Beta Trianguli Australis

Beta Trianguli Australis is a yellow-white star, a little hotter than the Sun, in the constellation Triangulum Australe. It is a giant: a star that has used up the hydrogen in its core and swollen up.

Fly to it in 3D Find it on the sky map

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

How far

40 light years

The light you see from Beta Trianguli Australis tonight set off about 40 years ago. Everything we know about it is that much out of date.

How bright

9.8 Suns

It gives out 9.8 times as much visible light as the Sun. It is easy to see by eye on a clear night.

Astronomers put its brightness in our sky at magnitude 2.83. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 7,400 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.

Beta Trianguli AustralisThe 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): Beta Trianguli Australis
Hipparcos catalogue: HIP 77952
Henry Draper catalogue: HD 141891
Spectral type: F2III

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.