Astronomers have gazed into the core of the Milky Way and discovered what looks to be a small spiral galaxy revolving daintily around a single big star, as if breaking open a cosmic Russian nesting doll.
The star is around 32 times as big as the sun and lies amid a gigantic disk of spinning plasma known as a "protostellar disk," which is located about 26,000 light-years from Earth near the thick and dusty galactic core. (The disk is 4,000 astronomical units broad, or 4,000 times the distance between the Earth and the Sun.)
Throughout the cosmos, such disks serve as stellar fuel, allowing nascent stars to evolve into large, luminous suns over millions of years.
But scientists have never seen anything like it: a small galaxy circling uncomfortably near to the galactic core.
I'm curious in how this mini-spiral came to be, and whether there are any more like it.
According to a recent research published in the journal Nature Astronomy on May 30, the answers might be found in a mystery object around three times the mass of the sun lying just beyond the spiral disk's orbit.
The researchers discovered that the disk does not appear to be moving in a way that would give it a natural spiral structure using high-definition data collected with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.
Rather, they write, the disk appears to have been literally agitated by a near-collision with another body – likely the mystery triple-sun-sized object that can still be seen nearby.
To test this theory, the researchers computed a dozen possible orbits for the strange object and performed a simulation to determine whether any of them might have taken it close enough to the protostellar disk to cause it to spiral.
They discovered that if the item had followed a precise route, it might have skimmed by the disk roughly 12,000 years ago, perturbing the dust just enough to produce the brilliant spiral form that can be seen today.
