A team of astronomers has been able to deduce the thickness of the inner and outer regions of our galaxy, the Milky Wayto discover a drastic and surprising difference between the two.
Scientists at the Green Bank Observatory (GBO) of the National Science Foundation (NSF) of the United States, who were trying to study the so-called Smith cloudhidden behind dense layers of gas and dust in the Milky Way.
The Smith Cloud, which contains enough gas to fill a million suns, is expected to crashes into the Milky Way in about 27 million years. Astronomers have been intrigued by this monstrous high-speed cloud since its discovery in the 1960s. The Green Bank Telescope (GBT) and the GBO’s 20-meter telescope, along with the NASA/ESA Hubble Telescope, are the main tools that have been used to study this enormous and mysterious body of gas.
The GBO scientist Tony Minter planned to observe the place where part of the Smith Cloud is now interacting with the Milky Way. At this distance, and on the other side of the galaxy, this observation is complicated, even for a telescope as sensitive as the GBT. Minter looked for dust and weak emissions of hydroxyl molecules (OH). The Smith Cloud should have very little or no dust and OH, while most clouds in the Milky Way contain both. If Minter found an accretion area in the galaxy where parts of the Smith Cloud had begun to mix, he would see the differences in their composition and learn more about this interaction.
“I knew there was a low chance that I would find what I was looking for, and I didn’t,” Minter admitted in a statement, “but this is all part of the scientific process. You learn from what you find and what you don’t find.
Instead, Minter’s observation revealed information about the structure of the inner part of our galaxy. While observing the Milky Way for OH molecules in his target area, Minter determined the thickness of the molecule layer in the inner galaxy.
This revealed the molecular gas scale height in the inner Milky Way, which measures about 100 parsecs, or 330 light years, in diameter. Observations of molecules in the outer parts of the Milky Way are about 200 parsecs, or twice the thickness.
What does this mean for what scientists know about the Milky Way? Minter adds: “All I can say currently is that the data we see from this part of the inner galaxy shows that it is different from the outer galaxy. We need more observations to learn more about what this means. “That’s why astronomy is exciting, our knowledge is always evolving.”
