hotspot for astronomers. In total, they number over 500. This discovery bonanza was possible thanks to JWST's ability to pick up infrared radiation emitted by these relatively young planets.
Bizarrely, though, about 80 of these planets exist as pairs. Similar in mass to Jupiter, the planets orbit each other at distances ranging from 25 to 400 times the distance between Earth and the sun. These tangoing duos, called Jupiter-mass binary objects (JuMBOs), pose a huge mystery for astronomers, because the existence of these worlds challenges current theories of planet formation. Some scientists think these objects may not even be planets but rather previously unknown entities that are larger than planets but smaller than brown dwarfs, which are sometimes called "failed stars" because they blur the line between planets and stars.
The JWST data showed that JuMBOs generated infrared radiation, but the new study's authors wanted to see if these dancing objects produced radio waves. That's because different classes of cosmic objects produce distinct patterns of radio emissions. For instance, planets like Jupiter spew several types of radio signals, including gigahertz-frequency emissions thousands of times higher-pitched than an FM signal, partly because of their magnetic fields.
Spotting such signatures from the JuMBOs could help resolve their identity. The observations could also explain "why some objects have detectable radio emission and others do not," lead study author Luis Rodríguez, a professor emeritus at the Institute of Radio Astronomy and Astrophysics at the National Autonomous University of Mexico, told Live Science in an email.
To find radio wave "snapshots" of the Orion Nebula where the JuMBOs reside, the scientists combed through archives of observations maintained by the U.S. National Radio Astronomy Observatory (NRAO). They found just one pair that apparently emits radio waves: JuMBO 24. Itself an oddity among the oddball objects, it's the heaviest of the JuMBOs, and also the one with the tightest space between its component planets.
A decade's worth of data the research team collated showed that the radio waves remained steady but strong, with a power of roughly a quarter of a ton of TNT and frequencies of 6 to 10 gigahertz. The radio waves also weren't circularly polarized, meaning they lacked spiral, twisting electric fields, the team reported in their study, published Jan. 8 in The Astrophysical Journal Letters.
But these features aren't what astronomers expect of signals created by planets." Circular polarization is an unambiguous indicator of the presence of magnetic fields," Rodríguez said. Without this, the team can't say definitively that the signals come from JuMBO 24 (assuming the planets have magnetic fields). Besides, radio emissions from other exoplanets are more variable and less intense.
Even if JuMBO 24 isn't a pair of planets but rather another type of cosmic duo, the signals are unusual. Signals from brown dwarfs are very different from the newly identified radio beams. The beams' brightness and frequency even ruled out the possibility of pulsars, the rapidly spinning cores of dead stars that produce pulses of radio waves at regular intervals.
The researchers also estimated the likelihood that the signals originate from an object behind JuMBO 24 and found it to be exceedingly slim, at just 1 in 10,000. And, in case you were wondering, the signals probably don't originate from aliens. "The fact that both components emit at similar levels favors a natural mechanism," Rodríguez said.
With the research at an impasse, the team is applying to the NRAO's Very Large Array in New Mexico to collect data from free-floating planets. Until then, the radio signals will remain a mystery.
Jupiter-mass binary objects floating freely in Orion Nebula appear to defy usual definition of planets
"Dozens of planet-sized objects have been discovered in the Orion Nebula via observations that could herald the existence of a new astronomical category.
The free-floating entities, which have been named Jupiter-mass binary objects, or Jumbos, appear in spectacular images taken by the James Webb space telescope...
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Prof Mark McCaughrean, a senior adviser for science and exploration at the European Space Agency (ESA), said the observations were inspired after data from ground-based telescopes hinted at the existence of the mysterious class of object.
“We were looking for these very small objects and we find them. We find them down as small as one Jupiter mass, even half a Jupiter mass, floating freely, not attached to a star,” he said...
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The smallest stars are about 80 Jupiter masses, below which the core is not dense enough to fuse hydrogen, but smaller objects can coalesce through the same process, including dimly glowing brown dwarfs – sometimes called failed stars – and, below about 13 Jupiter masses, planetary-mass objects. But theoretical predications suggest that the lower boundary for an object forming through a star-like gravitational collapse is about three to seven Jupiter masses.
Smaller free-ranging objects have occasionally been sighted, but it was unclear whether they had formed in situ or had been ejected from a planetary disc around another star. The latest observations are more challenging to explain because, out of the hundreds of roughly Jupiter-sized objects found, dozens are in binary pairs."
More in linked article.
I wonder how many small brown dwarfs(?) like this are drifting around in interstellar space in our galaxy? Intriguing to think that if they're common there might be one relatively close to our solar system...
