Recent images from the James Webb Space Telescope have unveiled intriguing pairs of planet-like objects in the Orion Nebula that defy previous detection. The Orion Nebula, a luminous cloud of dust and gas, is among the most prominent nebulae in the night sky and is recognizable as the “sword” in the Orion constellation. Situated 1,300 light-years from Earth, this nebula has been a focal point for astronomers, offering a plethora of celestial objects to investigate, including planet-forming disks encircling young stars and brown dwarfs, which are celestial bodies with mass falling between that of planets and stars.
Astronomers employed Webb’s near-infrared camera, known as NIRCam, to capture comprehensive images of the Orion Nebula, spanning both short and long wavelengths of light, thereby unveiling unprecedented insights and unforeseen revelations.
In their examination of the short-wavelength image of the Orion Nebula, astronomers Samuel G. Pearson and Mark J. McCaughrean directed their attention to the Trapezium Cluster, a youthful star-forming region approximately one million years old, teeming with thousands of emerging stars. Among these stars, the scientists identified brown dwarfs, celestial objects too small to initiate the nuclear fusion process characteristic of stars. Brown dwarfs possess a mass less than 7% that of the Sun.
While on the quest to locate additional low-mass isolated entities, the astronomers stumbled upon an entirely novel phenomenon: pairs of planet-like objects with masses ranging from 0.6 to 13 times that of Jupiter. These enigmatic objects appeared to challenge some fundamental tenets of astronomical theories, prompting the scientists to christen them “Jupiter Mass Binary Objects,” or JuMBOs.
Although some of these JuMBOs exceed the mass of Jupiter, they are generally comparable in size, only slightly larger. According to Pearson, a European Space Agency research fellow based at the European Space Research and Technology Centre in the Netherlands, “Although some of them are more massive than the planet Jupiter, they will be roughly the same size and only slightly larger.”
The astronomers’ investigation unveiled a total of 40 pairs of JuMBOs and two triple systems, all of which exhibited wide orbits around one another. Despite their paired existence, these objects typically maintained a separation of about 200 astronomical units, equivalent to 200 times the distance between Earth and the Sun. Completing an orbit around each other required a substantial duration, ranging from 20,000 to 80,000 years.
These enigmatic JuMBOs exhibited a temperature range spanning from 1,000 degrees Fahrenheit (537 degrees Celsius) to 2,300 degrees Fahrenheit (1,260 degrees Celsius). These gaseous entities are relatively youthful in astronomical terms, boasting an age of approximately one million years, whereas our solar system has endured for 4.57 billion years
Mark J. McCaughrean, senior adviser for science and exploration at the European Space Agency, aptly characterized these objects as “3-day-old babies” compared to the age of our solar system. Their continued luminosity and warmth stem from the energy they retained at their formation, allowing them to emit detectable light.
To document their discoveries in the Orion Nebula, McCaughrean and Pearson composed two research papers, which have been submitted for publication in academic journals. Preliminary findings are available on the preprint platform arXiv. However, numerous questions about JuMBOs persist, particularly regarding their origins.
The formation of stars typically originates from massive clouds of gas and dust that succumb to gravitational forces, a process accompanied by the emergence of planetary systems. Nevertheless, existing theories fail to account for the formation of JuMBOs or their presence in the Orion Nebula, as McCaughrean noted. While some might liken JuMBOs to rogue planets, objects of planetary mass that roam through space independently of stars, it remains challenging to explain how pairs of these objects were simultaneously expelled while maintaining gravitational connection.
Pearson emphasized the implications of these discoveries, stating, “Scientists have been working on theories and models of star and planet formation for decades, but none of them have ever predicted that we would find pairs of super low mass objects floating alone in space — and we’re seeing lots of them.” This revelation raises questions about the understanding of both planet and star formation.
The Orion Nebula ranks among astronomers’ favored targets for observation. As telescopes grow in size and sophistication, they reveal an increasing number of objects within this nebula. Pearson underscored the significance of Webb’s infrared capabilities, stating, “JWST is the most powerful infrared telescope that has ever been built, and these observations simply wouldn’t be possible with any other telescope.”
Future observations scheduled for early 2024 may provide further insights into the atmospheric compositions of JuMBOs. Researchers also seek to refine their understanding of these objects by obtaining precise measurements of their masses. Furthermore, investigations focused on other star-forming regions could determine whether JuMBOs are present beyond the confines of the Orion Nebula.
As Pearson summarized, “The main question is, ‘What?! Where did that come from?’ It’s just so unexpected that a lot of future observations and modeling are going to be needed to explain it.”