The thousands of stars observable in the sky with the naked eye seem like an incredible number. However, even the billions seen by the most advanced telescopes cannot produce a complete map of the Milky Way. For this purpose, we should use radio telescopes that capture hydrogen radiation at a wavelength of 21 centimeters.
Radiation at a wavelength of 21 cm
Have you ever asked yourself how astronomers manage to map the Milky Way when it is so incredibly large? One of the most powerful tools is the so-called 21-centimeter radiation.
Hydrogen, the most common element in the Universe, has a crucial role in this. When electrons in hydrogen atoms change the direction of their spin, a special type of electromagnetic radiation with a wavelength of 21 centimeters is produced.
The Milky Way Galaxy is filled with hydrogen atoms, and these atoms are constantly emitting 21-centimeter radiation. Best of all, this radiation can travel long distances through the interstellar dust that often obscures our view of the galaxy in visible light. This makes the 21-centimeter radiation an incredibly useful tool for mapping the structure of the Milky Way.
This radiation reveals everything from the clouds of gas that form stars to the shapes of the spiral arms of a galaxy. While visible light is simply trapped in interstellar dust as it tries to move tens of thousands of light-years through the galaxy, 21 cm radiation simply flies through.
Red and blue shift in research
Astronomers can also find out about the Milky Way’s rotation by studying the red and blue shifts of the 21 cm radiation. When an object in space moves away from us, the wavelength of light or radiation it emits is stretched, causing it to appear redder (redshift). Conversely, as the object moves toward us, the wavelength is compressed, giving it a bluer color (blueshift).
Analyzing the red and blue shifts of 21 cm wavelength radiation from different parts of the galaxy, astronomers can determine how fast different regions of the Milky Way are rotating. This information helps them build a more complete picture of the dynamics and motion of our galaxy.
The benefits of 21 cm radiation are not limited to the Milky Way. Astronomers can use these same techniques to study distant galaxies. By studying clouds of neutral hydrogen gas in distant galaxies, they can estimate the masses of these galaxies. This is because the amount of 21 cm radiation is related to the number of hydrogen atoms present, which in turn gives clues about the total mass of the galaxy.
Useful mapping tool
The 21-centimeter radiation is a powerful tool in astronomy that gives astronomers the ability to map the structure of our Milky Way galaxy, understand its rotation, and even estimate the masses of distant galaxies. This method opens a window into the vast and complex Universe, helping us unravel the mysteries of the cosmos with each new observation.
Therefore, the next time you look up at the night sky, remember that there is much more going on than meets the eye. Thanks to 21 cm radiation, we can capture layers of the Milky Way and explore the wonders of the Universe in ways once unimaginable.
According to phys.org
