A new image produced by the James Webb Space Telescope (JWST, or Webb) sheds light on how early stars formed during the “cosmic noon” 10 billion years ago.
About 200,000 light-years away from Earth, the small magellanic cloudA satellite galaxy and one of the Milky Way’s closest neighbors, notable for its lack of metals heavier than hydrogen and helium.
The levels of these metals in a galaxy reflect a typical nearby environment for studying what galaxies were like during the early history of the universe, when it was only two to three billion years old and star formation was at its peak. Although various telescope missions have studied the Small Magellanic Cloud in the past, much remains to be understood.
Now, thanks to Webb’s high-resolution imaging, astronomers have discovered more than 33,000 young stars NGC 346 Nebula, the brightest and largest star-forming region in the Milky Way.
Connected: James Webb Space Telescope reveals first galaxy may have formed much earlier than we thought
“It’s like minutes on a field to find these things,” said Margaret Meixner, an astronomer with the University Space Research Association and one of the study’s authors. “How Powerful James Webb Is.”
Meixner shared preliminary imaging results of NGC 346 using the web on Wednesday (Jan. 11) at the 241st conference of the American Astronomical Society in Seattle.
“Ribbons of Gas and Dust”
cosmic dust It is formed when stars and planets are forming, and it hovers in the space between them – the interstellar medium – once their formation is over. As a byproduct of these processes, dust is composed of the same heavy metals as stars and planets. Until now, astronomers thought that heavy elements such as carbon, oxygen and iron — all of which are in low concentrations in the Small Magellanic Cloud — were necessary to form the dust from which the terrestrial planets eventually materialized.
So when astronomers used Webb’s powerful near-infrared camera (NIRCAM) instrument to study NGC 347, they were surprised to discover “ribbons of gas and dust” in the interstellar medium. The discovery is preliminary evidence that, despite being low on metals, NGC 347 is dusty and contains the building blocks needed to form a rocky planetary system.
Using Webb’s six NIRCam filters, the team found more than 33,000 sources of what they call “IR”. [infrared] more.” In low-mass stars, dust in the surrounding debris disk absorbs the star’s light and re-emits it at infrared wavelengths. So when astronomers detect infrared emission, it usually means that They have detected dust.
“We were very excited to see the dust around these things,” Meixner told reporters at the news conference.
Telescope missions have studied NGC 346 in the past, but this is the first time astronomers have photographed the dust. For example, now retired spitzer spacecraft It found 87 massive young stars in the same region, but it was not powerful enough to identify smaller stars. Hubble Space Telescope, also observed thousands of pre-main sequence stars scattered throughout the nebula and connected to each other through filaments of gas and dust. However, many of these stars remained unobserved because Hubble was not sensitive to the dust around these stars.
The JWST is now helping astronomers unveil dust-shrouded stars, and discover the youngest stars that Spitzer can detect, and Hubble two magnitudes smaller than pre-main sequence stars. can reduce. The discovery of star-forming regions in infrared wavelengths has allowed astronomers to discover many stars that are not visible, or have been misidentified, at optical wavelengths.
In the coming months, astronomers hope to learn more about how the process of star formation in the Small Magellanic Cloud is similar or different from what we’ve learned. They also plan to continue observing protostars in this region. These stars grow in size and composition by sucking up surrounding dust, so it remains to be seen how much of the dust seen by Webb now survives the star formation process, and eventually if there is enough to form rocky planets. .
For now, the JWST has already unveiled a large number of new young stars, and astronomers say they’re just getting started.
“We’ve just scratched the surface of this data,” Mexner said. “We’re going to go back and push it down [almost] A brown dwarf puts the limits of what we can see.”
The research is also described in a paper (opens in new tab) Published on 10 January in the preprint server arXiv.
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