Meet a star / Boötes

Merga

Merga is a yellow-white star, a little hotter than the Sun, in the constellation Boötes. It is a subgiant: a star just beginning to leave the long, steady part of its life.

A drawing in the star's own colour, worked out from its measured colour index. It is not a photograph.

How far

160 light years

The light you see from Merga tonight set off about 160 years ago. Everything we know about it is that much out of date.

How bright

10 Suns

It gives out 10 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 5.76. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 6,500 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.

MergaThe Sun

In your sky now

Working it out…

Its names

Its own name
Merga
By constellation (Flamsteed)
38 Boötis
Hipparcos catalogue
HIP 72487
Henry Draper catalogue
HD 130945
Spectral type
F7IVw

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.