Astrophysicists Discovered Strange New Objects in Our Galaxy ‘Unlike Anything Else'

Yahoo

2 days ago

Here's what you'll learn when you read this story:
The Central Molecular Zone, spanning 700 light-years across the heart of the galaxy, contains a majority of the dense gas in the Milky Way.
While analyzing this region with the Atacama Large Millimeter/submillimeter Array (ALMA), an international team of scientists discovered a slew of strange "slim filaments" unassociated with star-forming regions.
The filaments are likely part of what the researchers call "space tornadoes," which distributes material throughout the CMZ efficiently.
It's been little more than half a century since scientists first proposed that a supermassive black hole lies at the heart of the Milky Way. And in the decades since, we've discovered a remarkable amount about our particular corner of the universe—but there's always more to learn.
One area that remains a particular mystery is the Central Molecular Zone, or CMZ, which stretches some 700 light-years across at the heart of the galaxy. This region contains roughly 80 percent of all dense gas in the Milky Way, which—according to the Harvard & Smithsonian Center for Astrophysics—accounts for about tens of millions of solar masses of material. Home to giant molecular clouds and numerous star-forming clusters, the CMZ is a swirling mystery, and there is no other place in the galaxy like it.
Now, a new study—led by a team of astrophysicists drawing upon data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile—is adding another curiosity to this already head-scratching region of the galaxy: unexpected 'slim filaments' that have left astronomers guessing at their origin. Details of this surprising discovery were published in the journal Astronomy & Astrophysics.
An array of 66 radio telescopes located under the remarkably clear skies of the Chajnantor Plateau in the Atacama Desert, ALMA (as its name suggests) is particularly well suited to examining the CMZ thanks to its high angular resolution and its ability to trace certain molecules found in abundance in this region of space. Among those molecules is silicon oxide (SiO), which serves as a tracer for shockwaves in the CMZ. By tracing the spectral lines of SiO, astronomers can better understand this chaotic environment—and, as it turns out, discover previously unknown filament structures.
'SiO is currently the only molecule that exclusively traces shocks, and the SiO 5-4 rotational transition is only detectable in shocked regions that have both relatively high densities and high temperatures,' Kai Yang, lead author of the study from Shanghai Jiao Tong University, said in a press statement. 'This makes it a particularly valuable tool for tracing shock-induced processes in the dense regions of the CMZ. When we checked the ALMA images showing the outflows, we noticed these long and narrow filaments spatially offset from any star-forming regions. Unlike any objects we know, these filaments really surprised us. Since then, we have been pondering what they are.'
Using the SiO emission lines (along with those of eight other molecules), the astronomers confirmed that their velocities were inconsistent with outflows, show no association with dust emission, and are in hydrostatic equilibrium—a delicate balance between gravity and pressure. All these anomalous findings, packaged alongside insights like 'unlike any objects we know, ' inspire fantasies of massive alien structures hiding out in the heart of our galaxy. But the astronomers have a more science-based explanation, and it is no less mesmerizing.
'We can envision these as space tornados: they are violent streams of gas, they dissipate shortly, and they distribute materials into the environment efficiently,' Xing Lu, a co-author of the study from Shanghai Astronomical Observatory, said in a press statement. 'Our research contributes to the fascinating Galactic Center landscape by uncovering these slim filaments as an important part of material circulation.'
The authors theorize that these filaments may be part of a depletion-replenishment cycle at the heart of our galaxy. First, shock waves create these filaments. Then, as these filaments dissipate, they 'refuel' shock-released material in the CMZ and freeze back into dust grains. As scientists delve deeper into the mysteries of these filaments—and if they're as widespread as this particular ALMA sample would suggest—then we may have uncovered an important cyclic process that lies at the heart of our galaxy.
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