There is more gas in the Milky Way than stars. Some of it is extremely hot. Recently, scientists have modeled the general picture of where all this matter is concentrated and how it goes from one state to another.
Interstellar gas in our galaxy
Scientists may have finally found the possible mysterious sources that pump heat and sustain the life of the fiery-hot gas that has recently been discovered around the Milky Way but has remained unexplained until now.
There is more gas than stars in our galaxy. The predominant, massive supply of gas is the main source of star formation in our galaxy. The presence of so many gases helped keep the process going until now. However, because of its rarefied nature, it has been extremely difficult for astronomers to see, let alone measure, the volume of this gaseous matter.
But several decades ago, research identified the presence of gaseous matter surrounding our galaxy, the Milky Way. The galaxy was found to be surrounded by a large sphere of gas that was several million degrees Kelvin hot. This gas sphere spanned 700,000 light-years.
Hot gas of the Milky Way
The researchers believe that such high temperatures may be related to the Milky Way’s gravity, as atoms would have to be constantly spinning around to escape the galaxy’s strong gravity.
But what intrigued the scientific community even more in recent years was the discovery of a gaseous substance that was even hotter than previously known. The temperature of this last discovered gaseous substance was about 10 million degrees Kelvin. Faint X-ray emission was detected in all directions of the Milky Way, which had the distinct signature of superhot gas. At the same time, this gas also appeared in the spectra of at least three distant quasars as an absorbing medium.
A line of research emerged that is being scrutinized, and astronomers have been trying to find clues and connections to the sources that pumped heat and kept the fiery hot gas alive ever since.
New research on the gaseous veil
Scientists from Raman Research Institute (RRI) along with their colleagues from IIT-Palakkad and Ohio State University have detailed the mysterious source using their proposed model in two related studies published in The Astrophysical Journal.
They confirmed that the gas responsible for emitting and absorbing the signals detected by astronomers was not the same. Instead, the hot gas that emitted X-rays was caused by an inflated region around the Milky Way’s stellar disk.
Since there is continuous star formation in different regions of the Milky Way, massive stars in these regions explode as supernovae and heat the gas around the disk to high temperatures.
When this turbulent gas is picked up from the disk and swirls violently, it either flies out into the environment or cools and falls back onto the disk.
Elemental composition of gas cloud
In the case of the absorption studies, along with the ultra-high temperatures that the huge gaseous matter possessed, its elemental composition also surprised astronomers. It turns out that this absorbing hot gas is enriched in α-elements.
This fiery gas, at least in several directions, seems to be enriched with a large number of α-elements, such as sulphur, magnesium, neon, etc., whose nuclei are nothing but multiples of helium nuclei. This is an important key to understanding the nuclear reactions that occur in the core of a star. These elements are ejected from massive stars during supernova explosions.
Although there are thousands of runaway stars that are constantly ejected from the Milky Way disk, when some of them, hovering above the stellar disk, explode as supernovae, they potentially create a jet of fiery α-particle-rich gas around them.
“If they fall in line with the direction of distant sources of light quasars, the atoms in this hot gas would absorb and produce shadow signals, thus explaining the absorbing hot gas. At the same time, a veil of fiery hot gas keeps engulfing the Milky Way disk, as a result of the star forming activities in the stellar disk of the Milky Way, which explains the hot gas seen in X-ray emission,” said Mukesh Singh Bisht, a PhD student at RRI.
Weak X-ray signals obtained in this way can be further studied to get more clues. The team plans to test the models at other frequencies.
Provided by phys.org
