Meet a star / Sagittarius

Belel

Belel is an orange star, cooler than the Sun, in the constellation Sagittarius. It is a giant: a star that has used up the hydrogen in its core 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

360 light years

The light you see from Belel tonight set off about 360 years ago. Everything we know about it is that much out of date.

At this distance the figure could be out by a tenth or so.

How bright

10 Suns

It gives out 10 times as much visible light as the Sun. It is too faint to see without a telescope.

Astronomers put its brightness in our sky at magnitude 7.55. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 4,700 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.

BelelThe Sun

Its names

Its own name
Belel
Hipparcos catalogue
HIP 95124
Henry Draper catalogue
HD 181342
Spectral type
K0III

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.