Universe Guide

Enif (Epsilon Pegasi, 8 Pegasi) Star Facts

Enif Facts

  • Enif is a pulsating supergiant star that can be located in the constellation of Pegasus. The description is based on the spectral class.
  • Enif is a main star of the constellation outline.
  • Based on the spectral type (K2Ibvar) of the star, the star's colour is orange to red .
  • Enif is the 83rd brightest star in the night sky and is the brightest star in Pegasus based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Enif has a radius that is 185.00 times bigger than the Suns. Radius
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 689.56 light years away from us. Distance

Enif's Alternative Names

Epsilon Pegasi (Eps Peg) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR8308. HIP107315 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD206778.

Enif has alternative name(s) :- , eps Peg. In Arabic, it is known as Al-Anf.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 8 Pegasi. The Flamsteed name can be shortened to 8 Peg.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 11 G. Pegasi. There are no stars with a Gould designation in Ursa Major for example.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+09 4891.

More details on objects' alternative names can be found at Star Names .

Location of Enif

The location of the supergiant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For Enif, the location is 21h 44m 11.14 and +09° 52` 30.0 .

Radial Velocity and Proper Motion of Enif

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 0.44 ± 0.11 milliarcseconds/year towards the north and 26.92 ± 0.17 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 3.39000 km/s with an error of about 0.06 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Enif

Enif Colour and Temperature

Based on the star's spectral type of K2Ibvar , Enif's colour and type is orange to red supergiant star. The star's effective temperature is 4,379 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

Enif Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 12,957.83 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Enif Radius

Enif Radius has been calculated as being 185.00 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 128,723,000.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.

Enif Mass

The Enif's solar mass is 11.70 times that of our star, the Sun. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

Enif Iron Abundance

Enif Iron Abundance is -0.06 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

Enif Apparent and Absolute Magnitudes

Enif has an apparent magnitude of 2.38 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of -4.19 If you used the 2007 Parallax value, you would get an absolute magnitude of -4.25. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Enif

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.85000 which gave the calculated distance to Enif as 672.50 light years away from Earth or 206.19 parsecs. If you want that in miles, it is about 3,953,375,563,465,977.73, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 4.73000 which put Enif at a distance of 689.56 light years or 211.42 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 43,608,201.47 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,328.00 Parsecs or 23,901.25 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Enif

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736628,302,177.57
Speed of Sound (Mach 1)767.269602,696,580.59
Concorde (Mach 2)1,534.54301,347,897.54
New Horizons Probe33,00014,013,042.51
Speed of Light670,616,629.00689.56

Variable Type of Enif

The star is a pulsating Slow Irregular variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Enif brightness ranges from a magnitude of 2.566 to a magnitude of 2.528 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 days (variability).

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional Enif Facts and Figures

Visual Facts

Primary / Proper / Traditional NameEnif
Alternative NamesEpsilon Pegasi, Eps Peg, Al-Anf, HD 206778, HIP 107315, HR 8308, 11 G. Pegasi, 8 Pegasi, 8 Peg, BD+09 4891, eps Peg
Spectral TypeK2Ibvar
Constellation's Main StarYes
Multiple Star SystemYes
Star Type very luminous Supergiant Star less luminour Supergiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude -4.19 / -4.25
Visual / Apparent Magnitude2.38
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 44m 11.14
Declination (Dec.)+09° 52` 30.0
Galactic Latitude-31.45748629 degrees
Galactic Longitude65.57092524 degrees
1997 Distance from Earth4.85000 Parallax (milliarcseconds)
 672.50 Light Years
 206.19 Parsecs
2007 Distance from Earth4.73000 Parallax (milliarcseconds)
 689.56 Light Years
 211.42 Parsecs
 43,608,201.47 Astronomical Units
Galacto-Centric Distance23,901.25 Light Years / 7,328.00 Parsecs
Proper Motion Dec.0.44000 ± 0.11000 milliarcseconds/year
Proper Motion RA.26.92000 ± 0.17000 milliarcseconds/year
B-V Index1.52
Radial Velocity3.39000 ± 0.06 km/s
Iron Abundance-0.0600 ± 9.99 Fe/H
Semi-Major Axis8432.0000000
Stellar Luminosity (Lsun)12957.8300000
Brightest in Night Sky83rd

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.020
Variable Magnitude Range (Brighter - Dimmer)2.528 - 2.566

Estimated Calculated Facts

Radius (x the Sun)185.00
Effective Temperature3,971 Kelvin
Mass Compared to the Sun11.70

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
206778+09 4891.0A2.5000029.000005.00000K0Orange
+09 4890.0C8.50000-45.00000-16.000001913

Location of Enif in Pegasus

Enif Location in Pegasus

The map was generated using Night Vision, an awesome free application by Brian Simpson.

Pegasus Main Stars

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