At the center of our galaxy lurks a supermassive black hole: a ravenous object capable of devouring matter that strays too close.
Yet new observations from the JWST suggest that right in that black hole’s cosmic neighborhood, a dying star is still casting matter back out into space.
Not all stars are massive enough to die as explosive supernovae that outshine entire galaxies like brilliant cosmic disco balls.
Instead, stars born with up to around eight times the mass of our Sun become bloated, reddish, and cool, gradually losing their outer layers into space before becoming zombified white dwarfs – and perhaps even ‘diamonds’ in the sky.
Yet whether it’s the violent chemical enrichment of supernovae or that of slowly shriveling suns, death births life: including us, because as Carl Sagan said, “We are made of star-stuff.”
Now, using the JWST, astronomers have detected some of the most important star-stuff of all, including water, dust, and other oxygen-based-chemistry products, in some of the most inhospitable conditions imaginable.
“Galactic centers are among the most extreme environments, so understanding whether stars can continue enriching their surroundings there is an important question,” explains Florian Peißker, an astrophysicist at the University of Cologne in Germany and lead author of a study detailing this discovery.
“With Webb, we can directly observe how stars behave under these conditions and see that dust production remains remarkably resilient.”
frameborder=”0″ allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” allowfullscreen>The researchers observed the inner parsec (a 3.26-light-year swathe) of the Milky Way using JWST’s Mid-Infrared Instrument (MIRI), focusing on a dominantly bright dying star called IRS 3.
IRS 3 – named because it’s an Infrared Source, not an Internal Revenue Service tax bracket – is an asymptotic giant branch (AGB) star, meaning it’s in a late stage of its life.
The star’s powerful stellar winds blast its outer layers into space at estimated speeds of 15 kilometers (9 miles) per second.
This has surrounded it with an immense dusty envelope that extends 10,000 astronomical units (AU), with one AU representing the ~150 million kilometers between Earth and the Sun.
IRS 3 is located just 0.55 light-years from Sagittarius A*, the 4-million-solar-mass monster at the scintillatingly energetic heart of the Milky Way.
As mentioned, its death throes enrich the cosmos with dust, but astronomers have long wondered whether this process can play out so close to a supermassive black hole.
So they ran multiple simulation variations to reconcile JWST’s observations with stellar models across a range of temperatures, luminosities, and chemical compositions.
Based on the models and observations, including the bow shock created as the dying star’s envelope smashes into interstellar space, the researchers inferred its most salient stats.
IRS 3 may have been born as far away as 16 light-years from the galactic center and migrated inward.
It could be about six times as massive as the Sun and approximately 72 million years old – a pup compared to our Sun’s expected 10-billion-year lifespan.
And although IRS 3 may have an effective temperature of ‘only’ 2800 K (about 4,600 degrees Fahrenheit or 2,500 degrees Celsius), compared to our Sun’s surface temperature of 5,500 °C, it may shine 60,000 times brighter.
Importantly, this work demonstrates that such stars can keep supplying chemically rich space dust and water to galactic centers, despite harsh conditions.
“This is the first time a continuous mid-infrared spectrum has been collected for this star, allowing us to detect the features from the silicate dust and uncover the star’s true chemical identity,” says Macarena Garcia Marin, an ESA scientist for Webb’s MIRI instrument and one of the study’s co-authors.
frameborder=”0″ allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” allowfullscreen>Indeed, as the star pulses in its death throes, it ‘coughs up’ its bloated outer layers, creating a nesting-doll-like set of shells at intervals of hundreds of years, potentially dating back to 5,000 years ago, according to a previous study.
“The detection of water is especially exciting because it shows that molecular material can survive in an environment dominated by intense radiation,” says Garcia Marin.
Related: There May Be 170 Million Black Holes Lurking in The Milky Way’s Graveyard
And when you mix star-borne water and other star-stuff with radiation, then let the ingredients ‘proof’ like a cosmic sourdough, who knows what otherworldly products may manifest.
“This tells us that even close to a supermassive black hole, stars can continue contributing material back into their surroundings,” Garcia Marin concludes.
This research was published in Astronomy & Astrophysics.
This article was fact-checked by Clare Watson and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
