New scientific results are much more exciting when they become widely accepted facts on their heads.
Until recently, it was assumed that our neighboring Calaxi Andromeda was far larger than the Libra – more than twice as large as our home calves. Later studies showed that Andromeda and the Milky Way were actually about the same size. But now, new research has shown that the Growth Road is much larger than previously assumed, and actually peaks in Andromeda.
According to a report published by the European Space Agency (ESA), researchers have calculated the mass of our galaxy with new precision.
Combining data from ESA's Gaia space probe and data from the Hubble Space Telescope ̵
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The reason why previous calculations were not quite accurate is due to " dark matter "a theoretical type of substance that could account for a significant amount of all matter in the universe.
Dark material cannot be detected or measured in the typical ways.
"It leads to the current uncertainty in the race mass," says Laura Watkins of the European Southern Observatory in the new report "You can't measure exactly what you can't see."
To estimate the mass of dark matter in the Milky Way, the astronomers measure the velocity of the spherical clusters – dense star clusters that orbit the spiral disk of the galaxy.
"The more massive a galaxy, the faster its clusters go under its gravity," explained astrophysicist N. Wyn Evans of the University of Cambridge.
The revolving speed of the globular clusters around the Milky Way was far greater than the visible matter in the galaxy would suggest. So the researchers were able to deduce from this anomaly that the dark matter was responsible for that extra gravity.
Using Gaia – a space probe designed to produce a precise 3D map of the Milky Way – for the first time, researchers were able to evaluate three-dimensional measurements of cluster speeds.
"Most previous measurements have found the speed at which a cluster is approaching or falling from Earth, this is the speed along our field of view," said Wyn Evans. "However, we could also measure the lateral movement of the clusters, from which the total speed and thus the galactic mass can be calculated."
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Hubble observations allowed for distant globular clusters – some as much as 130,000 light-years from Earth – added to the study.
"We were fortunate to have such a great combination of data," explained Roeland P. van der Marel of NASA's Hubble Institute. "By combining Gaia's measurements of 34 globular clusters with measurements of 12 more distant clusters from Hubble, we could turn down the mass of the wall in a way that would be impossible without these two space telescopes."
With a mass of 1.5 trillion solar masses, the Milky Way could even be the largest galaxy nearby.
This also means that a potential future collision and fusion of the two galaxies would look quite different from what the researchers had previously depicted. So far, it was assumed that Andromeda would consume the Growth path, but according to these recent results, conversely, may be true.