69089
The ejected outer layers will form what is known as a planetary nebula , returning some of the material that formed the Sun - but now enriched with heavier elements like carbon - to the interstellar medium .
 planetary nebula
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 planetary nebula