This holiday season, scientists received an unexpected “gift” in the form of a groundbreaking theory that may unravel the mystery of JuMBOs, or Jupiter-mass binary objects. These celestial bodies, neither planets nor stars, have perplexed astronomers since their discovery in 2023. Now, a team of researchers has proposed that JuMBOs are actually stellar cores stripped of their outer layers by the powerful radiation of massive stars.
Enigma of JuMBOs
JuMBOs came into focus when astronomers, using the James Webb Space Telescope (JWST), detected 42 pairs of free-floating planetary-mass objects in the Orion Nebula Cluster. These pairs were unusual: they weren’t tethered to a star and maintained a binary configuration, defying traditional formation mechanisms for planets or stars.
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Typically, planets form in circumstellar disks around stars, and stars form from dense patches in gas clouds. But JuMBOs didn’t fit neatly into either category. Their binary nature further deepened the mystery, as the forces required to eject planetary pairs from a star would likely disrupt their binary structure. With 42 pairs found in one nebula, this was no anomaly.
A New Perspective: Stellar Cores “Unwrapped”
Led by Richard Parker of the University of Sheffield and undergraduate student Jessica Diamond, the research team revisited a 20-year-old concept of “photo erosion” to explain JuMBOs. In this process, massive stars emit intense radiation that strips away the outer layers of nearby stellar cores. This results in objects with planetary masses but binary structures, explaining why JuMBOs resemble a hybrid of stars and planets. “We are using quite an old idea,” Parker told Space.com. “Radiation from massive stars is so strong it erodes the gas ‘core’ that eventually forms a star.”
This idea aligns with the dense, radiation-heavy environment of the Orion Nebula, which is rich in massive OB-type stars. The theory posits that JuMBOs were born as binary stars but were sculpted into their current form by the relentless radiation.
Implications for Astronomy
This theory offers a significant shift in understanding star and planet formation. If correct, it negates the need for JuMBOs to form like planets or as unconventional brown dwarf binaries. Brown dwarfs, often called “failed stars,” form similarly to stars but lack sufficient mass to sustain hydrogen fusion. JuMBOs, according to Parker, are more akin to stars that were reshaped by environmental factors.
Astronomers now face the challenge of verifying this theory. By studying other star-forming regions with massive stars, they can test if JuMBOs are consistently less massive in high-radiation environments or absent where radiation is weak.
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Parker emphasized the urgency of studying JuMBOs in Orion. The crowded nebula environment may disrupt these pairs, making them transient phenomena. Yet, he remains optimistic, believing that similar objects could emerge in other regions. “My mantra is ‘never expect anything and keep an open mind at all times,'” Parker remarked.