A research team using the James Webb Space Telescope (JWST) discovered the smallest free-floating brown dwarf ever recorded, as well as two other “failed stars.” They are located in a star cluster just 1,000 light-years from Earth and are not associated with a parent star. It was discovered that Posted on December 13th astronomy magazine This could help astronomers better determine boundaries between stars and planets.
[Related: A Jupiter-sized dwarf star burns half as hot as a campfire.]
failed star
brown dwarf A celestial body that is more massive than a planet but not as large as a star. They form like stars, becoming dense enough to collapse under their own gravity, but never dense enough and hot enough to begin the fusion of hydrogen needed to become a star. Therefore, they are nicknamed “Failed Stars”.
of brown dwarf JWST The speck has about eight times the mass of Jupiter. The smallest of these stars, on the other hand, has about three times the mass of Jupiter. current theory About how this kind of celestial body is formed. Astronomers are using his JWST to try to determine what the smallest celestial bodies that can form star-like shapes are.
“One of the fundamental questions you’ll find in any astronomy textbook is: What is the smallest star? That’s what we’re trying to answer,” said study co-author and Penn State University professor. says astronomer Kevin Luman of stated in a statement.
clean the sky
Luman and his colleague Catalina Alves de Oliveira began their search as follows: Star cluster IC 348. This group is located only about 1,000 light-years away within the Perseus star-forming region. Star cluster IC 348 is relatively young. Only about 5 million years ago. Because of their age, any brown dwarfs that do exist will still be relatively bright in the infrared, glowing from the heat of their formation.
They used JWST to image the center of the cluster. near infrared camera (NIRCam) to identify brown dwarf candidates based on brightness and color. Next, they used the telescope’s microshutter array. near infrared spectrometer (NIRSpec) to find the most promising targets. JWST’s high sensitivity to infrared light allowed the team to detect fainter objects than other ground-based telescopes.
They narrowed down the star cluster to Three possible targets. All stars weighed between 3 and 8 times the mass of Jupiter and had surface temperatures ranging from 1,500 degrees Fahrenheit to 2,800 degrees Fahrenheit. The team’s computer model suggests that the smallest target would be only three to four times the size of Jupiter, which could provide clues to how stars form.
[Related: Two tiny stars fit into an orbit smaller than our sun.]
“With current models, it would be very easy to create a giant planet in a disk around a star,” said study co-author Catarina Alves de Oliveira, an astronomer at the European Space Agency (ESA). stated in a statement. “But in this cluster, the objects are unlikely to form in a disk shape, instead forming like stars, with the three Jupiters having 1/300th the mass of the Sun. We have to ask how the star formation process takes place at such a very small mass.”
strange molecules
Small brown dwarfs can also help astronomers better understand exoplanets, as the smallest brown dwarfs overlap with the largest known exoplanets. Although they are generally expected to have some similar properties, free-floating brown dwarfs are easier to study than giant exoplanets. Usually, the glare from the host star hides giant exoplanets, making them difficult to observe.
Two of the brown dwarfs found in the study also have evidence of unidentified hydrocarbons, molecules made of both hydrogen and carbon atoms. NASA’s Same infrared signature detected on Cassini mission In the atmospheres of Saturn and its moon Titan, and in the gas between the stars.
“This is the first time this molecule has been detected in the atmosphere of an object outside our solar system,” Alves de Oliveira said. “Models for brown dwarf atmospheres do not predict its existence. We are observing objects that are younger and lower in mass than ever before, and we are seeing something new and unexpected.”
Crisis of identity of stars and planets
The question remains whether brown dwarfs are considered stars or rogue planets ejected from planetary systems.The research team believes that the brown dwarfs in this study are Most likely a brown dwarfand not the ejected planet.
Although the rogue planet theory cannot be completely ruled out, it is unlikely. Most of the stars in cluster IC 348 are low-mass, and the research team believes it to be low-mass. It is unlikely that they will be able to generate giant planets. It is also possible that during the cluster’s 5 million year existence, there was not enough time for gas giant planets to form and be ejected from the planetary system.
Discovering more objects like these brown dwarfs could help clarify their status as stars or planets. Some theories suggest that rogue planets are more likely to be found on the outskirts of star clusters. Expanding the search area may reveal their presence within IC 348.Future investigations may take more time longer investigation It can capture darker and smaller objects.
