Beacon Transcript – The spiral arms of our Milky Way Galaxy System have always posed a question to astronomers and space enthusiasts and have sparked what has come to be known as “The Debate”, but a forming spiral armed star appears to be able to provide us with a much-awaited answer.
As technology advances and we have better instruments to point towards the great outer space, a chance observation seems to provide us with the answer.
“The Debate”, which took place in 1920 was the heated discussion between famous astronomers with conflicting theories. Spiral galaxies as we now call them were known at the time as spiral nebulae and were of reason unknown. One-half of the conflict, Harlow Shapley maintained that our own Milky Way was the sole galaxy of our Solar System and that spiral arms were just clouds, possibly forming galaxies. Heber D. Curtis, the other half of the debate and the one believed to have been right, regarded the spiral nebulae as distant galaxies, not close neighbors, each with its own planetary systems.
The Atacama Large Millimeter/submillimeter Array (or ALMA), set up to see wavelengths, chanced to observe inside the gas clouds of a forming star and for the first time clearly notice its spiral arms, a reminiscence, though on a much smaller scale, of the Milky Way.
The baby star or Elias 2-27 Is being formed in the Ophiuchus star-forming complex, an area that has given birth to many stars, the most observable place of its kind and nearest in relation to our solar system. Although Elias 2-27 is just about half of the Sun, and about a fourth of its age, just coming to an approximated one million years, it has an unexpectedly big protoplanetary disk and it is hidden to most optical telescopes by molecular clouds.
Protoplanetary disks have offered glimpses of spiral arms in the past, but the density waves that are believed to have been the cause for the Milky Way’s spirals have never before been spotted into the mid-plane of one such disk, only on its outskirts.
These density waves, or gravitational perturbations, which are characteristic for forming stars were spotted by ALMA when it penetrated into the core of the disks containing Elias 2-27 who revealed itself to be a spiral armed star, sporting two arms that sprang from the body of the star to a distance of up to 10 billion kilometers.
The clear evidence of the spiral armed forming star offered by Elias 2-27 seems to confirm the inside theory of protoplanetary disk formation, only further sustained by other spiral structures discovered in developing solar systems.
Image Source: Wikipedia