Humans are like goldfish.
I mean that in the heavenly sense. Just as a goldfish can not see its shell from the outside, our position in the universe means that we can not see our home galaxy, the Milky Way, as the rest of the universe sees it.
Luckily, scientists have built the most accurate map of the Milky Way so far, using a collection of huge, bright stars. They have discovered that the Milky Way is not exactly what the artist thinks it is ̵
It's the first time that a map of young stars has been created – and the first measurement of how twisted our home galaxy is.
The article published in Nature Astronomy on February 4 describes the work of Australian and Chinese astronomers to study the classic "Cepheids" – a collection of giant, young stars in the Milky Way galaxy that can be up to 100,000 times brighter the sun. If you look at the Cepheids over time, you can see the stars pulsing, sometimes falling off, or increasing in brightness. By studying the length of these pulses, the distance between us and the Cepheids can be determined, which contributes to the creation of a map of the Milky Way.
The team recorded the positions of 1,339 Cepheids on a 3D map and built the most accurate representation of the Milky Way. We know that the Milky Way is a spiral galaxy – a thin disk with a hundred billion stars surrounding a giant black hole Center of the galaxy circles. The gravity of all these objects holds the galaxy together.
But the farther you go, the weaker is the force of gravity, and the gas that makes up the disc does not fall neatly into the thin plane that forms stars near the center. 19659005] The research team showed with the help of the Cepheids that the Milky Way is not a cosmic disk shaped like a lipless frisbee or a pancake shaped. So in terms of the pancake analogy, the Milky Way looks more like a pancake if you've just lifted it out of the pan before awkwardly dangling it on the spatula.
And the twisted shape is not necessarily unexpected – – Other spiral galaxies in the Universe have similar features.
"Many large spiral galaxies actually show distorted (S-shaped) disks in the distribution of gas in their disks," says Richard de Grijs, co-author of the study and astronomer at Macquarie University.
"The" twisting "of the disk is, we think, caused by the gravity drive of the rotating inner disk, which is pulled along the outer disk," explained de Grijs.
Strictly speaking, however, this form was a little more elaborate.
"We would need to perform (numerical) simulations of a realistic galaxy embedded in a dark matter halo to see if we can observe and reproduce the observations," says de Grijs. And with the number of stars in the Milky Way steadily increasing thanks to observations of spacecraft such as the Gaia of the European Space Agency (ESA), there is still room for maneuver to further enhance the model.
"It would also be good to validate the shape from larger objects in samples."
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