Meet a star / Leo

Chertan

Chertan is a white star, hotter than the Sun, in the constellation Leo. 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

170 light years

The light you see from Chertan tonight set off about 170 years ago. Everything we know about it is that much out of date.

How bright

100 Suns

It gives out 100 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 3.33. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 10,200 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.

ChertanThe Sun

In your sky now

Working it out…

Its names

Its own name
Chertan
By constellation (Bayer)
Theta Leonis
Hipparcos catalogue
HIP 54879
Henry Draper catalogue
HD 97633
Spectral type
A2V

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.