Like opening a cosmic Russian doll, astronomers peered into the center of the Milky Way and discovered what appears to be a miniature spiral galaxy, swirling delicately around a single large star.
The star — located at about 26,000 Light years of Earth near the dense and dusty galactic center – is about 32 times more massive than the sun and sits in a huge swirling disk of gas, known as the “protostellar disk”. (The disk itself is about 4,000 astronomical units wide, or 4,000 times the distance between Earth and the sun).
Such discs are widespread throughout the universe, serving as stellar fuel that helps young stars grow into large, bright suns for millions of years. But astronomers have never seen one like this before: a miniature galaxy, orbiting dangerously close to the center of our own galaxy.
How was this mini-spiral born, and are there others? The answers could lie in a mysterious object, about three times more massive than Earth’s sun, hidden just outside the spiral disk’s orbit, according to a new study published May 30 in the journal natural astronomy (opens in a new tab).
Using high-definition observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, the researchers found that the disk does not appear to be moving in a way that would give it a natural spiral shape. Instead, they wrote, the disc appears to have literally been jolted by a near-collision with another body – possibly the mysterious triple-sun-sized object that is still visible nearby.
To test this hypothesis, the team calculated a dozen potential orbits for the mysterious object, then ran a simulation to see if any of those orbits could have brought the object close enough to the protostellar disk to transform it. spiral. They found that, if the object was following a specific trajectory, it could have hovered over the disk about 12,000 years ago, disturbing the dust just enough to give the vivid spiral shape seen today.
“The fine match between analytical calculations, numerical simulation, and ALMA observations provides strong evidence that the spiral arms in the disk are relics from the intrusive object’s flyby,” study co-author Lu Xing, a research associate at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, said in a press release.
In addition to offering the first direct images of a protostellar disk at the center of the galaxy, this study shows that external objects can whip stellar disks into spiral shapes that are typically only seen at galactic scale. .
And because the center of the Milky Way is millions of times more star-dense than our neck of the galaxy, it’s likely that near-miss events like this happen quite regularly at the galactic center, the researchers said. This means that the center of our galaxy could be overloaded with miniature spirals, just waiting to be discovered. Scientists might not reach the center of this cosmic nesting doll for a very long time.
Originally posted on Live Science.