The Life of a Star: White Dwarfs and Planetary Nebulae

How do stars become white dwarves and planetary nebulae? Find out on today's episode of Astro Minute!

What is Astro Minute?

Welcome to the Astro Minute! I'm Lauren Smyth, and with the help of astronomer and teacher Kelli Smyth, I'll be your tour guide as we explore the secrets of the night sky sixty seconds at a time.

Welcome to the Astro Minute, where we’re exploring the universe sixty seconds at a time. I’m Lauren Smyth, and today we’re exploring the death of low- and medium-mass stars.

When a lower-mass star leaves the main sequence, it becomes a red giant in its old age. After a time, the red giant becomes unstable and begins to expand and contract, gently shedding its outer layers. What remains is a white dwarf, a small, hot, extremely dense, mostly carbon core. Though no longer undergoing nuclear fusion, the white dwarf is still hot enough to illuminate its shroud of expelled gas in a colorful display called a planetary nebula. If it has no companion star, the white dwarf will in time cool completely and become a black dwarf. Our own sun will follow this path.

White dwarfs cannot be seen naked eye, but under very dark skies you may see the Dumbbell Nebula, a beautiful planetary nebula.

I’m Lauren Smyth, and that’s your AstroMinute.