An international team of astronomers has detected the first brown dwarf candidate in the outer Milky Way star cluster NGC 602 using the NASA/ESA/CSA James Webb Space Telescope. Enlarged image – ESA/NASA
Imagine the outskirts of the Small Magellanic Cloud, a satellite galaxy of the Milky Way, about 200,000 light-years from Earth. Here we find the young star cluster NGC 602. The local environment of this cluster is similar to that of the early Universe. , contains almost no elements heavier than hydrogen or helium.
The presence of dark clouds of dense dust and the fact that the cluster is rich in ionized gas also suggest that star formation is occurring. with associated HII [1] Region N90 contains a cloud of ionized atomic hydrogen, and the cluster provides a rare opportunity to study how stars form under conditions dramatically different from those near the Sun.
An international team of astronomers including Peter Zeidler, Elena Sabbi, Elena Mangiavakas and Antonella Nota used the Webb to observe NGC 602, the first young brown dwarf star outside the Milky Way. I found a candidate.
“The incredible sensitivity and resolution in the right wavelength range allows us to detect objects at such great distances,” said Peter Zeidler, lead author of the European Space Agency’s AURA/STScI. . “This has never been possible before, and will continue to be impossible for ground-based telescopes for the foreseeable future.”
Brown dwarfs are more massive relatives of gas giant planets (Jupiter typically has a mass of around 13 to 75, and sometimes less). They are free floating. In other words, they are not gravitationally bound to the star like exoplanets. However, some of them share characteristics with exoplanets, such as atmospheric composition and storm patterns.
“So far, around 3,000 brown dwarfs are known, and they all live in our galaxy,” added Elena Mangiavakas, a team member at the European Space Agency AURA/STScI. Ta.
“This discovery highlights the ability to use both Hubble and Webb to study young star clusters,” said team member and executive director of the International Space Science Institute in Switzerland and former ESA Webb Project Scientist. explained Antonella Nota. “Hubble showed that NGC 602 hosts very young, low-mass stars, but only Webb could conclusively confirm the extent and significance of substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”
“Brown dwarfs seem to form similarly to stars, but they just haven’t gained enough mass to become full stars. Our results are in good agreement with this theory,” Peter said. said.
The research team’s data includes new images from NGC 602’s Webb Near-Infrared Camera (NIRCam). This image shows cluster stars, young stars, and surrounding gas and dust ridges. Also visible are numerous background galaxies and other stars in the Small Magellanic Cloud. These observations were made in April 2023.
“These are analogues of the first giant exoplanets outside the Milky Way,” Elena added. “We need to prepare for breakthrough discoveries on these new objects!”
These observations were made as part of JWST GO program #2662 (PI: P. Zeidler). The results were published in The Astrophysical Journal.
Precautions
[1] Some of the most beautiful extended objects we can see are known as HII regions, also called diffuse or emission nebulae. They primarily contain ionized hydrogen and are present throughout the interstellar medium of the Milky Way and other galaxies.
Detailed information
Webb is the largest and most powerful telescope ever launched into space. Under an international cooperation agreement, ESA provided the telescope’s launch services using an Ariane 5 rocket. ESA, in collaboration with its partners, was responsible for the development and certification of Ariane 5 adapted for the Webb mission and the procurement of launch services by Arianespace. ESA also provided 50% of the flagship spectrometer NIRSpec and the mid-infrared instrument MIRI, designed and built by a nationally funded consortium of European research institutes (MIRI European Consortium) in collaboration with JPL and the University of Arizona. did.
Webb is an international partnership between NASA, ESA, and the Canadian Space Agency (CSA).
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