Meet a star / Capricornus

Chi Capricorni

Chi Capricorni is a white star, hotter than the Sun, in the constellation Capricornus. It is in the long, steady part of its life, making helium from hydrogen in its core, as the Sun is.

A drawing in the star's own colour, worked out from its measured colour index. It is not a photograph.

How far

180 light years

The light you see from Chi Capricorni tonight set off about 180 years ago. Everything we know about it is that much out of date.

How bright

20 Suns

It gives out 20 times as much visible light as the Sun. It can just be seen by eye from a really dark place.

Astronomers put its brightness in our sky at magnitude 5.30. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 10,100 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.

Chi CapricorniThe 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)
Chi Capricorni
Hipparcos catalogue
HIP 104365
Henry Draper catalogue
HD 201184
Spectral type
A0V

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.