When Stars Die Trivia Quiz

Answer: Sequence

After its initial formation from a giant nebula of gas, nuclear fusion begins in the star's core. The energy from the heat that this creates balances the pressure from its gravity and keeps it from collapsing. In this state of equilibrium, the star will begin to burn steadily, for a few million years in the case of the most massive stars to around 10 billion years in the case of a relatively small star such as our sun. This long period of equilibrium is called the main sequence.

As the star eventually uses up all its fuel, the equilibrium is lost, the star moves off the main sequence, and the fireworks begin.

Answer: Hydrogen

With a single proton and electron, hydrogen atoms are by far the most common element in the universe and make up the bulk of the star's mass. The immense pressure of this mass forces the hydrogen atoms together to form helium, element number 2 on your table, with two protons and two electrons.

Answer: Element number 26 - Iron

The pressure in our sun's core will be enough to convert helium into carbon. The sun is not massive enough, however, to continue the process and begin converting the carbon itself. High-mass stars, on the other hand, will proceed to convert their new stocks of carbon into neon. Once all the carbon has been converted to neon, they will begin converting the neon to oxygen. Next, oxygen will be converted to silicon. Then, the star will begin converting silicon to iron.

Unfortunately for the star, the "binding energy" that holds an iron atom together is particularly strong. This makes it impossible for the star, no matter how massive, to convert the iron into anything else. Instead of supplying a new stock of "fuel", therefore, the iron begins to build up in the core, leaving the star with a dead heart that it cannot burn.

Answer: True

When all the hydrogen in the core has been converted to helium, the star will begin to burn the hydrogen in its atmosphere. With the source of its heat moving outwards, the star will expand. A very small star will do so for a short time before beginning to fade until it becomes a black dwarf. A star the size of our sun will continue to expand until it becomes a red giant. Any humans still inhabiting Earth at this point would be wise to make evacuation plans.

Stars with very high mass will continue to expand until they become supergiants - stars so big that they defy imagination. Some of these monsters, if hypothetically placed where our sun sits now, would extend out to the orbit of the planet Saturn.

Answer: The Chandrasekhar limit

Named after Subrahmanyan Chandrasekhar, the astrophysicist who discovered it, the 1.4 solar-mass limit is a crucial tool for predicting the fate of a dying star. While the star's future after it collapses depends on its mass, it is not possible to accurately predict its future from the mass of the original star. This is because the star loses an unpredictable amount of matter during the phase when it expands. A huge star, with a lot of mass, may lose vast quantities of matter as it expands. When it collapses to a stellar remnant, therefore, the remnant may be quite small.

The mass of the stellar remnant itself, however, can be used to predict the star's fate precisely. If it is less than 1.4 solar masses, the remnant will remain ordinary matter. If it is more than 1.4 solar masses, the remnant's gravity will cause it to collapse even further - and the results are anything but ordinary!

Answer: A white dwarf

After their red-giant phase, small stars such as our sun will collapse to stellar remnants whose mass is below the Chandrasekhar limit of 1.4 solar masses. These stars will finish not with a bang, but with a whimper. Their gravity will not be strong enough to collapse them any further and they will settle into a new equilibrium as "white dwarfs". Gradually, over a period lasting hundreds of millions of years, they will fade away.

That's not to say that a white dwarf's gravity is "weak", however. These stellar corpses are extremely compact and dense. A white dwarf is squeezed into a sphere roughly the size of Earth. However, it contains as much mass as the sun, and its gravity is therefore a million times stronger than Earth's.

Answer: Supernova

As massive stars convert more and more silicon into iron, which they cannot burn, the iron builds up in their core. Eventually, the mass of the iron in the core reaches the Chandrasekhar limit of 1.4 solar masses and its internal pressure can no longer balance against the crushing pressure of its gravity. The iron core suddenly collapses into a small, unimaginably dense object.

As the core implodes, the outer layers of the supergiant star implode with it. When these outer layers hit the compressed, rigid core, they are repelled back into space at speeds of around 45 million miles per hour. Vast amounts of energy are released in a supernova, making it incredibly luminous. The most recent supernova recorded by observers on Earth, in 1604, took place 20,000 light years from us, but was so bright that it was visible in daylight.

Answer: A neutron star

An ordinary atom consists of a nucleus (made up of protons and neutrons) surrounded by electrons. Although the nucleus is extremely compact and dense, the atom itself is not. Between the nucleus and the electrons is a comparatively large area of empty space. When the iron core of a star collapses in a supernova, however, it is crushed down into an object consisting entirely of neutrons. These neutrons are packed so tightly together that the object, although it is the size of an average city, has the density of an atomic nucleus! A neutron star is a billion times denser than a white dwarf.

Should you ever happen to notice a neutron star in your vicinity, you are advised to quickly head the other way. The star is so dense that its gravity is a trillion times stronger than the gravity you are used to on Earth. If you were standing on its surface, you would be squashed. Even if you were cool with the gravity, you'd have to think about the neutron star's magnetic field, which is several trillion times stronger than Earth's. A magnetic field like this would stretch your atoms into cylindrical shapes. Thinking about this stuff freaks me out, man!

Answer: A black hole

If the collapsing iron core has more than 3 solar masses, it will not even be able to survive as neutrons. Its gravity will continue to compress it until it becomes a single point, known as a "singularity". Have you ever wondered how "big" a black hole is? The answer is that it does not have any size at all. From the point of view of an outside observer, the singularity is a point that has zero volume. And yet, within that point, it contains as much mass as three stars the size of our sun.

Matter that has been compressed to this kind of unimaginable density produces gravity so strong that within a certain distance of it, called the "event horizon", nothing can escape. "Escape velocity" is the speed something needs to go to escape an object's gravity. For example, a rocket needs to go at around 25,000 miles per hour to break free of Earth's gravity. Within the event horizon of a black hole, the escape velocity is the speed of light. Since nothing can go faster than the speed of light, nothing can ever, ever escape from within the event horizon. Thinking about this stuff freaks me out even more, man!

Answer: Population I stars are young stars; Population II stars are stars from the early universe

The early universe did not contain most of the elements on the periodic table. Its earliest stars, the Population II stars, contained only hydrogen and helium. When a star like this died long ago, the extreme effects of the supernova created the heavier elements. The gas from the supernova then collapsed to form new Population I stars, such as our sun. This is why heavy elements, such as gold for example, exist in our solar system.

All the matter that makes up the planets in our solar system was once part of a Population II star. This means that every single atom in your body once blazed with light inside the inferno of a giant star that died billions of years ago. This will be a helpful thing to keep in mind next time you ask someone out on a date, get rejected, and need to restore your self-esteem by making yourself feel a little bit special.