Meet a star / Sextans

Delta Sextantis

Delta Sextantis is a blue-white star, far hotter than the Sun, in the constellation Sextans. 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

320 light years

The light you see from Delta Sextantis tonight set off about 320 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 Everything we know about it is that much out of date.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

71 Suns

It gives out 71 times as much visible light as the Sun. It can just be seen by eye from a really dark place.

Astronomers put its brightness in our sky at magnitude 5.19. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 10,800 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.

Delta SextantisThe 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)
Delta Sextantis
Hipparcos catalogue
HIP 51362
Henry Draper catalogue
HD 90882
Spectral type
B9.5V

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.