Why are blue stars hot and red stars cool?

Answer 1

The short answer is "hot", but it's all relative.

The surface temperature of stars varies from around 2,500 degrees C, to about 40,000. The sun (a star which appears special to us simply because we happen to be in orbit around it) has a surface temperature is around 6,000 degrees.

All stars in the Universe are relatively hot compared to what we experience on Earth. Most stars are at least a few thousand degrees hot (in Fahrenheit). (Kelvin)

Though, there is a theoretical star called a 'black dwarf'. This theoretical star is said to be negative hundreds of degrees, since it is thought to be a star that burned all possible fuel, and no longer emits heat or light. It is theoretical because the time thought to create this hypothetical star is about the age of the universe now, so it isn't surprising that one hasn't shown up in the records yet.

Theoretically, no, not all stars are hot. Currently, yes, most stars are relatively hot to what we experience on Earth.

There might be a black dwarf in view right now, but since it doesn't emit heat or light, we may never know if one exists or find one at all.

Answer 2

Stars that appear "red" are usually larger and coolerthan yellow or blue ones. The color of a star is fairly representative of the temperature of an equivalent "black-body" radiation source, with blue being the hottest (O class) and red the coolest (M class stars).

Red dwarfs, because of the way they fuse hydrogen, are also red, but much smaller than any of the main sequence stars. The Sun will likely swell into a red giant, with a diameter up to 300 million kilometers, then lose mass and shrink to a white dwarf star.

Answer 3

On a Hertzsprung-Russell diagram, blue stars are considered to be the hottest, reaching temperatures of over 25,000 degrees Kelvin. After blue follows white, then yellow, orange, and red (the coolest of stars).

Answer 4

-- The peak wavelength of a star's radiation is proportional to its surface temperature.

(Actually to T4, but the concept is sound.)

-- So a star with a relatively cooler surface radiates a spectrum that peaks at a

lower wavelength than that of a relatively hotter star does.

-- A relatively cooler star might peak in the red, or even in the infrared. And

a relatively hotter star might peak in the blue, or even in the UV.

-- So it's not that blue stars are hot. It's that hot stars are blue.

Answer 5

Blue stars are hot because they have higher surface temperatures, around 10,000-40,000 Kelvin, causing them to emit more blue light. Red stars are cooler than blue stars, with temperatures ranging from 2,500-5,000 Kelvin, which results in them emitting more red light. The color of a star is determined by its surface temperature, with hotter stars appearing blue and cooler stars appearing red.

Answer 6

Red stars are hot.The blue star is the hottest of all stars.

Answer 7

cool stars appear to be red because the temperature is low beteen 1900 digees to 3950 digrees faninhite

Answer 8

Immensely hot, our sun is a star.