S Boötis is a

Mira variable Mira variables (named for the prototype star Mira) are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wave ...

in the constellation

Boötes Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...

. It ranges between magnitudes 7.8 and 13.8 over a period of approximately 270 days. It is too faint to be seen with the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

, however when it is near maximum brightness it can be seen with

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

. S Boötis was discovered at Bonn Observatory by Friedrich Wilhelm Argelander in 1860.

References

Boötes Mira variables 126289 M-type giants 070291 Boötis, S Durchmusterung objects Asymptotic-giant-branch stars {{var-star-stub