The disc which contains spiral arms of the galaxy part would be used to study the birth starts in a spiral galaxy
Explanation:
- A galaxy has four parts and they are bulge, disc, spiral arms and halo
- Bulge primarily contains old stars, gas and dust.
- The disc contains the spiral arms also, it is the flattened portion of the spiral arms where we could find most of the young stars, gas and dust. Some old stars are also found in this region
- Spiral arms are only found in spiral galaxies. It is the curved extension begins from the bulge. Here, also you could find young stars, dust and gas.
- Halo is the part where we could find clusters or individual old starts and also the dark matter. The dark matter we can't see but can estimate the gravitational force.
Poor air and water quality, insufficient water availability, waste-disposal problems, and high energy consumption are exacerbated by the increasing population density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world's urban areas swell.
"Shallow‐focus earthquakes occur along transform boundaries where two plates move past each other. The earthquakes originate in the transform fault, or in parallel strike‐slip faults, probably when a frictional resistance in the fault system is overcome and the plates suddenly move."
https://www.cliffsnotes.com/study-guides/geology/earthquakes/earthquakes-and-plate-tectonics
