What color are the stars

star colors

In the universe there are billions of stars that are located and distributed throughout space. Each of them has unique characteristics and among those characteristics we have the color. Throughout human history, questions have been asked What color are the stars.

For this reason, in this article we are going to tell you what color the stars are, how you can tell and how it affects whether they have one color or another.

What color are the stars

what color are the stars in the universe

In the sky we can find thousands of stars shining, although each star has a different brightness, depending on its size, "age" or distance from us. But if we look at them closely or look at them through a telescope, we see that, in addition, the stars can have different colors or shades, from red to blue. So we find bluer stars or redder stars. Such is the case with the brilliant Antares, whose name aptly means "Rival of Mars" as it competes with the intense colors of the red planet.

The color of the stars basically depends on the temperature of their surfaces. Thus, although it seems contradictory, blue stars are the hottest and red stars are the coldest (or rather, the least hot). We can easily understand this apparent contradiction if we remember the spectrum that almost all of us were taught in school as children. According to the electromagnetic spectrum, ultraviolet light is much stronger than infrared light. Therefore, blue implies more intense and energetic radiation and therefore corresponds to higher temperatures.

So, in astronomy, stars change color depending on their temperature and age. In the sky we find blue and white stars or orange or red stars. For example, the Blue Star Bellatrix has a temperature of more than 25.000 Kelvin. Reddish stars like Betelgeuse reach temperatures of only 2000 K.

Classification of stars by color

What color are the stars

In astronomy, stars are divided into 7 different classes based on their color and size. These categories are represented by letters and are subdivided into numbers. For example, the youngest (smallest, hottest) stars are blue and are classified as O-type stars. On the other hand, the oldest (largest, coolest) stars are classified as M-type stars. Our Sun it is about the size of an intermediate-mass star and has a yellowish tinge. It has a surface temperature of around 5000-6000 Kelvin and is considered a G2 star. As it ages, the sun gets bigger and colder, while it gets redder. But that's still billions of years away

The color of the stars indicates their age

Also, the color of the stars gives us an idea of ​​their age. As a result, the youngest stars have a bluer hue, while the older stars have a reddish hue. This is because the younger the star, the more energy it produces and the higher the temperature it reaches. Conversely, as stars age, they produce less energy and cool, turning redder. However, this relationship between its age and temperature is not universal because it depends on the size of the star. If a star is very massive, it will burn up fuel faster and turn reddish in less time. On the contrary, less massive stars "live" longer and take longer to turn blue.

In some cases, we see stars that are very close to each other and have very contrasting colors. This is the case of the albino star in Cygnus. Naked eye, Albireo looks like an ordinary star. But with a telescope or binoculars we will see it as a single star of a very different color. The brightest star is yellow (Albireo A) and its companion is blue (Albireo B). It is undoubtedly one of the most beautiful and easy to see doubles.

blink or wink

star size

Sirius is one of the brightest in the northern hemisphere and is easily visible in winter. When Sirius is very close to the horizon, it seems to glow in all colors like party lights. This phenomenon is by no means produced by a star, but by something much closer: our atmosphere. The different layers of air at different temperatures in our atmosphere mean that light from the star does not follow a straight path, but is refracted over and over again as it travels through our atmosphere. This is known to amateur astronomers as atmospheric turbulence, which causes stars to "blink."

Clearly you will have noticed the wild wobble of the stars, that constant "blink" or "wink". Also, you will notice that this flickering becomes more intense as we get closer to the horizon. This is because the closer a star is to the horizon, the more of the atmosphere its light has to pass through to reach us, and therefore the more it is affected by atmospheric turbulence. Well, in the case of Sirius, which is very bright, the effect is even more pronounced. Thus, on erratic nights and near the horizon, this turbulence makes the star appear not to be stationary, and we see it as casting different shadows. A natural and everyday effect alien to the stars, which also affects the quality of observations and astrophotographs.

How long do the stars shine?

Stars can shine for billions of years. But nothing lasts forever. The fuel they have for nuclear reactions is limited and is running out. When there is no hydrogen to burn, helium fusion takes over, but unlike the previous one, it is much more energetic. This causes the star to expand thousands of times its original size at the end of its life, becoming a giant. The expansion also causes them to lose heat at the surface and have to distribute more energy over a larger area, which is why they turn red. The exception are these red giant stars, known as the belt of giant stars.

Red giants don't last very long and quickly consume what little fuel they have left. When this happens, the nuclear reactions inside the star run out to sustain the star: gravity pulls on its entire surface and shrinks the star until it becomes a dwarf. Due to this brutal compression, the energy is concentrated and its surface temperature rises, essentially changing its glow to white. The corpse of a star is a white dwarf. These stellar corpses are another exception to main sequence stars.

I hope that with this information you can learn more about what color the stars are and what it influences.

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