A team of researchers from the Institute of Astrophysics of the Canary Islands (IAC) in Spain and the National Astronomical Observatories of Beijing, Japan (NAOC) have just published in the Journal Astronomy and Astrophysics, a work that suggests that, if we could travel at the speed of light, it would take 200,000 years to cross the disk of our galaxy.
The spiral galaxies, like our Milky Way, are characterized by having a disk of little thickness where most of the stars are found. These discs have a limited size and, from a certain distance, there are almost no stars.
In our galaxy, there was no evidence that there were disk stars at distances from the center greater than twice that of the Sun. That is, it was thought that our nearest star was located at the middle of the galactic radius. However, there are and far more, more than three times that distance. Even, some are likely to exceed four times that distance.
“The disk of our Galaxy is huge: about 200 thousand light-years in diameter,” said in a press release, Martín López-Corredoira, researcher at the IAC and first author of the article in which researchers from the IAC and the NAOC.
Like a disk with arms
Broadly speaking, we could imagine that galaxies such as the Milky Way are composed of a disk, in which spiral arms rotate, and a halo, with a spherical shape, that surrounds it. In the elaboration of this investigation, the abundances of metals in the stars in the galactic plane have been compared with those of the halo, to find that there is a mixture of halo and disk up to the great distances indicated.
Researchers have reached these conclusions after performing a statistical analysis of mapped data of APOGEE and LAMOST, two projects that obtain spectra of stars, that is, information about their speed and chemical composition.
“Using the metal content of the stars of the catalogs, with the combination of high-quality spectral atlases such as APOGEE and LAMOST, and the distance to which they place the objects, we have verified that there is an appreciable fraction of stars beyond where it was supposed to end the disc of the Milky Way, “explains Carlos Allende , researcher at the IAC and co-author of that publication.
For his part, Francisco Garzón, researcher at the IAC and another of the authors of the article, clarifies: “We have not made use of models, which sometimes only give the answers they have been designed for. Only statistics on a large number of objects The results are thus free from a priori assumptions, beyond a few firmly established. ”
Each new investigation on the Milky Way, gives us more information about our fascinating cosmic corner. Recently it was learned that the center of our galaxy began to form 11 billion years ago and that it grows approximately 500 meters per second.