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Protoclusters are galaxy clusters that are at a very high redshift. Redshift is the lengthening of wavelengths of spectral lines due to the doppler effect. In particular the radial motion of the radiation source from the observer. These galaxies are grouped together in an area where relatively few galaxies are known. They are presumed to be relatively young stars, this is where the name comes from.
Brown Dwarfs tick off a halfway point between stars and planets. They usually have 75 times the mass of Jupiter but are not able to produce stable luminosity. This is because they cannot though the thermonuclear fusion of hydrogen like in a regular star. They fuse elements but get to a point where their cores hold up through electron degeneracy pressure. The dwarfs are called brown though they have a deep red to magenta colour relative to their temperature.
Low mass stars are stars with the masses less than half the mass of our Sun. They are the smallest, coolest, and dimmest in the main group of Stars. They can be orange, red, or brown in colour because of this. They use up their hydrogen very slowly which leads them to having very long lives. They die by burning up their fuel
Massive Stars are larger than eight solar masses during its regular lifetime. They have a quick main sequence phase. At this time there is a balance between the force of gravity inwards and the nuclear fusion at the core outwards. This continues until the elements usually hydrogen in the core runs out. They usually last few trillion years.
Black Dwarfs are currently theoretical objects that remain after a White Dwarf has used up all its fuel and cooled off to an extremely dense cold carbon ball. These stars only occur in nature if the white dwarf star is on its own. On the other hand if the White Dwarf is close to another one, they can collide together forming a Neutron Star or a Black hole. They have never been observed by humans due to their colour and time it takes to die.
Red Giants are stars with high luminosity and low surface temperature. These stars are found near the end of a stars life cycle when the nuclear fusion starts to slow down due to the lack of elements inside of the star. These stars usually swell up to many times the size of their original self, and start to burn Carbon. After this whole process they end up shrinking down losing its energy.
White Dwarfs come after Red Dwarfs and mark the final stage in a stars life cycle before it becomes a Black Dwarf. They are the hot dense remnants of dead stars, and are born when a star shuts down. The balance between nuclear fusion and gravity is steady. They are born after the deaths of Red Dwarfs when it evaporates, leaving the core, or White Dwarf exposed.
Wolf-Rayet Stars are in the later portion of their life cycle, losing mass at a very rapid pace. They usually have masses that are over 25 times than the sun and have very brief lifetimes. We currently know about 200 in our solar system, but due to the dust around the Milky Way, scientists predict there are about 1 to 2 thousand hidden. Their at temperatures of around 25,000 K which means their luminosity can be over a million times more than our Suns.
A Pair Instability Remnant or a Pulsational Pair Instability Supernova is a fake supernova in summarized terms. They occur in stars with the mass of 100 to 130 solar masses are caused by draining of a star's energy in the process of electron positron pairs. There are multiple examples of these in the past 200 years but no one knows for sure.
A Type II Supernova explosion is known as a classic type of supernova, it occurs within stars that have at least 8 solar masses at the end of its lifetime. Supernovae are explosions of materials after the deaths of stars that meet the specific conditions. They occur when the gravitational force of the star overcomes the nuclear fusion at its center.
Supernova remnants are the remnants of a supernova. Relatively easy to figure out from the name, there are different types of remnants being, shell type, crab-like, composite remains, thermal composites, and plerionic remnants. We can measure a remnants age using the formula of rate x time = distance. so if we found a remnant that expanded at 5% of 20 years we found the rate to be 0.25, multiply it by the distance, and we'd be given the time.
As described by NASA a black hole is place in space that has a gravitational pull so strong that not even light can escape. Because of this it's not actually possible to see these celestial bodies with our actual eyes. In the centre of a blackhole there is an infinitely small and dense point called a singularity. Fun fact when reversing the equation for a blackhole you can get a white hole. None have ever been seen but are mathematically possible.
A Neutron star comes from the collapsed core of a supermassive giant star. Apart from blackholes, neutron stars are known to be one of the smallest and densest stellar objects. When they form they are extremely hot and cool down after. These stellar objects are formed with a diameter of about 20 km, and mass from 1.5 to 2 times the sun.
Among one of the most odd objects in the universe, pulsars are like neutron stars but they spin at a very fast pace. It's a highly compact core after a supernova explosion that has a very strong magnetic field. Most neutron stars have magnetic fields of about one trillion times the magnitude of Earths magnetic field. They emit very powerful gamma rays pulsars that can be harmful to spaceships and other objects as explored in the previous section.
Loosely bound groups of hundreds of stars together. They are of interest to astronomers because they all formed during the same time period. About 1100 clusters have been found within the Milky Way. Star cluster studies have been important when working out how stars evolve, the power of the Hubble telescope is the main resource when studying them. It has the power to look beyond the Milky Way and out into the Local Group of neighbouring galaxies.
