The Mysterious Galaxy
Scientists may have finally hit upon the possible mysterious sources that have pumped heat and kept alive the fiery hot gas. They recently detected this gas but so far, they haven’t explained it completely.
There is more gas than stars in our galaxy. The prevailing, massive gas reserve is the main source for star formation in our galaxy. The availability of such abundant gas helped sustain this process till date. However, because of its tenuous nature, astronomers have found it extremely difficult to see. Also, they haven’t been able to measure the volume of this gaseous matter.
But a few decades ago, studies established the presence of gaseous matter surrounding our galaxy, the Milky Way. A large sphere of gas which was a few million degrees Kelvin hot, surrounded the galaxy. This sphere of gas extended to 700 thousand light years. Such high temperatures, researchers said, could be associated with the gravity of the Milky Way. This was because atoms would have to constantly swirl around to escape the galaxy’s strong gravity.
New Discoveries
But a discovery intrigued the scientific community further. It was gaseous matter which was even hotter than what was known previously. This latest discovered gaseous matter was pitched to be around ten million degrees Kelvin. Faint X-ray emissions from all directions of the Milky Way bore a strong signature of a super-hot gas. At the same time, this gas also showed up in the spectra of at least three distant quasars, as an absorbing medium.
A keenly studied research area emerged, and, since then, astronomers have been trying to find clues and links to the sources that were pumping heat and keeping alive the fiery hot gas.
Scientists at the Raman Research Institute (RRI), an autonomous institute funded by the Department of Science and Technology (DST), Government of India, along with their collaborators at IIT-Palakkad and Ohio State University, have detailed the mysterious source through their proposed model in two related studies.
They have confirmed that the gas responsible for emitting and absorbing the signals detected by astronomers were not the same. Instead, a puffed-up region around the stellar disc of the Milky Way caused the X-ray emitting hot gas. Since there is a continuous on-going star formation at various regions across the disk of the Milky Way, the massive stars in these regions explode as supernovae, and heat the gas around the disk to high temperatures.
“As such, explosions keep heating up the gas floating around the disc of the Milky Way and they enrich the gaseous matter with elements synthesized within massive stars,” said Mukesh Singh Bisht, PhD student at RRI.
This turbulent gas is swept up from the disc and swirls around violently. Consequently, it either escapes into the surrounding medium or cools and falls back onto the disc.
The Absorbing Hot Gas
In absorption studies, the superhot temperatures of the vast gaseous matter and its elemental composition surprised the astronomers. This absorbing hot gas has α-elements.
“This fiery gas, at least in a few directions, seems to be enriched with large quantities of α-elements, such as Sulphur, Magnesium, neon etc., whose nuclei are nothing but multiples of Helium nuclei. This is a vital clue of nuclear reactions occurring within the stellar core. These elements are thrown out of massive stars during supernovae explosions,” explained Biman Nath, faculty, RRI, and one of the contributory authors in both the papers.
Even though thousands of run-away stars constantly eject out of the Milky Way disc, some behave differently. They may hover above the stellar disc and explode as supernovae. Consequently, they create a puff of α-enriched and fiery 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 disc, as a result of the star forming activities in the stellar disc of the Milky Way which explains the hot gas seen in X-ray emission,” said Bisht. The study appeared in the Astrophysical Journal.
Scientists can study the faint X-ray signals to obtain more clues. The group plans to test the models in other frequencies.
Related Image
Image: Flickr
Figure Caption: This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy. This merger will unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger
Download the full article, to read it offline:
*****
Want to stay informed and inspired? Subscribe to our blog for insightful updates delivered straight to your inbox. Explore our website for a curated collection of reference books, resources, and more . It will fuel your curiosity and keep you ahead.