Stars also have a life cycle and die after the cessation of their thermonuclear activity, which generates an explosion of their mass into interstellar space; in this final stage the star is called a supernova.


What is a supernova?

Supernovae are stellar explosions that occur at the end of a star’s life. This releases large amounts of energy, heavy materials , dust and gas, a product of the depletion of nuclear fuel that leads to the cessation of thermonuclear reactions.



A supernova is a stellar explosion that releases heavy elements, dust, and gas. This process occurs at the end of a star’s life.



  • The explosions of supernovae reach speeds from 15,000 to 40,000 kilometers per second .
  • The luminosity of its explosion lasts for days or months .
  • During the explosion, some spectral lines of hydrogen emanate .
  • Their luminosity depends on the metals they contain.
  • They can trigger the formation of nebulae .


  • Type I supernovae: do not emanate hydrogen lines during the evolution of their brightness.
    • Type Ia: when its brightness is at its maximum, silicon absorption lines emanate and then iron and cobalt lines .
    • Type Ib: very weak neutral helium lines emanate , which are not visible at first.
    • Type Ic: they do not show lines of SiII or neutral helium , however, elements of intermediate masses emanate.
  • Type II supernovae: show hydrogen spectral lines for long periods of time. The light curves of this type of supernovae are highly varied and peak rapidly. According to the light curve, they are divided into:
    • Type II-L: the drop in brightness after its maximum occurs in an accelerated manner.
    • Type II-P: Its light curves constantly maintain their brightness during explosions and after reaching the maximum, the brightness decays in months.

How it is formed

Supernovae are formed when a star dies , although not all stars can become supernovae, it is giant stars that can.

The first theory on the formation of supernovae explains that the process begins when, due to lack of fuel in the nucleus , thermonuclear reactions  cease to be generated . This leads to the pressure of the nucleus decreasing and the nucleus contracting abruptly, heating up and collapsing , emanating energy.

Another theory talks about binary star systems , this is a more violent process and it happens when a white dwarf receives mass from its companion , this mass must help to exceed the Chandrasekhar limit . This generates an internal compression that triggers the thermonuclear reactions and explodes the white dwarf , which usually takes its sister ahead ; there are rarely remains of his companion.

Explosion of a supernova

The explosion of a supernova generated by the depletion of fuel in its core, generates the cessation of its gravity and the irradiation of stellar debris composed of heavy elements, dust and gas.

What temperature can it reach

The temperature of supernovae varies depending on their mass and the energy of their nucleus. A typical type II supernova can reach 100 billion degrees Celsius and when its core collapses it can reach three billion degrees. Supernova 1987A reached 48 billion degrees Celsius and was the hottest object measured in the universe.

Examples of supernova

  • RCW 86 – Observed by the Chinese in 185 AD.
  • SN 1006: It is a bright and ancient supernova, dating back to the year 1006, records were found in Egypt, Japan , Switzerland, Iraq, Italy and China .
  • SN 1054: This nebula formed the Crab Nebula .
  • Tycho remnant supernova or SN 1572: It was observed by Europeans, Chinese and Koreans in AD 1572.
  • Kepler’s supernova or SN 1604: observed in AD 1,604 by Europeans, Chinese and Koreans.
  • SN 1604: It is the last supernova seen in the Milky Way .
  • Supernova 1987A: observed hours after its explosion and advanced modern theories about the formation of supernovae.
  • Supernova in Cassiopeia: it exploded approximately 300 years ago, it was not observed from Earth, but its age is estimated by the remnants of its explosion, which caused the brightest by its radio band.
  • 2005ap: is the brightest observed supernova.
  • SN 2006gy: it is the second largest that has been observed.


The importance of supernovae is that they have contributed heavy materials to the interstellar medium, which is essential for the formation and evolution of planets and living beings.

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