Scientists have discovered that the reddest galaxies with the largest central bulb have the longest bars – gigantic central columns of stars and dark matter- using Google Maps.
More than two thirds of spiral galaxies, including our own Milky Way, display a central bar that can extend for thousands of light years.
These colossal elongated structures are made up of collections of stars and dark matter, which are held together by gravity.
Now, a team of researchers from Europe and the USA have measured the bar length of some 5000 galaxies with the help of amateur astronomers and released the most precise results (those obtained for 3150 galaxies).
The study comes under the Galaxy Zoo project, a citizen science initiative in which more than 200,000 volunteers assisted in classifying a million galaxies through images provided by the Sloan Digital Sky Survey astronomical catalogue.
More precisely, the team has used the Google Maps Sky interface, which allows seeing the sky especially the galaxies, as seen from the Earth’s surface.
“In this way we have compiled some 16,000 measurements of the bars of 5000 galaxies, which is a sample a hundred times greater than previous ones,” said Hoyle.
“We have also come to many different conclusions, such as the fact that redder galaxies, which are stopping star formation, have longer bars,” added Hoyle.
In the electromagnetic spectrum, the colour red comes from older, cooler stars whereas the colour blue is linked to hotter and younger stars.
The study also reveals that the bars tend to be redder than the rest of the galaxy, which indicates that they have an older stellar population.
Other conclusions indicate that those galaxies with a larger bulb (a central agglomeration of stars) have longer bars. In addition, barred galaxies are more likely to display spiral arms than unbarred galaxies.
The findings have been published in the Monthly Notices of the Royal Astronomical Society journal.