Here is a region of intense star formation, partially hidden by thick dust, just 300 light years from the supermassive black hole at the center of our galaxy. Best of all, the scene was photographed in all its spectacular glory by none other than the James Webb Space Telescope (JWST).
This star-forming region, known as “Sagittarius C,” features 500,000 stars scattered like glitter on a bluish background. One of the main attractions itself owes itself to the Near Infrared Camera (NIRCam) of the James Webb Space Telescope and involves members of a dense cluster of baby stars, or protostars, visible just left of center. Also within this cluster is a burgeoning star that has already gathered a mass 30 times that of our planet. sun‘s, but continues to grow. For this star, life will be short. In a few million years, the ultra-massive object will explode like a supernovaunlike the stars with masses similar to our sunIt’s one that can survive for billions of years.
Stars form inside clumps of cold, dense molecular hydrogen that collapse in on themselves under the influence of gravity. These clusters are filled with interstellar dust that helps keep temperatures within 10 degrees of absolute zero – absolute zero being the coldest temperature theoretically possible in our universe. In some places, the broad bands of dust are so thick that even the JWST’s infrared vision cannot penetrate them.
However, we know that deep within these clouds are infant stars that are just beginning to form. Some of these stars, like the protocol shown here, have reached a stage where their winds can blow away these dusty bellies, making the stars themselves visible.
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Analysis of this new JWST image of Sagittarius C, captured by an international team studying star formation in the Galactic Center, or heart of the Milky Way, is led by University of Virginia undergraduate student Samuel Crowe in Charlottesville.
“We’re seeing many features here for the first time,” Crowe said in a statement. statementreflecting on the superior resolution and sensitivity of the JWST’s 6.5 meter mirror, which is the largest space telescope ever launched.
Among these features are the outflows of protostars that glow like fire when confronted with the darker, more opaque cloud of molecular hydrogen. In front of this dark cloud, at the top of the image, are stars in the foreground; Around the lower edge are sections of bright, ionized hydrogen, energized by ultraviolet light from other young, massive stars.
This ionized hydrogen had been detected before, the team says, but the sheer size of the region – 25 light-years across as seen by JWST – was a surprise. Crowe intends to study this discovery further, as well as track down the identity of the “needles,” or elongated shards that pass radially through the ionized gas in seemingly random directions.
Located approximately 26,000 light years away, the Galactic Center is deliberately targeted by astronomers using the JWST because it is a very intense star forming region. Indeed, in some ways the Galactic Center shares similarities with the first star-forming galaxies that JWST discovered existed just a few hundred million years after the Big Bang. These galaxies appear brighter than expected; one possible reason is that they form more massive stars than older galaxies.
“The Galactic Center is the most extreme environment in our galaxy, the Milky Way, where current theories of star formation can be put to their most rigorous tests,” said Jonathan Tan, one of the supervisors of Crowe at the University of Virginia.
In particular, astronomers are looking to determine whether massive stars are more likely to form in star birth regions at the center of our galaxy than in the suburbs of the Milky Way’s spiral arms. Generally, stellar nebulae give rise to the least massive stars, Dwarves M – and the increase in stellar mass leads to a drop in the birth rate. This is illustrated by the fact that there are only a handful of the most massive stars in the Milky Way, hundreds of times the mass of our sun.
This tendency to form more of the least massive stars and fewer of the most massive stars is called the stellar initial mass function (IMF), and astronomers still don’t fully understand what governs it. However, the intensity of star formation in the Galactic Center could overturn the IMF, leading to the preferential formation of a greater abundance of massive stars. If this turns out to be the case, it could also apply to early galaxies. If they had a higher IMF than we thought, that could explain why they are so luminous since the most massive stars shine the brightest.
“The Galactic Center is a crowded and tumultuous place,” concluded Rubén Fedriani, a member of Crowe’s team from the Instituto Astrofísica de Andalucía in Spain, in the same press release. “There are turbulent, magnetized clouds of gas that form stars, which then impact the surrounding gas with their winds, jets and radiation. Webb has given us a ton of data on this environment extreme, and we’re just starting to dig deeper into it.”