Meet a star / Andromeda

Shimu

Shimu is an orange star, cooler than the Sun, in the constellation Andromeda. It is a bright giant: a star that has left the steady part of its life and swollen up.

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

How far

190 light years

The light you see from Shimu tonight set off about 190 years ago. Everything we know about it is that much out of date.

How bright

68 Suns

It gives out 68 times as much visible light as the Sun. It can be seen by eye away from bright lights.

Astronomers put its brightness in our sky at magnitude 4.08. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 4,500 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.

ShimuThe Sun

In your sky now

Working it out…

Its names

Its own name
Shimu
By constellation (Bayer)
Zeta Andromedae
Hipparcos catalogue
HIP 3693
Henry Draper catalogue
HD 4502
Spectral type
K1II

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.