The Supernova
Phenomenon
Stars are the most widely recognized astronomical objects and represent the most
fundamental building blocks of galaxies. Ever since mankind first became able to comprehend our
existence, we have looked up at the night sky and observed these distant glimmers of light which
have continually shaped our culture, religion, and scientific progress. While only a handful of stars
are visible with the naked eye amidst the current era’s light pollution, the universe holds more
stars than one could possibly imagine shining and radiating light and heat throughout entire
galaxies. They provide the essential warmth that cradles life. Stars are massive spheres of matter in
plasma state held together by their own gravity which are for the vast majority of their lives
powered by nuclear fusion. There are estimated to be as many as 300 sextillion stars in the visible
universe.
Stars, albeit not living like us, also go through phases of evolution. Stellar
evolution, encompassing the entire life cycle of stars from birth to death and every stage in
between, spans millions (for the most massive stars) to trillions of years (for the least
massive) which is considerably longer than the age of the universe. Therefore, stars do not seem
to change at all for us, because a human lifetime is a snippet of a fraction of a blink of an eye to
these behemoths. The path that will be followed by a particular star depends primarily on its mass.
Life cycle of stars can be broken down into four main stages:
Star Formation:
1. Molecular Cloud
Star formation begins with molecular clouds, a type of nebulae which are cool, dense interstellar
regions of dust and atoms, that have been around since the earliest days of the universe containing
1
, higher densities than their surrounding space and so are held together by their own gravity. These
clouds consist of mostly Hydrogen (H), the most abundant element in the universe, and usually
about a quarter of Helium (He) with smaller fractions of other heavier elements.
A familiar example of such as a dust cloud is the Orion Nebula (Messier 42), the closest
region of massive star formation to the Earth
found in the constellation of Orion’s sword.
These large clouds come closer and
closer and eventually collapse into a dense
core due to their own gravitational energy. As
the cloud collapses, the gravitational energy
causes it to heat up, and the
conservation of momentum from all the
individual particles causes it to spin.
2. Protostar
When this collapsing cloud reaches a relatively
Figure 1: Orion Nebula
stabler point the embryo of a star forms known
as a Protostar. These infant stars have a circumstellar disk of additional matter some of
which continues to spiral inwards layering additional mass onto the star while trapping more
Hydrogen and Helium within the core. This process of incubation takes about 10 million years.
When the protostar is sufficiently developed, it begins to emit plumes of gas which alongside the
external radiation helps to drive away the gas clouds around the outside, essentially the shell of the
star. These shell gases that are driven away are mostly dust and are ejected outwards but still orbit
the new star. The dust begins to clump together forming rocks and these rocks smash together to
form planetary embryos which have the potential to form planets.
3. Main Sequence
Eventually, the core temperature of a star will reach the point that fusion its core can begin causing
the initiation of the third stage, the main sequence. This phase is the longest in the life cycle of a
massive star, often continuing for millions to billions of years. It accounts for about 90% of a
star’s lifespan and is the point when thermonuclear fusion begins to take place with the vast
2
Phenomenon
Stars are the most widely recognized astronomical objects and represent the most
fundamental building blocks of galaxies. Ever since mankind first became able to comprehend our
existence, we have looked up at the night sky and observed these distant glimmers of light which
have continually shaped our culture, religion, and scientific progress. While only a handful of stars
are visible with the naked eye amidst the current era’s light pollution, the universe holds more
stars than one could possibly imagine shining and radiating light and heat throughout entire
galaxies. They provide the essential warmth that cradles life. Stars are massive spheres of matter in
plasma state held together by their own gravity which are for the vast majority of their lives
powered by nuclear fusion. There are estimated to be as many as 300 sextillion stars in the visible
universe.
Stars, albeit not living like us, also go through phases of evolution. Stellar
evolution, encompassing the entire life cycle of stars from birth to death and every stage in
between, spans millions (for the most massive stars) to trillions of years (for the least
massive) which is considerably longer than the age of the universe. Therefore, stars do not seem
to change at all for us, because a human lifetime is a snippet of a fraction of a blink of an eye to
these behemoths. The path that will be followed by a particular star depends primarily on its mass.
Life cycle of stars can be broken down into four main stages:
Star Formation:
1. Molecular Cloud
Star formation begins with molecular clouds, a type of nebulae which are cool, dense interstellar
regions of dust and atoms, that have been around since the earliest days of the universe containing
1
, higher densities than their surrounding space and so are held together by their own gravity. These
clouds consist of mostly Hydrogen (H), the most abundant element in the universe, and usually
about a quarter of Helium (He) with smaller fractions of other heavier elements.
A familiar example of such as a dust cloud is the Orion Nebula (Messier 42), the closest
region of massive star formation to the Earth
found in the constellation of Orion’s sword.
These large clouds come closer and
closer and eventually collapse into a dense
core due to their own gravitational energy. As
the cloud collapses, the gravitational energy
causes it to heat up, and the
conservation of momentum from all the
individual particles causes it to spin.
2. Protostar
When this collapsing cloud reaches a relatively
Figure 1: Orion Nebula
stabler point the embryo of a star forms known
as a Protostar. These infant stars have a circumstellar disk of additional matter some of
which continues to spiral inwards layering additional mass onto the star while trapping more
Hydrogen and Helium within the core. This process of incubation takes about 10 million years.
When the protostar is sufficiently developed, it begins to emit plumes of gas which alongside the
external radiation helps to drive away the gas clouds around the outside, essentially the shell of the
star. These shell gases that are driven away are mostly dust and are ejected outwards but still orbit
the new star. The dust begins to clump together forming rocks and these rocks smash together to
form planetary embryos which have the potential to form planets.
3. Main Sequence
Eventually, the core temperature of a star will reach the point that fusion its core can begin causing
the initiation of the third stage, the main sequence. This phase is the longest in the life cycle of a
massive star, often continuing for millions to billions of years. It accounts for about 90% of a
star’s lifespan and is the point when thermonuclear fusion begins to take place with the vast
2
