Huge plasma bubbles emanating from the heart of the Milky Way may include debris from the entire galaxy and beyond.

A recent examination at the gas clouds in the Fermi bubbles of the galaxy reveals that they comprise material from the galaxy’s stellar disk and an unknown other source. The discovery could offer insight on how galaxies live and die in general.

The Fermi bubbles are enormous plasma blobs that span on either side of the Milky Way’s galactic disk and measure tens of thousands of light-years in height. When the bubbles were first spotted in 2010, scientists believed they were created by newborn stars (SN: 11/9/10). Currently, many astronomers believe that the bubbles may have been caused by a large, eons-old burp from the galaxy’s supermassive black hole.

In the years that followed the discovery, astronomers also observed clouds of comparatively cool gas that appeared to float among the bubbles, high above the starry disk. Astrophysicist Trisha Ashley of the Space Telescope Science Institute in Baltimore explains, “We call them high velocity clouds because we’re terrible at naming things.”

Scientists at the time of the formation of the Fermi bubbles assumed that the clouds had already been torn from the Milky Way’s dazzling star disk and launched into space. On the basis of this assumption, the age of the bubbles has been calculated, which may help shed light on their origins.

Ashley explains, “It made sense; it was a logical assumption.” “However, no one has ever investigated the source of these clouds.”

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Now, Ashley and colleagues have made their first attempt to determine where clouds originate and have discovered a surprise solution.

Using new and historical data from many telescopes, she and her team determined the metal content — the abundances of all elements heavier than helium — in 12 high velocity clouds embedded in Fermi bubbles. The researchers then matched the chemical compositions of clouds to those of stars in the Milky Way’s disk. Ashley asserts that if the clouds originated from the disk, they should include metals like the sun and other disk stars. Otherwise, their metal content should be reduced.

The study discovered a wide range of metals in the clouds, ranging from less than a fifth to more than the suns. That indicates, that these clouds must have originated in both the Milky Way’s disk and its halo, referring to the chaotic cloud of gas and dust that surrounds the galaxy and supplies fuel for new stars (SN: 7/12/18). We have found no alternative reason. How these clouds entered the halo in the first place remains a mystery, according to an astronomer at the University of Washington in Seattle who was not involved in the research.

“There are a variety of ways these clouds can form, as well as a variety of causes and outcomes,” she explains. The clouds could have condensed on their own within the halo, or they could have been ripped from smaller galaxies devoured by the Milky Way, amongst other origin myths (SN: 7/24/02). In general, this cycle is a rather untidy procedure.

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This disorder may aid in predicting how the Milky Way’s star production may evolve in the future. These cold gas clouds provide the raw material for future star formation. If such clouds formed in the Milky Way’s hazy halo, but are kept from falling into the disk to form stars by the Fermi bubbles, the galaxy’s star-making machinery could be slowed down.

Nonetheless, if the gas clouds do end up producing new stars, this may indicate that the Milky Way is constructing new stars from a variety of cosmic sources. People are ultimately interested in how the Milky Way maintains its star production over an extended period of time. Werk says. This indicates that it’s not just one item. The study of these bubbles and clouds can aid in the comprehension of other galaxies as well. Ashley states, “We can observe these events occurring in distant galaxies.” However, we have a front-row seat for this event.

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