Epsilon Indi
Epsilon Indi is an orange star, cooler than the Sun, in the constellation Indus. It is in the long, steady part of its life, making helium from hydrogen in its core, as the Sun is.
How far
12 light years
The light you see from Epsilon Indi tonight set off about 12 years ago. Everything we know about it is that much out of date.
How bright
0.15 of a Sun
It gives out 15 per cent of the Sun's visible light. It can be seen by eye away from bright lights.
Astronomers put its brightness in our sky at magnitude 4.69. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.
How hot
About 4,600 K
That is the temperature of its surface, worked out from its colour, so it is a guide and not a measurement. It could be out by a few hundred degrees. The Sun's is 5,772 K. Hotter stars are bluer and cooler stars are redder, the same way a poker in a fire goes from red to white.
Epsilon IndiThe Sun
In your sky now
Working it out…
Its names
It has no name of its own. Its name by constellation is a Greek letter and the constellation it is in, a way of naming begun by Johann Bayer in 1603.
- By constellation (Bayer)
- Epsilon Indi
- Hipparcos catalogue
- HIP 108870
- Henry Draper catalogue
- HD 209100
- Spectral type
- K5V
Where this comes from
Distance, brightness, colour and spectral type are from the HYG star database, version 4.4, by David Nash, shared under a Creative Commons Attribution-ShareAlike 4.0 licence. Its distances are those measured by the Hipparcos satellite. The temperature is worked out here from the colour with the formula of Ballesteros (2012), and the words are written for this site.
To read more: Colour and brightness, How stars live and die, Measuring distance.