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Astronomers have discovered a giant cavity in the Milky Way surrounded by two nebulae, clouds Perseus and Taurus, which appeared after at least one giant star exploded, according to a study published Wednesday.
The molecular clouds Perseus and Taurus, as they are called, have long been the subject of observations due to their proximity to the Earth, between 500 and 1,000 light years, a negligible distance on the scale of our Milky Way galaxy, which is over 80,000 light years in diameter.
star factories
But the interest for them is also due to the fact that they shelter star factories which were formed thanks to the mixture of molecular gas and dust which compose these clouds. It also seemed that these two nebulae were connected by some kind of wire, but this hypothesis was later ruled out, given the distance between them and planet Earth.
“The funny thing about these two clouds is that you can see that they are well connected, not as you imagine, but through a giant cavity,” researcher Shmuel Bialy told AFP. Harvard Center for Astrophysics and the Smithsonian Institution.
This is the first time that scientists have been able to design a three-dimensional map of such a structure, called a “per-tau shell”, using advanced computational and imaging techniques, in particular a map of molecular gases in a larger area drawn using data from the European “Gaia” space telescope. .
And Bialy explained that you have to imagine a “kind of ball with an empty interior” or a “super bubble”, with a diameter of about 500 light years (about 4.7 million billion km), and its external atmosphere formed in part by the Clouds of Perseus and Taurus.
The interior of the cavity contains little dust, “but at a very low density compared to the density of clouds,” assistant professor at the German institute Max Planck, astrophysicist and physicist Torsten told AFP. Enslin.
Solar suburb
Enslin is co-author of this study, the results of which were published in the Astrophysical Journal Letters, with lead author Shmuel Bialy. He is one of the scientists who made in 2019 and 2020, the first three-dimensional map of dust clouds near our sun, using Gaia data on the location and characteristics of more than five million stars in this “suburb. “solar.
Kathryn Zucker, postdoctoral researcher and astrophysicist, signed up for a second study on the topic on Wednesday to explain how scientists put this map to good use, in part thanks to algorithms developed under her supervision.
“This is the first time that we can use real 3D views, not simulations, to compare theory with observation, and estimate what works best” to explain where this giant cavity and the clouds are. installed on its surface, she said in a statement quoted by a statement from the Center for Astrophysics. “We think it was caused by a supernova, a huge explosion that pushed these gases out and formed these clouds,” Bialy explained.
According to this theory, one or more stars exploded at the end of the end-of-life phase, gradually pushing back most of the gas that was swimming in them to form this cavity, between 6 and 22 million years ago.
“We are now observing the cavity in its final phase, where it has already slowed down (its expansion) and allowed the formation of the Perseus and Taurus clouds,” Bialy added. He currently intends to focus on the young star groups that appear there.
As for Professor Enslin, he expected “many other structures to be discovered” like those found at “Per-tau”, and he said: “This bubble may be one of many,” adding that despite its size, it occupies a small area in the three-dimensional map it contains. Made by his department.
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