Astro2110 – The Solar System

Pauli Exclusion Principle (Wikipedia): every electron is indistinguishable from another. Two identical electrons cannot locate in the same volume of space with the same exact properties (energy, spin, direction) Thus, the electron has to be excluded from this space or remain at the higher energy level. 

When a main-sequence star (Wikipedia) comes towards the end of its life, the pressure at its core is so high that all electron states are filled. Therefore, electrons become degenerate (Wikipedia) they are forced to have higher energy than they should have at their temperatures due to Pauli Exclusion Principle. Therefore, its He core collapses, and stars climb to the red giant branch until the core temperature reaches 10^8K, then He fusion begins in the core (helium will become carbon). This process occurs at the top of the red giant branch. Moreover, the star’s core volume will be bigger due to He fusion, so there will no longer be any electron degeneracy, all energy restored due to degeneracy will be released at one, causing Helium Flash (Wikipedia)

Therefore, the star will drop to a horizontal branch and becomes a red supergiant. The carbon core will slowly collapse and the H&He burning shall overcome gravity. Dust forms in outer space, light energy pushes out dust, and dust pushes gas, the outer envelope will slowly be blown away, forming a Planetary nebula (Wikipedia).

The collapsing carbon core henceforth becomes White Dwarf (Wikipedia). Whit dwarves have balance between gravity and degeneracy and are very dense. They cannot shrink anymore. They will cool off eventually. 

Pluto, formerly considered one of the nine planets, has always been controversial. Nonetheless, since the International Astronomical Union redefined the meaning of planet (A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit) (check IAU Website for further information)

Pluto now falls into the category of a dwarf planet because of its size and the fact that it inhabits a region of other similarly sized bodies known as the Trans-Neptunian region. A dwarf planet is a celestial body that -orbits the sun, has enough mass to assume a nearly round shape, has not cleared the neighborhood around its orbit and is not a moon.

NASA’s New Horizons mission is the first mission that conducted a Pluto flyby and provided humans with a high resolute picture of Pluto. 

Pluto has one important moon: Charon. Half the size of Pluto, Cajun is the largest moon of Pluto and the largest known moon relative to its parent body. Pluto and Charon are considered binary systems and experience tidal locking. NASA’s New Horizons mission discovered that the reddish north cap of Charon is atmospheric outgassing from Pluto. 

Neutron stars are the collapsed core of the massive stars (our Sun cannot qualify that). Neutron star was the smallest and densest stellar object in the universe. A city-sized neutron star can obtain the mass of the Sun. There are two types of neutron stars — magnetars and pulsars. Pulsars are neutron stars with fast rotational rates, and magnetars — as the name states — are neutron stars with extremely large magnetic fields. Magnetar — my favorite object in the whole universe —  formed from a fascinating process. During the formation when the supernova explosion happened, the magnetic field increases due to the conservation of magnetic flux. Strong magnetic fields originated from magnetar originated from the magnetohydrodynamic dynamo process before neutron stars reached equilibrium configuration. Through the dynamo process, heat and rotational energy will convert into magnetic energy. Strong magnetic fields exist and persist because of the currents in a proton-superconductor phase of matter. Giant flares, the strong eruptions caused by magnetars, burst gamma rays and give enormous information & interesting phenomenon about this mysterious star.