Meet a star / Perseus

Sarvvis

Sarvvis is a blue-white star, far hotter than the Sun, in the constellation Perseus. 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

520 light years

The light you see from Sarvvis tonight set off about 520 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 Everything we know about it is that much out of date.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

1,400 Suns

It gives out 1,400 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 3.01. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 16,000 K

That is the temperature of its surface, worked out from its spectral type, B5III SB, with a standard table of how hot stars of each type are. It is a guide and not a measurement, and could be out by a tenth or so. For stars as hot as this, colour is a poor thermometer, because most of their light is ultraviolet, so the type is the better guide. 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.

SarvvisThe Sun

In your sky now

Working it out…

Its names

Its own name
Sarvvis
By constellation (Bayer)
Delta Persei
Hipparcos catalogue
HIP 17358
Henry Draper catalogue
HD 22928
Spectral type
B5III SB

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 read from the spectral type with the table of Pecaut and Mamajek (2013), and the words are written for this site.

To read more: Colour and brightness, How stars live and die, Measuring distance.