how can planetary nebula be identified? select the two correct answers.
dark area
spherical shape
central star remnant
diffuse edges
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.
The correct answers are:
1. Spherical shape: Planetary nebulae often have a roughly spherical shape, appearing like a glowing ball or shell of gas surrounding a central star.
2. Central star remnant: Planetary nebulae are formed from the outer layers of a dying star that has shed its material. The central star remnant, which is often a white dwarf, is typically visible within the planetary nebula.
To identify a planetary nebula, you should look for two correct identifying features.
1. Spherical shape: Planetary nebulae often have a distinctive round or spherical shape. This is because they are formed from the outer layers of a dying star expanding into space.
2. Central star remnant: Planetary nebulae are formed when a dying star sheds its outer layers, leaving behind a hot, dense core known as the central star remnant. The presence of this central star remnant is a key characteristic of a planetary nebula.
Dark areas and diffuse edges, while visually interesting features, are not specific to planetary nebulae and do not necessarily indicate their presence.