By now, astronomers are used to the James Webb Space Telescope pushing the boundaries of astronomy, so it’s no surprise that the $10 billion telescope has surpassed itself once again.
The James Webb Space Telescope (JWST), with a little help from the Hubble Space Telescope, has discovered a family of so-called “failed stars” brown dwarfs in the Small Magellanic Cloud (SMC), a satellite galaxy of the Milky Way. Possibly. If true, this would be the first time astronomers have discovered such an object beyond the limits of our galaxy.
The potential brown dwarf is located in a young star cluster called NGC 602, at the edge of the SMC, a dwarf galaxy near the Milky Way. NGC 602 is approximately 200,000 light-years from Earth. This cluster is often studied by astronomers because the thick clouds of dust and gas that make up the star body are thought to be the site of intense star formation. Star formation in this region of the SMC is further evidenced by an associated patch of ionized hydrogen called N90. Atomic hydrogen is created when intense ultraviolet light from young stars strips electrons from hydrogen atoms.
Also, due to the lack of elements heavier than hydrogen and helium (astronomers call these heavier elements “metals”), regions like NGC 602 and the broader SMC are similar to those found in the early universe. It is a good proxy for galaxies that are “poor in metal.” .
“By studying the young, metal-poor brown dwarfs newly discovered in NGC 602, we are getting closer to uncovering the secrets of how stars and planets formed under the harsh conditions in the early universe,” the team said. said member Elena Sabbi, a scientist at the University of Arizona. statement.
The same dense lanes of gas and dust make these regions interesting to study. However, these same lanes absorb visible light, creating a challenge for astronomers.
Long-wavelength, low-frequency infrared radiation passes through these clouds without being absorbed. This is the wavelength of light at which JWST studies the universe. This will use JWST’s near-infrared camera (NIRCam) and mid-infrared instrument (MIRI). ) Ideal for SMC and NGC 602 research. No wonder this powerful space telescope has once again broken new ground with the potential detection of the first extragalactic brown dwarf star.
Brown dwarfs fail…
Brown dwarfs have the slightly unfair nickname of failed stars. That’s because brown dwarfs form like stars from collapsing clouds of too dense gas and dust, but they only have masses between 13 and 75 times that of Jupiter (0.13 to 0.75 times the mass of the Sun). This means it cannot generate enough pressure and heat to cause the fusion of hydrogen to helium in its core, the process that defines main sequence stars.
Brown dwarfs differ from planets not only in the way they form. Unlike most planets, these objects also wander through space untethered to their parent star. they are do It shares some characteristics with gas giant planets, such as the composition of its atmosphere and the storms that rage there.
So far, astronomers have detected about 3,000 brown dwarfs, all within the boundaries of the Milky Way. These extragalactic brown dwarfs seem to support theories about how budding stars fail.
“Our results are in very good agreement with the theory that the mass distribution of objects below the hydrogen burning limit is simply a continuation of the stellar distribution,” team member ESA scientist Peter Zeidler said in the same statement. said. “They seem to form in the same way, they just don’t accumulate enough mass to become full stars.”
…but JWST succeeds
In addition to showcasing groundbreaking science, the JWST/NIRCam/MIRI data collected as part of JWST GO program number 2662 also brought us stunning images of NGC 602.
“This discovery highlights the ability to study young star clusters using both Hubble and JWST,” said team member and executive director of the International Space Science Institute in Switzerland and former ESA JWST project. said scientist Antonella Nota in a statement. “Hubble has shown that NGC602 hosts very young, low-mass stars, but only using JWST will we be able to conclusively confirm the extent and significance of substellar mass formation in this cluster. You can.
“Hubble and JWST are an amazingly powerful telescope duo!”
An image of NGC 602 taken in April 2023 shows the surviving star cluster and its surrounding dust lanes and gas clouds. These signals the beginning of a new era of studying local metal-poor galaxies in detail, something not possible for the universe’s oldest hydrogen- and helium-dominated galaxies billions of light-years away. .
“It takes incredible sensitivity and spatial resolution in the right wavelength range to detect objects at such great distances,” Zeidler concluded. “It has never been possible and will remain impossible from the ground for the foreseeable future.”
The research team’s work will be published in The Astrophysical Journal on October 23rd.
