Epsilon Pegasi (Bayer designation ε Pegasi), commonly known by its traditional name Enif, is a bright, orange K‑type supergiant star that marks the nose of the winged horse in the constellation Pegasus. Easily visible to the naked eye, Enif is notable for its cool surface temperature and large radius, which give it an orange hue and a high intrinsic luminosity.
Physical characteristics
- Spectral type: commonly classified as a K‑type supergiant (often quoted around K2 Ib).
- Apparent brightness: around magnitude 2.4, making it one of the brighter stars in Pegasus.
- Distance: typically estimated at several hundred light‑years away (values commonly cited in the range of a few hundred to about seven hundred light‑years depending on measurement).
- Size and luminosity: Enif’s radius is many tens to a few hundred times that of the Sun and its luminosity is thousands of times solar; such estimates vary with models and parallax input.
- Temperature and color: its effective temperature is cool for a luminous star (a few thousand kelvins), producing an orange to reddish appearance.
Because it is an evolved, massive object, physical quantities for Enif often come with substantial uncertainties. Mass estimates place it among the intermediate to high‑mass stars that have exhausted core hydrogen and expanded into a supergiant phase.
Name and cultural history
The name "Enif" derives from Arabic, meaning "nose," referring to the star’s position at the horse’s muzzle in classical celestial imagery. As a conspicuous star in a well-known constellation, Enif has been cataloged and referenced by observers from antiquity through modern astronomy and appears in many star atlases and navigation charts.
Enif has also drawn attention in spectral and evolutionary studies because K‑type supergiants occupy an important stage in the lifecycle of moderately massive stars. They are used as benchmarks for studying stellar structure, mass loss, and late‑stage evolution before more dramatic end states.
Observation and significance
Observers can find Enif as a bright, orange point at the southeastern corner of the Great Square of Pegasus. It is an attractive target for amateur telescopes because of its color and relative isolation from nearby bright stars. Professional interest centers on its role as a laboratory for stellar atmosphere physics and for calibrating distance and luminosity scales for evolved stars.
Notable facts: Enif’s color and size make it a clear example of a cool supergiant, its traditional name reflects long‑standing human associations with the Pegasus figure, and ongoing measurements continue to refine its distance and intrinsic properties.