Universe Guide

K Type Stars - Orange Dwarf and Giant Stars

Orange stars are also known as K-Class type stars which are slightly cooler than our own star. Orange dwarf stars are also smaller than our Sun. These orange stars last longer than our Sun. Whilst our star will live for ten billion years of which it is middle-aged, an Orange Star could live for up to 70 billion years.

As orange stars are much cooler than yellow dwarves, any planets that could support life would be located nearer to the star than for larger stars. An Orange star would have a rough temperature of between 3,900 and 5,200. To put that in context, the Suns' surface temperature is about 5,778 K.

Giant Orange Stars

The following two giant stars are known to have planets in orbit round them. Both are the Alpha stars of their respective constellations and both are Zodiac constellations. They double figure times larger than our sun.

An Orange Giant Star example is Hamal which is the brightest star in the constellation of Aries. Hamal has the Bayer reference Alpha Arietis to signify this. The Star is roughly 11 times the size of the Sun.

Another star that is an Orange Giant is Aldebaran which is the brightest star in the constellation of Taurus. Aldebaran is recognised as being brightest by being given the Bayer reference Alpha Tauri. Its estimated at being over 30 times the size of the Sun.


Whilst orange dwarf stars are not as common as Red Dwarf Stars, they are more abundant than Yellow Dwarf Stars. There is a greater range of stars to be searched. Orange Dwarf Stars are less likely to flame their planets being more stable but don't live as long. Any planet orbiting an Orange Dwarf one would have had time to evolve and these are stars of interest for planet finders.

Orange Dwarf Stars are thought of as being the best place to look for alien life. The stars are believed to be stable and therefore life would be able to get a foot hold on the planets. As Orange stars are smaller and colder than yellow stars, the planets would need to be orbiting closer to the star than what a star orbiting a yellow star would need to be.

Stable meaning that the planets would not be flamed by their stars. When it was revealed Proxima Centauri, the nearest star to the Sun had an exoplanet, hope for life turned to disappointment when it was revealed that Proxima flamed it planet therefore cleansing the planet of life.

Ran, (Sadira), a Orange Dwarf Star

A notable orange dwarf is Sadira or Ran as it is officially now known as, in the constellation of Eridanus. At least 2 exoplanets have been detected orbiting round Ran. As they are older and live longer than most other stars such as our own, intelligent alien life forms could have built up a complex civilisation and these are therefore of great interest to those searching for extra-terrestrial life forms. We have not yet received any signals from there yet. Ran is about 10 light years from us, a neighbour.

List of Example Orange Dwarf Stars

Related Pages of Interest :-

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