Formation of quark stars

April 3, 2003 on 12:01 am | In Ad Rem | 13 Comments

Quark stars are what got me to pursue Astronomy as a hobby. Imagine a star so dense it cannot contain itself, explodes and is now so dense it cannot remain a neutron star. Normally this would form an event horizon and become a singularity. But there is a point of equilibrium between these two states. A star just less than 15 times the mass of our sun has a small chance of shattering the strong forces holding its own matter together, and collapsing into a ball of strange quarks the size of Manhattan. This phenomenon would have a gravitational pull just shy of a black hole, while being more massive, and smaller than a neutron star.

To start the discussion of quark stars I must first explain, in layman’s terms, the process of fusion igniting a star. Most planets are not much more than a collection of hydrogen (H2), the most common element in the universe. Saturn and Jupiter likely began as a relatively small rock, which gravitationally collected immense amounts of hydrogen to form a giant sphere. The deeper into these planets the more dense is the hydrogen.

Moving along to the next phase of gas giants come to the brown dwarf. These are not terribly larger than Jupiter, but can be multiple magnitudes more dense. This greatly increases the gravitational forces on the body, which compresses its core to the point of deuterium (2H2) fusion.

Due to its own gravity a more massive body can begin to press its core so greatly that four hydrogen nuclei fuse to become one helium (He) nucleus. This conversion leaves excess energy, which is expelled during the process. In a star the size of the sun, 2,000,000,000 kilograms of mass becomes energy through fusion every second.

When the mass becomes five times greater than our sun explosions can occur. Fusion process ends, and the mass of the core becomes denser, to the point of becoming completely iron. The outside expands greatly into a supergiant. The core undergoes gravitational collapse and rises to over 100,000,000,000 degrees. The gravity only briefly overcomes the repulsive force of the nuclei and creates a shockwave, blowing off the outer layers of the star. The outer layers smash together fusing into new elements and isotopes. The outer matter continues into space as a nebula. The core remaining is a super massive, but very small ball of neutrons. This neutron star is usually spinning at a very high speed, and has a tremendous amount of electrons, creating a strong magnetic field. This interacting with the expanding remnant creates gamma and x-rays.

What if the star was 15 times our sun or greater? Well the neutrons do not survive the collapse. They break down into an unknown form of matter and forms an event horizon outside of itself. The matter is now a super-massive singularity, a black hole.

As I mentioned up top, quark stars are at an odd state between a black hole and a much larger neutron star. A neutron is a bond between a proton and an electron, which is in a neutral state. 3 quarks make up a proton. When the gravitational collapse occurs, electrons are expelled and trapped as the matter undergoes this transformation to a smaller state. As this transformation ends the quarks can be found in a crystalline structure. It has now reached equilibrium between shattering into a quantum singularity and being a relatively simple ball of neutron.