Most people know what a supernova is, it is simply an explosion when a star collapses and ejects material from its crust into space, but few people know what a type Ia supernova is and why it is used as a standard candle. With what I know, I would like to present it to you in the most concise and understandable way.
First understand what the concept of a standard candlestick is. The standard candle is a fixed measure of the luminosity of supernovae, based on a standard luminosity so that when measuring the luminosity of different Ia supernovae, we can know how many times it is closer or farther than the supernova defined as the other standard candle. The lower the brightness, the further away the supernova is, which is easy to understand.
Type Ia supernovae are neutron stars that eat away material from a companion star, which continues to eat until its mass exceeds the Chandrasekhar realm by about 1.4 times Mo. When the white dwarf exceeds this limit, it becomes too massive and collapses farther in the center, causing a massive explosion. The white dwarf’s carbon atoms frantically participate in a nuclear reaction that explodes with an energy of approximately 1-2.10^44 J tearing apart the star. Reading this far, we can answer the question of why supernova Ia was chosen as a landmark, right? Because that’s a mass limit for this star to explode, that’s the Chandrasekhar limit. Any star that wants to explode in an Ia pattern must accumulate matter to reach 1.4 times the mass of Mo before it can explode. Thus, the conditions for supernova Ia to occur are the same everywhere, so its true luminosity is almost fixed. This is why it is used as a standard candle.
By expanding a little, if the stars have a companion, it is normal for them to explode twice. Once, because they burned all their fuel, they collapsed in the center to create a white dwarf or neutron, and the second time they ate the material from the unfortunate companion star to explode again.
Hoang Quoc Phuong- AT
