Question

Having trouble with these:

1. One of the important struggles of pioneering astronomers was trying to understand how big our galaxy is, and where the Sun is located in our galaxy. Explain how RR Lyrae stars and globular clusters were used by Harlow Shapley to answer both these questions.

2. Radio astronomy has been critical for determining the structure of our galaxy. Why is it more effective for this purpose than visible light astronomy?

3. Charlie and Monica are arguing about spiral arms. Charlie believes that spirals arms are regions where active star formation takes place, and are like “traffic jams” where the gas and dust is dense. Monica believes that the spiral arms of a galaxy are like a rigid spinning pinwheel, and the gravitational attraction of the stars to one another keeps them in rigid shape, like sparkles glued to a pinwheel. Whose explanation is more accurate, and why?

Answer 1

2. Visible Light Astronomy is geat for beginers and is still being used as a tool to gather basic information and behaviours of star or a galaxy but Radio astronomy is critical as it adds a whole different dimention to our knowledge. Radio waves are known as the oldest waves present in our universe. Having the longest wavelength ( even few km) , radio waves travels the farthest in our universe. When we first started detecting it, it completely changed the idea about many things we knew at the time. For example Active galaxy. we had no idea about the radio jets that the centre of the galaxy emits which completely explained the energy radiation due to accretion disk around the nucleous. Radio waves which requires radio telescopes to be detected as the oldest thing that exist in present universe we live in.

3. Chrlie's point is more convincing as we know that Star formation occurs in the spiral arms because the gas clouds are compressed densy in the arms to form stars. The very luminous, short-lived O and B-stars and H II regions around them enhance the spiral outline. Some stars like O and B live very short and they die out within the spiral before they come out. so, their formation as well as death, both happens in the spiral itself.

1.