ALL ABOUT STARSALL ABOUT STARSBy Prof. Liwayway Memije-Cruz

The Galaxy contains the stars, interstellar media clouds of dust and gases and remnants. It contains primarily the star clusters and interstellar clouds.

The star’s life cycle is somewhat complex where it will take million of years ago before they could proceed to another life stages. All stars originated from clouds of dusts and gases which are commonly referred as nebulae.

Nuclear Fusion Stars are giant nuclear reactors. In the center of stars, atoms are taken apart by tremendous atomic collisions that alter the atomic structure and release an enormous amount of energy. This makes stars hot and bright. is an atomic reaction that fuels stars. In fusion, many nuclei combine together to make a larger one. The result of this process is the release of a lot of energy 

Nuclear Fusion and NucleosynthesisStars are giant nuclear reactors. In the center of stars, atoms are taken apart by tremendous atomic collisions that alter the atomic structure and release an enormous amount of energy. This makes stars hot and bright.

It is in the process of the nuclear fusion that powers a star for the most of its life. The star like our sun undergo changes where it first attain the red giant phase and after which its core collapses into a dense white dwarf that will soon expel planetary nebula in its outer layers. Star similar to our Sun gradually grow in size until they reach a red giant phase after which the core collapses into a dense which dwarf and the outer layers are expelled as a planetary nebula. The life cycle of a sun like star is illustrated in figure 3.1. Oftentimes, much larger stars can explode in a supernova as their cores collapse forming an extremely dense neutron star or the commonly known black hole. Because of extremely long life span, it is not clear how red dwarf die but it may manifest gradual death overtime when its outer layers are expelled out. Moreover, stars have varying luminosity based on the surface temperature.

Parts of the Sun

The sun includes the photosphere, chromosphere, and corona. An extremely hot outermost layer extending outward from the chromosphere several million mile or kilometers, we will see that all of the major features of the sun can be explained by the nuclear reactions that make its energy, the magnetic fields that are caused by the movements of the gas, and the immense gravity.

The death of a giant star results to the formation of a black hole where the mass is contained in a single point. The point at the center is referred to as singularity and the distance from the singularity exhibits a very strong gravitational pull that not even light can pass through. The distance from singularity is known as event horizon. It should be noted that event of horizon is not a boundary but it only means that whatever materials cross it, no way for such to go back or return. Many people might ask what is the size of the black hole? No one could ever measure its size but one thing is certain – when we talk about its size we are referring to the size of event horizon.

Neutron stars are very dense and spin very fast and are typically only 10-15 km in radius. Because neutron stars form from burnt-out stars, they do not glow. The collapses of the star causes the matter to be converted into mostly neutrons, hence the name neutron star

Neutron Star, Pulsar and Black Hole

Dark matter is a body that neither emits nor scatters the light. Most of the matter found in space is believed to constitute 80% of it and 20% energy from its total mass.The existence of dark matter was first postulated by Fritz Zwicky in 1933 to account for evidence of “missing mass” in the orbital velocities of galaxies in clusters. From the consolidation of investigations among the experts, it is hypothesized to be composed of a new subatomic particle.