After millennia of performing curious investigations into the night sky, humans have seen farther than unfathomable distances. With decades of advanced astronomical research, we know about billions of galaxies outside our own Milky Way. Yet we do not know our own galaxy fully and every once in a while a scientific discovery uncovers a weird new feature in our supergiant disc of stars.
Now, a team of scientists at two universities in China have discovered a new huge structure at the edge of the milky way. Scientists say that the newly discovered structure - named Cattail - could be the farthest and largest filament of the Milky Way. The structure is a really large long curl of gas which the astronomers discovered using observation from the Five-hundred-meter Aperture Spherical radio Telescope (FAST).
A team of astronomers led by Chong Li from Nanjing University used the radio telescope to look for H I structures - giant clouds of neutral atomic hydrogen. To find such clouds, astronomers study subtle differences in the light emitted by hydrogen to determine the structure and arrangement of the giant filament. The team started to look for H I radio emissions in August 2019 and they soon found data that indicated the presence of a really large structure. When the scientists calculated the velocity of the structure, they were surprised. The motion of the structure was consistent with the centre of the Milky Way, indicating that the structure was indeed a part of our galaxy and revealing its distance from the galactic centre. The structure is at a distance of about 71,750 light-years from the Milky Way’s centre.
Using the FASTdata, scientists estimated that the structure to be about 3,590 light-years long and 675 light-years broad. But when scientists combined their findings with HI4PI, an all-sky H I survey, they found that the structure could be even bigger, shooting up to some 16,300 light-years long.
“While these questions remain open with the existing data, the observations provide new insights into our understanding of the galactic structure,” the astronomers wrote in the research that was published on August 25 in The Astrophysical Journal Letters.