When we talk about star death, we’re not really talking about death. We’re talking about the end of a functioning star. Astronomers tend to personify cosmic objects like stars, saying that they are born and die, when it’s more like they transition into something new.
With stars in particular, there’s two main courses their “life cycles,” such that they are, can take: one for massive stars and one for low-mass stars.
We can further subdivide low-mass star “deaths” into those of red dwarfs—like our nearest stellar neighbor, Proxima Centauri—and those of medium-mass stars, like the sun.
But before we dive into the final stages of these stellar life cycles, let’s review what kinds of stars we’re talking about here…
Welcome to my second “Science Answers” post! About a month ago, I sent out a post requesting science questions from all of you; you can find it here. This post addresses the second of the questions I was asked. If you have a question, you can ask it in the comments here or on that post, or ask it in an email. Or find me on Facebook!
Wow…great question. This is a question the greatest scientific minds have asked and tried to answer for centuries. It’s a question not even Stephen Hawking, the scientific genius of the century, has fully answered.
There are a few parts to the gravity question, and they have each been addressed one by one over time:
How does gravity work?
What is gravity?
Why does gravity work?
Isaac Newton stood on the shoulders of the giants before him—Aristotle, Ptolemy, Copernicus, and Kepler—and figured out how gravity works. But he was at a loss to explain what exactly this mysterious force was.
Einstein built on Newton’s work and came up with a theory for what gravity is—that is, distortions in space-time.
We have yet to understand why gravity works. Why is space-time warped? Why do objects distort it as if it were the material of a trampoline? What exactly is the nature of space?
But, lucky for me, the question above specifically asks what gravity is. And that, I can explain.
The best way to do that is to turn one of gravity’s oldest tricks, one that has perplexed scientists and philosophers for thousands of years: What makes the planets move?
Have you ever looked up at the night sky and noticed that while relatively bright stars outline the constellations, there are numerous other stars that are almost too faint to see with the naked eye?
If you ever noticed this, you probably guessed that the brighter stars are literally brighter, and the fainter stars truly are fainter. Or maybe you guessed that they don’t vary in brightness that much, but fainter stars are much farther away.
But that’s not really true…or, at least, it’s not the whole answer.
So what’s the real reason why some stars appear to be brighter than others—and how can we tell how bright they really are?