The Pivotal Role of Radio Astronomy in Revealing the Structure of the Milky Way.
The understanding of the marvelous structure of our home galaxy, Milkyway, was made possible by radio astronomy. Radio astronomy, subfield of astronomy that studies celestial objects at radio frequencies. It is conducted using large radio antennas referred as radio telescopes that are either used singularly or with multiple linked telescopes.
????The sources of radio emissions are Milkyway galaxy , radio galaxies, quasars, pulsars and masers. Observations of galaxy clusters in the radio wavelengths provide information about their content and structure in much detail.
????Radio observations of neutral hydrogen played a pivotal role in mapping the milky? way structure. Strong radio waves originating from the galactic centre led to the discovery of black holes, the gigantic enigma of our universe.?
????The very thought of mapping the galaxy we are residing in is a great achievement of human endeavour indeed.
Ever wondered how was the structure of our milky way galaxy determined when we can only see certain part of it?? As viewed from earth, the visible region of the milkyway’s galactic plane occupies an area of the sky that includes 30 constellations. It is due to our place in the milkyway galaxy. The sun is located within the orion arm located between the arm of perseus and Sagittarius of the milkyway Galaxy. As a result the spiral part is not visible to us.The galactic centre, its opposite region i.e the galactic anticenter and the space between them where resides the famous orion constellation are visible. The? most luminous part of the milkyway visible to us is the galactic centre which is in the same plane as our solar system.
The visible light cannot pierce through huge gas clouds and heavy star dusts. This is where radio astronomy comes into play.
Radio waves can’t be stopped from reaching to us by all those heavy star dust and huge gas clouds covering our milky way galaxy. These radio waves are detected and converted into electrical signals by antennas. These electrical signals can then be processed to extract information about various celestial phenomenon happening inside our home galaxy.
The prime source of the radio waves conducive for mapping the structure of the milkyway galaxy is hydrogen, specifically neutral hydrogen (H I). Hydrogen is the fuel for various celestial occurrences such as star formation, molecular clouds, etc. In region with higher concentrations of molecular hydrogen, the likelihood of star formations increases. Various stellar events can affect its overall distribution throughout a galaxy.?
The interstellar medium is the material (mostly gas and dust) that fills the space between stars in a galaxy. Hydrogen is a major component there too. Its concentration varies, and different regions exhibit different phases of hydrogen (atomic, molecular) depending on factors such as temperature and pressure. The central region of the Milky Way, including the galactic bulge and the supermassive black hole at the center, exhibits a higher concentration of hydrogen. This is likely due to the gravitational influence of the central bar and the presence of intense stellar activity.
The distribution of hydrogen varies according to the intergalactic dynamics so does the radio waves originating from them. Their concentration is often higher in the spiral arms compared to inter arm region, unravelling to us the gigantic spiral arms of milky way.
The neutral hydrogen emits and absorbs radio waves at a specific wavelength of 21 cm called the 21-cm emission line of hydrogen. Radio telescopes on Earth can detect these 21-centimeter radio waves coming from neutral hydrogen in space.
By observing these radio waves from different parts of the sky, astronomers created maps of the distribution of neutral hydrogen in our galaxy leading to mapping the entire structure of our galaxy.
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CONCLUSION-
This is how observations, particularly in the radio wavelength, played a critical role in mapping the distribution of hydrogen and studying its properties in different regions of the Milky Way.
The discovery of the spiral arms and the gigantic galactic centre residing the haunting black hole Sagittarius? A has been one of the huge achievement in understanding the overall structure of milkyway and further increasing our knowledge about ?the universe in particular. This was just a tiny spec of what wonders watching the universe in the radio wavelength can bring to us.
REFERENCES-
[2]. ttp://spiff.rit.edu/classes/phys230/lectures/mw_struct/mw_struct.html
IMAGE CREDITS-
Student at VIT Pune.
5 个月Very Insightful !!, I'm also looking forward to study in radio astronomy, as currently I had nothing to minimum knowledge about radio astronomy. This article gave me inspiration to study about it. ?? ?? ?? ?? ??