Transcript: The physical state inside a white dwarf is extraordinary. The density is in the range of 108 to 1011 kilograms per cubic meter. A teaspoon of white dwarf material brought back to the Earth would weigh as much as an elephant. At these densities and temperatures electrons move nearly at the speed of light, and matter no longer behaves as a perfect gas. In fact, it’s a new state of matter called degenerate matter. The atomic nuclei essentially form a lattice with the...

Transcript: The theory of white dwarfs was first worked out by Subrahmanyan Chandrasekhar. Born in India, Chandra, as he was universally known, began thinking about white dwarfs on a long boat voyage to college in England. He experienced prejudice many times in his life, but nothing was more hurtful to him than the scorn that senior astronomers poured on his idea of how white dwarfs worked. But he persevered, and he was proved correct. He was a brilliant theorist, the father to a whole...

Transcript: For stars that begin their lives in the range of a tenth times the mass of the Sun to a few times the mass of the Sun the temperature in the core will never be sufficient to create elements beyond carbon in the periodic table. Eventually the fuel supply is exhausted, and without pressure support the core of these stars must collapse and produce the state of an exceptionally dense star called a white dwarf. The temperature of white dwarfs ranges mostly from 10 to 20 thousand...

Transcript: In 1844 German astronomer Friedrich Bessel studied the motions of Sirius, the brightest star in the sky, and found that it was being tugged by an invisible companion. The companion was eventually detected in 1915 in the glare of Sirius, and it was far too dim to have properties that placed it on the main sequence. It was hotter and much less luminous than the Sun. In terms of its properties, its surface must not be much larger than the surface area of the Earth. This entirely...

Transcript: Every star in the night sky will one day exhaust its nuclear fuel and die. A battle rages within the heart of every star between the inward force of gravity and the outward pressure caused by energy release from nuclear reactions. This is a battle that gravity will always win in the end, and the mode of a star’s death depends, as its life does, on its mass. Low mass stars will die by having their material entombed in a cooling ember, and high mass stars will die in a last...

Transcript: The heaviest elements are fantastically rare compared to hydrogen and helium because they can only be produced in massive stars which are far less numerous than stars like the Sun. But what does it mean to say that gold is a trillion times less abundant than hydrogen? Imagine the analogy of a deck of cards. One in twelve atoms is a helium atom. So the deck would have its aces as helium atoms, and all the other cards would be hydrogen atoms. Oxygen has an abundance of one part...

Transcript: The cosmic abundance of different elements in the periodic table is a fundamental property of the universe that astronomers have successfully explained. The most abundant elements, hydrogen and helium, three quarters hydrogen and one quarter helium by mass, can only be explained when we understand the big bang. Helium was created in the first few minutes of the universe itself. Almost all the heavier elements come from nucleosynthesis within stars. The features of a graph of...

Transcript: The iron at the center of a massive evolved star is not the familiar metal that we are used to, even though the density is very high. The temperature is also high, a billion Kelvin or more, so the iron is a high temperature gas or plasma. Iron is the most stable element, so energy is consumed to make elements more massive than iron. Thus, the heart of a massive star is an iron tomb. There are, however, two ways in which elements heavier than iron can be produced. Helium...

Transcript: In the most massive evolved stars, the star has an onion skin layering where heavier and heavier elements are concentrated in layers closer and closer to the core because the temperature and pressure continue to increase moving towards the center of the star. For example, in a fifteen solar mass star the outermost layers will be filled with a cosmic mixture of three-quarters hydrogen, one-quarter helium by mass. The inner four solar masses will be helium at a temperature of...

Transcript: Evolved massive stars have sufficient pressure and gravity that the temperatures in their cores can cause heavy element creation beyond carbon. Consider the progress of a set of stars; one of 4, one of 6, one of 8, one of 10, and one of 12 solar masses. In the 4 to 6 solar mass stars, in their helium rich cores carbon can be produced by the triple alpha process. In the 8 solar mass stars a set of reactions beyond carbon can continue because the temperatures are about 500...

Transcript: Producing heavy elements by the fusion process requires extreme temperatures. This is because of the electrical force of repulsion that operates between protons. Forcing two protons to combine is four times easier than forcing two helium nuclei to combine, and so on up the fusion chain higher and higher temperatures are required to make heavy elements. In low mass stars, less than about one and a half times the mass of the Sun, the temperature in the core never exceeds the...

Transcript: Where did the heavy elements come from? They were not present at the big bang, the birth of the universe. Stars are the cauldrons that have produced the calcium in our bones, the nitrogen and oxygen in the air we breathe, the metals in the cars we drive, and the silicon in our computers. The story of the creation of heavy elements was first worked out in the 1950s by four young astrophysicists working at the California Institute of Technology. They were the husband and wife...