The disk of our home, our galaxy, the Milky Way, is larger than we previously thought. This has been shown by a recent study published in the journal Astronomy & Astrophysics. The work shows that a spacecraft traveling at the speed of light would take up to 200,000 years to traverse the entire galaxy . A not inconsiderable amount.
Analyzing metals
The researchers made this finding after analyzing the abundance of metals (heavy elements) in stars, also known as the metallicity of stars. Looking beyond the previously assumed boundary of the Milky Way disk, scientists were surprised to see stars with compositions that resemble those of a disk.
“We have shown that there is an appreciable fraction of stars with greater metallicity, characteristic of disk stars, beyond the previously assumed limit on the radius of the galaxy’s disk,” commented study co-author Carlos Allende, a researcher at the Institute of Astrophysics. de Canarias (IAC) in a statement.
Bigger than we thought
The study estimates the size of the Milky Way disk at 200,000 light years in diameter. Previous research has suggested that the Milky Way is between 100,000 light years and 160,000 light years in diameter. (Recall that a light year is the distance that light travels in a year, approximately 10 trillion kilometers.)
To put the finding in perspective with the location of our own star, the Sun, astronomers claimed that the newly found stars in the disk are about three times farther from the center of the galaxy than the Sun. There may be even more stars in disk four times farther, the astronomers added.
The experts made this finding after analyzing survey data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also known as the Guo Shoujing Telescope (LAMOST), which they collect the spectra of the stars. The spectrum of a star is the breakdown of its light into different colors. By analyzing the color pattern, scientists learn what elements are present inside the star.
It is not the first time, nor will it be the last
It is not the first time that scientists have reviewed the parameters of a galaxy. Another recent study of our neighbor, the Andromeda galaxy, revealed that this celestial body is actually nearly the same mass as the Milky Way, rather than larger, as previously thought as well. This affects the predictions of the motions of the two galaxies as they head for an inevitable collision. Something that will take place in a long time: in 4,000 million years.
Reference: López-Corredoira, M. et al. Disk stars in the Milky Way detected beyond 25 kpc from its center . Astronomy & Astrophysics. DOI: 10.1051 / 0004-6361 / 201832880
Image credit: R. Hurt, SSC-Caltech, NASA / JPL-Caltech
