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Red Giant
A late evolutionary stage of a medium-mass star where the outer layers expand and cool after hydrogen fusion in the core ceases. Red giants can eventually shed their outer envelopes, forming planetary nebulae.
Source: esa.int
APODs including "Red Giant"
Nebulae For Christmas
25/12/1998
Image Credit: NASA Astronomy Picture of the Day
If our Galaxy were a Christmas tree, planetary nebulae would adorn it like colorful lighted ornaments twinkling on a cosmic scale. Glowing shrouds of gas ejected by red giant stars, planetary nebulae like NGC 6578 (left) and IC 3568 last for a mere 10,000 years or so as swollen stellar giants are transformed into fading, cooling white dwarf stars. Meanwhile ... have a safe, happy holiday season and Best Wishes to all from APOD!