Question

Where do you expect to find an  O−type star:

*can be multiple options

	Equally likely in a spiral or elliptical galaxy
	On the spiral arms of a spiral galaxy
	In the halo of a spiral galaxy
	Near the center of a small elliptical galaxy
	On the disk of a large elliptical galaxy

Answer 1

An O-type star is a hot, blue-white star of spectral type O which has a temperature of around 30,000 Kelvin. They are heavy stars because of which they end their lives quickly in supernova explosions, resulting in black holes or neutron stars. Therefore this O type  stars are typically expected in regions of active star formation, such as the spiral arms of a spiral galaxy. Since they are short lived they cannot move much after the its formed. Thus  they stay near to the spiral arm in which they formed.

Elliptical galaxies are dim and consist of older, low-mass stars with less star formation activity. Hence it is not likely that O type stars can be found in elliptical galaxy.

Halo of a spiral galaxy is also cooler than the spiral arms which makes it unlikely place for O type star is exist. Also as mentioned above the O type star cannot move far away from the spiral arms where they are formed.

Answer: O-type star is expected to be found on the spiral arms of a spiral galaxy.