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Colors of the Big Dipper

The Big Dipper is an asterism, or a collection of stars in the constellation Ursa Major. The Big Dipper is what it's called in America, but in Britain and other places it's known as The Plough. The stars in the Big Dipper are Dubhe, Merak, Megrez, Phecda, Alioth, Mizar, and Alkaid. Dubhe is alpha Ursae Majoris while the others are beta, gamma on down. The Greek alphabets were given in order of the star's brightness at the time with alpha being the brightest. However, Dubhe is no longer the brightest star in the Big Dipper.

The Colors of Stars
- The color of a star usually tells how hot it is. As with metal, the more it passes from red to yellow to blue the hotter it is. An O star is a blue star, and very hot, 25,000 to 40,000 degrees Kelvin. A B star is also blue but cooler, from 11,000 to 25,000 degrees K. The A star is blue to white, and is from 7,500 to 11,000 degrees K. The F star is white, and is from 6,000 to 7,500 degrees K. The G star, like Earth's sun, is white to yellow and is 5,000 to 6,000 degrees K. The K star is orange to red and is 3,500 to 5,000 degrees K. An M star is also red, but 3,000 to 3,500 degrees K.
Dubhe, Merak and Phecda
- Dubhe is either an F7V star or, as some scientists classify it, a K1III star. F would mean the star is yellow white and V would mean that it was still on the main sequence. K means it's orange and the class III means it's a giant. Dubhe is in a multiple-star system that's about 124 light years from earth. Merak is an A1V star about 79 light years from earth, and Phecda is an A0V SB type star. Their classifications mean they are white stars that are still on the main sequence, but Phecda's SB designation means that it's a spectroscopic binary star, which means scientists found out it was a double star through variations in its spectrum.
Megrez, Alioth and Mizar
- Megrez is an A3V variable star. It's a bluish white star whose brightness varies. It's about 81 light years away and has two companions. Alioth is an A0p star and is actually the brightest star in the Big Dipper, even though it is epsilon Ursae Majoris. It's another blue white star about 81 light years from Earth. It's considered a peculiar star because its surface has an unusual chemical signature. Mizar, is an A2V double-star system. Its companion is called Alcor, which is a A5V SB star. American Indians referred to the Mizar and Alcor system as as the horse and rider. The system is about 78 light years from Earth. Both of the stars are white.
Alkaid
- Alkaid is a bluish white star about 101 light years from Earth. Its name means "chief of the daughters of the bier." It's a B3V SB star. Because it's blue white it's extremely bright and hot, from 10,000 to 30,000 K. It's V status tells one that it's still on the main sequence, like Earth's sun and hasn't burned up too much of its hydrogen, like Dubhe, if Dubhe is an orange/red giant.

Astronomy