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Betelgeuse, Alpha Orionis, 58 Orionis, HD39801, HIP27989, HR2061

Betelgeuse (Alpha Orionis) Location in Orion

Betelgeuse (Alpha Orionis) is a red pulsating supergiant star that can be located in the constellation of Orion. The description is based on the spectral class. Betelgeuse is a main star of the constellation.

Betelgeuse is the 10th brightest star in the night sky and the 2nd brightest star in Orion 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.

Betelgeuse is one of the more famous stars and the eighties film Beetlejuice is a play on the stars name. The film Beetlejuice has nothing to do with space or astronomy, the film is about ghosts hiring another ghost to scare away the human occupants of their building.

Betelgeuse is a likely candidate to go supernova in the astronomical near future. When we talk about near future astronomically, we mean thousands and hundreds of thousands of years, not in the next decade or so..

Betelgeuse is a Cepheid Variable Star which means it grows and shrinks over time. The fact that it grows and shrinks shouldn`t make you underestimate its size, it is truly gigantic. If was in the centre of The Solar System, it would engulf all the rocky planets, Mercury, Venus, Earth and Mars and would extend out past Jupiter but how much further is open to debate.

Betelgeuse's Alternative Names

Alpha Orionis (Alf Ori) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR2061. HIP27989 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD39801.

Betelgeuse has alternative name(s) :- , alf Ori. In Arabic, it is known as Yad al-Jauza'.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 58 Orionis with it shortened to 58 Ori.

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+07 1055.

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

Location of Betelgeuse

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For Betelgeuse, the location is 05h 55m 10.29 and +07° 24` 25.3 .

Radial Velocity and Proper Motion of Betelgeuse

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 11.30 ± 0.58 miliarcseconds/year towards the north and 27.54 ± 0.83 miliarcseconds/year east if we saw them in the horizon.

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 21.91 km/s with an error of about 0.51 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.

Betelgeuse 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 36,554.42 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature, Radius) of Betelgeuse

Betelgeuse has a spectral type of M2Ib. This means the star is a red supergiant star. The star is 7,539.00 Parsecs from the Galactic Centre or terms of Light Years is 24,589.45 s. The star has a B-V Colour Index of 1.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,014 Kelvin.

Betelgeuse has been calculated as 1,180.00 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 821,044,000.00.km. If you need the diameter of the star, you just need to multiple the radius by 2. The star's Iron Abundance is 0.09 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Betelgeuse Apparent and Absolute Magnitudes

Betelgeuse has an apparent magnitude of 0.45 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 -5.14 If you used the 2007 Parallax value, you would get an absolute magnitude of -5.47. 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 Betelgeuse

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.63 which gave the calculated distance to Betelgeuse as 427.47 light years away from Earth or 131.06 parsecs. It would take a spaceship travelling at the speed of light, 427.47 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 6.55 which put Betelgeuse at a distance of 497.96 light years or 152.67 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.

The star's Galacto-Centric Distance is 7,539.00 Parsecs or 24,589.45 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Betelgeuse

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. Betelgeuse brightness ranges from a magnitude of 0.624 to a magnitude of 0.330 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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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Betelgeuse Facts

Visual Facts


Primary / Proper / Traditional NameBetelgeuse
Alternative NamesAlpha Orionis, Alf Ori, Yad al-Jauza', HD 39801, HIP 27989, HR 2061, 58 Orionis, 58 Ori, BD+07 1055, alf Ori
Spectral TypeM2Ib
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
Colour red
GalaxyMilky Way
ConstellationOrion
Absolute Magnitude -5.14 / -5.47
Visual / Apparent Magnitude0.45
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 55m 10.29
Declination (Dec.)+07° 24` 25.3
Galactic Latitude-8.96 degrees
Galactic Longitude199.79 degrees
1997 Distance from Earth7.63 Parallax (milliarcseconds)
 427.47 Light Years
 131.06 Parsecs
2007 Distance from Earth6.55 Parallax (milliarcseconds)
 497.96 Light Years
 152.67 Parsecs
Galacto-Centric Distance24,589.45 Light Years / 7,539.00 Parsecs
Proper Motion Dec.11.30 ± 0.58 milliarcseconds/year
Proper Motion RA.27.54 ± 0.83 milliarcseconds/year
B-V Index1.50
Radial Velocity21.91 ± 0.51 km/s
Iron Abundance0.09 ± 9.99 Fe/H
Eccentricity0.08
Semi-Major Axis8093.00
Stellar Luminosity (Lsun)36,554.42
Brightest in Night Sky10th

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.230
Variable Magnitude Range (Brighter - Dimmer)0.330 - 0.624

Estimated Facts


Radius (x the Sun)1,180.00
Calculated Effective Temperature4,014 Kelvin

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
39801+07 1055.0A0.9000026.0000010.00000M1Red
B14.500001891
C14.200001891
D13.500001877
E11.000001917
P1940

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