Meet a star / Apus

Delta-1 Apodis

Delta-1 Apodis is a red star, among the coolest, in the constellation Apus. 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

760 light years

The light you see from Delta-1 Apodis tonight set off about 760 years ago. Everything we know about it is that much out of date.

Distances this great are hard to measure, and this one could be out by a fifth or more.

How bright

640 Suns

It gives out 640 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 4.68. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 3,500 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-1 ApodisThe 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-1 Apodis
Hipparcos catalogue
HIP 80047
Henry Draper catalogue
HD 145366
Spectral type
M5III

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.