What does stardust mean? From the perspective of the universe, are we made of stardust?

We are all made of stardust? This statement seems a bit outrageous. However, the famous astronomer carl sagan Gen explained that elements heavier than lithium could not be synthesized without a violent supernova explosion. Therefore, there would be no planets and we would not exist.

Superstars in the early universe will suddenly explode into supernovae later in their lives. They are hot and big enough to produce new elements by themselves. When a star is blown to pieces, a huge explosion will produce new chemical elements and spread them into space.

The chemistry of life also began at this time. Hydrogen was born in the Big Bang, but without oxygen from the stars, there would be no water. Our bodies are almost entirely made up of water (depending on your calculation method), and almost all the life we know depends on water. Hydrogen from the star combines with oxygen produced by the star, and after billions of years, it becomes a part of the cytoplasm of your epidermal cells.

The second generation star is formed by the fragments of the first generation star, not all of which are huge and easy to burn out; Many of them are still alive today. The larger of these stars is also short-lived, and will also end in the form of supernovae, and spread more elements into the universe. The iron in hemoglobin in your blood is formed in such an explosion.

Supernovae are not the only way for dying stars to diffuse chemical elements. The thin atmosphere of a dying star is hardly bound by gravity. When they pulse, a lot of gas will disappear in the form of star wind. For the sun, it is the solar wind. Fortunately for us, its life is very peaceful. The farther away from the star, the lower the ambient temperature, so atoms can combine into molecules: methane and carbon dioxide, both of which are necessary for life.

Betelgeuse, the bright red star that constitutes Orion's shoulder, is such a dying star. Observations by the Very Large Telescope (VLT) in Chile show that Betelgeuse is surrounded by a huge ejection cloud, which is about 2 billion kilometers wide and contains oxygen-rich molecules, especially silica, the main component of the beach. A silicon atom that makes up the aorta in your body is blown into space by the star wind.

The "coat" around the core of a star is not high enough to synthesize atoms, but it plays different roles in nuclear reactions. Neutrons from the star's core bombard atoms in the outer layer of the star, producing heavier elements that can be carried away by the wind of the star. Technetium (meaning "man-made") is an unstable rare element, which cannot be naturally produced on the earth, but is produced in the "coat" of a superstar. Calcium in your teeth and baby milk powder is also produced in this way.

Low-mass stars cannot end their lives by explosion, and their outer layers will gradually lose and form planetary nebulae. These planetary nebulae can spread various elements and organic molecules in space. This includes amino acids, which are the basic materials that make up the protein of you and all other living things. Other ways of death of stars, such as the explosion of white dwarfs or the collision of pulsars, will also produce some atoms.

The sun, a star with planets and life, is neither the first generation nor the second generation. Our solar system was born in a star graveyard, where at least one star was buried. There is enough iron and nickel to form the earth, the moon and other rocky planets. In fact, researchers have discovered two silica meteorites-incredibly small-which contain oxygen isotopes that are not formed in the stellar atmosphere, but are consistent with the products of supernovae.

No matter where the source is, through the fusion of dying stars and other forms of nuclear reactions, products are sent into space through stellar winds and explosions. Almost all the elements that can be found on the earth and brought into space by humans are provided by stars.