Meet a star / Corona Borealis

Baltesha

Baltesha is a white star, hotter than the Sun, in the constellation Corona Borealis. 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

150 light years

The light you see from Baltesha tonight set off about 150 years ago. Everything we know about it is that much out of date.

How bright

52 Suns

It gives out 52 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 3.81. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 9,900 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.

BalteshaThe Sun

In your sky now

Working it out…

Its names

Its own name
Baltesha
By constellation (Bayer)
Gamma Coronae Borealis
Hipparcos catalogue
HIP 76952
Henry Draper catalogue
HD 140436
Spectral type
A1Vs

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.