how can planetary nebula be identified? select the two correct answers.

Question

dark area
spherical shape
central star remnant
diffuse edges

Answer 1

The correct answers are:

1. Spherical shape: Planetary nebulae often have a round or spherical shape, which is due to the outward expansion of gas and dust ejected by the dying star at their center.

2. Diffuse edges: Planetary nebulae have a diffuse appearance with edges that appear faint and blurred. This is because the expanding gas and dust disperses and mixes with the surrounding interstellar medium, creating a less defined boundary.