TYPES OF STAR BIBLICAL
1 CORITHIANS 15:41
41[There is] one glory of the sun, and another glory of the moon, and another glory of the stars: for [one] star differeth from [another] star in glory."
Types of Stars
A star
is a star, right? Well, not exactly. There are many different types of
stars, from the tiny brown dwarfs to the red and blue supergiants. There
are even more bizarre kinds of stars, like neutron stars and Wolf-Rayet
stars. Let’s take a look at all the different types of stars there are.Protostar
A protostar is what you have before a star forms. A protostar is a
collection of gas that has collapsed down from a giant molecular cloud.
The protostar phase of stellar evolution lasts about 100,000 years. Over
time,
gravity and pressure increase, forcing the protostar to collapse down.
All of the energy release by the protostar comes only from the heating
caused by the gravitational energy – nuclear fusion reactions haven’t
started yet.
T Tauri Star
A T Tauri star is stage in a
star’s formation and evolution right before it becomes a main sequence
star. This phase occurs at the end of the protostar phase, when the
gravitational pressure holding the star together is the source of all
its energy. T Tauri stars don’t have enough pressure and temperature at
their cores to generate nuclear fusion, but they do resemble main
sequence stars; they’re about the same temperature but brighter because
they’re a larger. T Tauri stars can have large areas of sunspot
coverage, and have intense X-ray flares and extremely powerful stellar
winds. Stars will remain in the T Tauri stage for about 100 million
years.
Main Sequence Star
The majority of all stars in our galaxy, and even the Universe, are main sequence stars. Our Sun is a main sequence star, and so are our nearest neighbors, Sirius
and Alpha Centauri A. Main sequence stars can vary in size, mass and
brightness, but they’re all doing the same thing: converting hydrogen
into helium in their cores, releasing a tremendous amount of energy.
A
star in the main sequence is in a state of hydrostatic equilibrium.
Gravity is pulling the star inward, and the light pressure from all the
fusion reactions in the star are pushing outward. The inward and outward
forces balance one another out, and the star maintains a spherical
shape. Stars in the main sequence will have a size that depends on their
mass, which defines the amount of gravity pulling them inward.
When a star has consumed its stock of hydrogen in its core, fusion stops and the star no longer generates an outward pressure to counteract the inward pressure pulling it together. A shell of hydrogen around the core ignites continuing the life of the star, but causes it to increase in size dramatically. The aging star has become a red giant star, and can be 100 times larger than it was in its main sequence phase. When this hydrogen fuel is used up, further shells of helium and even heavier elements can be consumed in fusion reactions. The red giant phase of a star’s life will only last a few hundred million years before it runs out of fuel completely and becomes a white dwarf.
White Dwarf Star
When a star has completely run out of hydrogen fuel in its core and it lacks the mass to force higher elements into fusion reaction, it becomes a white dwarf star. The outward light pressure from the fusion reaction stops and the star collapses inward under its own gravity. A white dwarf shines because it was a hot star once, but there’s no fusion reactions happening any more. A white dwarf will just cool down until it because the background temperature of the Universe. This process will take hundreds of billions of years, so no white dwarfs have actually cooled down that far yet.
Red Dwarf Star
Red dwarf stars are the most common kind of stars in the Universe. These are main sequence stars but they have such low mass that they’re much cooler than stars like our Sun. They have another advantage. Red dwarf stars are able to keep the hydrogen fuel mixing into their core, and so they can conserve their fuel for much longer than other stars. Astronomers estimate that some red dwarf stars will burn for up to 10 trillion years. The smallest red dwarfs are 0.075 times the mass of the Sun, and they can have a mass of up to half of the Sun.
Neutron Stars
If a star has between 1.35 and 2.1 times the mass of the Sun, it doesn’t form a white dwarf when it dies. Instead, the star dies in a catastrophic supernova explosion, and the remaining core becomes a neutron star. As its name implies, a neutron star is an exotic type of star that is composed entirely of neutrons. This is because the intense gravity of the neutron star crushes protons and electrons together to form neutrons. If stars are even more massive, they will become black holes instead of neutron stars after the supernova goes off.
Supergiant Stars
The largest stars in the Universe are supergiant stars. These are
monsters with dozens of times the mass of the Sun. Unlike a relatively
stable star like the Sun, supergiants are consuming hydrogen fuel at an
enormous rate and will consume all the fuel in their cores within just a
few million years. Supergiant stars live fast and die young, detonating
as supernovae; completely disintegrating themselves in the process.
We have written many articles about stars on Universe Today. Here’s an article that talks about how massive stars form.Want more information on stars? Here’s Hubblesite’s News Releases about Stars, and more information from NASA’s imagine the Universe.
We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful:
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