Meet a star / Piscis Austrinus
Eta Piscis Austrini
Eta Piscis Austrini is a blue-white star, far hotter than the Sun, in the constellation Piscis Austrinus. It is in the long, steady part of its life, making helium from hydrogen in its core, as the Sun is.
How far
820 light years
The light you see from Eta Piscis Austrini tonight set off about 820 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 Everything we know about it is that much out of date.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
370 Suns
It gives out 370 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 5.43. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.
How hot
Hotter than 11,000 K
That is the temperature of its surface, worked out from its colour, so it is a guide and not a measurement. For stars as blue as this one, colour is a poor thermometer: most of their light is ultraviolet, which the eye and this sum do not see, and the true figure can be far higher. 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.
Eta Piscis AustriniThe 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)
- Eta Piscis Austrini
- Hipparcos catalogue
- HIP 108661
- Henry Draper catalogue
- HD 209014
- Spectral type
- B8/B9V
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.