The spectra of stars were shown to have distinctive features, which allowed them to be categorized. In the early part of the 20th century, information about the types and distances of stars became more readily available. These are all regions of star formation that contain many hot young stars including several bright stars of spectral type O. Hot and brilliant O-type main-sequence stars in star-forming regions. More massive stars can explode as a supernova, or collapse directly into a black hole. The behavior of a star now depends on its mass, with stars below 0.23 M ☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. In general, the more massive a star is, the shorter its lifespan on the main sequence. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M ☉ undergo convection throughout their mass. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses ( M ☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. ![]() The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. ![]() All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. Īfter a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. Stars on this band are known as main-sequence stars or "dwarf" stars. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. This plot shows 22,000 stars from the Hipparcos Catalogue together with 1,000 low-luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. The main sequence is visible as a prominent diagonal band that runs from the upper left to the lower right. Minor breaks are indicated here for convenience.A Hertzsprung–Russell diagram plots the actual brightness (or absolute magnitude) of a star against its color index (represented as B−V). It is unverified if Axiom Verge 2 does.Ī sequence break occurs when a player do things in an order that differs from the main sequence. ![]() (Players must complete all branches, but can do so in the order they want.) Axiom Verge 1 has no such branches. ![]() Everything listed here is required to complete the game, anything else is considered optional.Ī "branch" occurs when the main sequence offers multiple equally natural choices. The main sequence in a game is the normal (most natural) sequence in which required items are acquired, bosses are fought, characters are met, and major events happen.
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