How can a planetary nebula be identified? Select the two correct answers.(1 point)

A planetary nebula can be identified by the following two characteristics:

1. **Spherical shape** - Planetary nebulae often exhibit a roughly spherical appearance as they expand in all directions.
2. **Central star remnant** - They typically contain a central star remnant, which is a hot core of gas that is often shining brightly as it emits ultraviolet radiation.

So, the correct answers are "spherical shape" and "central star remnant."