This image from Webb’s NIRCam instrument shows the central portion of star cluster IC 348. Image credits: NASA / ESA / CSA / STScI / K. Luhman, Pennsylvania State University / C. Alves de Oliveira, ESA.
Brown dwarfs are cold, dark objects that are between the size of gas giant planets and Sun-like stars.
These objects, also known as failed stars, have star-like properties even though they are too small to sustain hydrogen fusion reactions in their cores.
Typically, their masses are between 11 and 16 Jupiter (the approximate mass that can sustain deuterium fusion) and 75 and 80 Jupiter (the approximate mass that can sustain hydrogen fusion).
“One of the basic questions you’ll find in any astronomy textbook is: What is the smallest star? That’s what we’re trying to answer,” said Kevin, an astronomer at Penn State University.・Dr. Luman said.
The newly discovered brown dwarf resides in IC 348, a star cluster 1,000 light-years away in the constellation Perseus.
The cluster, also known as Collinder 41, Gingrich 1, and Theia 17, contains nearly 400 stars and is about 5 million years old.
IC 348 is part of the larger Perseus star-forming region, and although it is normally invisible to the naked eye, it shines brightly when viewed at infrared wavelengths.
Dr. Luhmann and his colleagues used the following method to image the center of the star cluster. Webb’s NIRCam device Identify brown dwarf candidates based on their brightness and color.
They followed up on the most promising targets using: Webb’s NIRSpec microshutter array.
This process created three interesting targets with masses between three and eight Jupiters and surface temperatures between 830 and 1,500 degrees Celsius.
Computer models suggest that the smallest of these weighs just three to four times as much as Jupiter.
ESA astronomer Dr Catalina Alves de Oliveira said: “With current models, it is very easy to create a giant planet in a disk around a star.”
“But in this cluster, the object is unlikely to form as a disc, but instead as a star, with three Jupiters having a mass 300 times less than the Sun.”
“Then we have to ask how the star formation process takes place at such a very small mass.”
Two of the brown dwarfs identified by the research team exhibit spectral signatures of unidentified hydrocarbons, molecules that contain both hydrogen and carbon atoms.
The same infrared signature was detected in the atmospheres of Saturn and its moon Titan by NASA’s Cassini mission.
It has also been observed in the interstellar medium, the gas between stars.
“This is the first time this molecule has been detected in the atmosphere of an object outside our solar system,” Dr de Oliveira said.
“Models for brown dwarf atmospheres do not predict their existence. We are observing objects that are younger and have lower masses than ever before, and we are seeing something new and unexpected.” .”
a paper Regarding the survey results, astronomy magazine.
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KL Luman other. 2023. JWST survey of planetary mass brown dwarfs in IC 348. A.J. 167, 19; doi: 10.3847/1538-3881/ad00b7
Source: www.sci.news
