Universe Guide


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

Betelgeuse (Alpha Orionis) is a red pulsating very luminous supergiant star that can be located in the constellation of Orion. Betelgeuse is the 11th 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.

Alpha Orionis 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'.

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.

Location of Betelgeuse

The location of the star in the galaxy 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 +07d24`25.3 .

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.

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 53000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

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 7539.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24589.4545041600000000s. 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. 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.

Betelgeuse Facts

Alternative Names

Traditional/Proper NameBetelgeuse
Flamsteed Name58 Orionis
Flamsteed Short Name58 Ori
Short Namealf Ori
Arabic NameYad al-Jauza'
English MeaningHand of Orion
Bayer DesignationAlpha Orionis
Hipparcos Library I.D.27989
Yale Bright Star Catalogue (HR) Id2061
Bonner DurchmusterungBD+07 1055
Henry Draper Designation39801

Visual Facts

Star Typesupergiant star
Absolute Magnitude-5.14 / -5.47
Visual / Apparent Magnitude0.45
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 55m 10.29
Declination (Dec.)+07d24`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 Revised 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
Spectral TypeM2Ib
Brightest in Night Sky11th
Colour(M) Red

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
Luminosity (x the Sun)53,000.0000000
Calculated Effective Temperature4,014 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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

Location of Betelgeuse in Orion

Betelgeuse (Alpha Orionis) Location in Orion

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

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