Stars are wondrous and amazing things just like moon, asteroids, and other planetary objects. They differ in shapes, sizes and colors.
For centuries, astronomers have discovered different stars that have unique properties and colors. Their color may range from bluish to white or yellow to red.
The stars different colors are basically the difference in their temperature and composition. The light that each star will emit is the result of their combination of their wavelengths.
Reasons on the Stars Different Colors
Men have always gazed through the stars in wonder and owe. 200 years ago, most people think that all stars are white since the lights they produce will have to pass through the earth’s atmosphere.
They will also appear like they are twinkling. Nowadays, we are now aware that the colors of the stars are as many as the colors of the rainbow. Here are some reasons behind the change in colors.
Composition Can Dictate the Color of the Star
Stars are composed of different elements. Each element will emit varying wavelengths of radiation once they are heated. The primary composition of most stars are helium and hydrogen.
However, it is also composed of different elements. The colors of the stars are basically the combination of these electromagnetic wavelengths. This is also known as Planck’s Curve.
The wavelength where the stars will release the light is known as the peak wavelength that is also referred to as Wien’s Law.
Nonetheless, how our eyes will perceive the star color can also be affected by host of factors related with the Planck’s Curve. Once all these factors have been mixed, the stars will appear white on our naked eye. The real color of the star will appear lighter.
Let us consider the closest star to our planet which is the sun. While the peak emission of the sun is green it still looks a pale shade of yellow.
The composition of the star is developed through its long years of formation. The stars are born from a nebula that is composed of millions of dusts and gasses. Each of them will be different from the other.
While nebulas are primarily composed of hydrogen, they can also carry a range of other elements. This contributes to the changes in the colors of the stars.
Distance and Temperature May Also Affect the Star’s Color
Another factor that affects the colors of the star would be its temperature. As the heat of the star builds up, the energy that is being radiated by the star will also increase.
The peak wavelength will also become shorter. Therefore, as the star becomes hot, the light that is being emitted by the star will move closer to the blue spectrum.
As we all know, blue is considered as the hottest star. This may be quite interesting to some since blue originally belongs to the cooler spectrum.
Another factor that might influence the color of the stars would be the distance. The impact of distance towards the color is known as Doppler Effect. The frequency of the light can decrease or increase depending on the distance between the observer and the source of the light.
Stars are Unique
When you look up at the sky at night, more than 4,000 eyes will be visible to your naked eye. They may all look white but, they have different colors.
By studying the plethora of stars in the universe you will be able to uncover the complex truth about each star and how peculiar they are from each other. They may differ on their mass, luminosity, age, distance, and temperature.
The Star’s Behavior is Similar to an Iron Rod
The behavior of the stars is based on the physic’s concept of blackbody radiation. You may look at an iron rod to have a better understanding about it.
Once this has been heated, the color of the iron rod will change from red and will eventually turn into orange. Continuous exposure to the heat will prompt the light to change to yellow and will progress to a light color.
As the temperature increase, this will then transform into a blue color. Perhaps the perfect example of the blue star would be the Rigel found in the constellation of Orion. It has luminosity that is 40,000 times brighter than our sun.
Star Classification According to their Color
As defined by the Wien’s Law, the star can be classified according to the temperature of their surface. However, this type of classification, has posed a serious challenged on the stars that are considerably further from us. Here are the standard classes of the stars.
O Stars
The O type of stars include most of the blue stars that have surface temperature of 20,000-35,000K. They emit a considerable amount of thermal energy that the hydrogen composition of the stars on the surface has been completely ionized that makes the lines weak. The electromagnetic wavelength of the O-stars is moving towards the blue end.
B Stars
These are blue-white stars that have surface temperature of about 15,000K. Some of the stars that belong in this category are exhibiting powerful lines of helium that are non-ionized. They have an incredibly solid magnetic field particularly on their photosphere.
A Stars
These are white stars with small hint of blue that are the most common stars that can be visible to us. They are also known for their powerful hydrogen lines and different metals that have been ionized.
About 0.625% of the stars are considered A-type. Some of the renowned stars that fall in this category are Deneb, Sirius A, Eta Leonis, and Vega.
F Stars
These stars have strengthening lines of Calcium, Potassium, and Hydrogen. They have a weaker line of hydrogen and other ionized metals compared to the star spectrum mentioned above. They are white stars that make up 3.03% of the stars in the main sequence.
G Stars
The G-type of stars is where our sun is categorized. Their hydrogen line is even weaker than the stars in the F category.
However, apart from the ionized metals, neutral metals are also found in their composition. This makes up at least 7.5% of stars in the main composition.
K Stars
These have an orangish shade that are cooler compared to our sun. Their hydrogen line is known to be extremely weak.
M Stars
These are the most common type of stars. At least 76% of the stars belong in this category. Most of the stars in this spectrum are red dwarfs. Nonetheless, super giants that are found in the Milky Way that belongs here.
Different Type of Stars
Blue Stars
These are hot stars that are found in the spiral galaxies. Their light can illuminate the surrounding gas clouds and dust. This will make the entire area appear blue. Their spectral type is usually B and O.
Yellow Dwarfs
Alpha Centauri A is considered as yellow dwarf. G-type of stars are commonly called yellow dwarfs. The solar mass of yellow dwarf is about 0.84-1.15.
Orange Dwarf
These are type of stars that have spike an interest towards searching for extraterrestrial life. The UV radiation that they release is significantly lesser compared to the G-type of stars. Their capacity to remain stable for about 30 billion years is also surprising.
Red Dwarf
The red dwarf makes up most of the stars found in the Milky Way. However, since their color is very faint, it is quite impossible to see them if you don’t use any visual aid.
The process of hydrogen conversion occurs not only in the core. Therefore, the process of nuclear fusion has considerably slowed down.
Blue Giant
The term used to describe these types of stars applies to various stars that managed to evolve off their main sequence. Nonetheless, those stars with II and III luminosity are still considered as blue giant simply because of convenience.
Blue Supergiants
Scientifically, these are referred to as OB supergiants. They are larger compared to our sun. They are also smaller than the red supergiant.
Red Giants
These are smaller stars and not as massive as the supergiants. They have an average weight of 0.3-8 solar mass. The stars that belong in the spectrum of RBG are commonly red giants.
Red Supergiants
They are the stars that has depleted their hydrogen resource found in their core. Therefore, there is a considerable expansion on the outer layer of their main sequence. With regards to the bulk, they are known as the biggest star despite of not being the most massive and luminous.
Brown Dwarfs
These are the failed stars. They are not big enough to sustain he process of converting hydrogen to helium.
Conclusion
To sum it all up, the stars different colors depends on their composition, temperature, size, and the distance from the observer. As time passes by, these characteristics may change.
Some stars will appear darker and others will look more bluish. As you observe and learn more about these stars, you will be able to understand the long and profound history of our universe.
Many thanks for taking the time to read this article !