Universe Guide

HomeFactsConstellationsAuriga

Haldus, Epsilon Aurigae, 7 Aurigae, HD31964, HIP23416

Haldus (Epsilon Aurigae) is a blue to white eclipsing very luminous supergiant star that can be located in the constellation of Auriga. Haldus is the brightest star in Auriga 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.

Epsilon Aurigae is the Bayer Classification for the star. HIP23416 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD31964.

Haldus has alternative name(s), Almaaz, 7 Aurigae, Al Naz , eps Aur.

Location of Haldus

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 Haldus, the location is 05h 01m 58.13 and +43d49`23.9 .

Proper Motion of Haldus

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 -2.66 ± 0.63 miliarcseconds/year towards the north and -0.86 ± 1.29 miliarcseconds/year east if we saw them in the horizon.

Haldus 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 20000.0000000 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 Haldus

Haldus has a spectral type of F0Ia. This means the star is a blue to white supergiant star. The star has a B-V Colour Index of 0.53 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,040 Kelvin.

Haldus Radius has been calculated as being 132.10 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 91,912,031.93.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 138.32. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Haldus Apparent and Absolute Magnitudes

Haldus has an apparent magnitude of 3.03 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 -5.95 If you used the 2007 Parallax value, you would get an absolute magnitude of -6.05. 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 Haldus

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.60 which gave the calculated distance to Haldus as 2038.52 light years away from Earth or 625 parsecs. It would take a spaceship travelling at the speed of light, 2038.52 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 1.53 which put Haldus at a distance of 2131.79 light years or 653.59 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.

Variable Type of Haldus

The star is a eclipsing Beta Persei (Algol)/System with one or both giant or supergiant components 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. Haldus brightness ranges from a magnitude of 3.197 to a magnitude of 3.052 over its variable period. The smaller the magnitude, the brighter the star.

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.

Haldus Facts

Alternative Names

Traditional/Proper NameHaldus
Short Nameeps Aur
Bayer DesignationEpsilon Aurigae
Alternative Name(s)Almaaz, 7 Aurigae, Al Naz
Hipparcos Library I.D.23416
Bonner DurchmusterungBD+43 1166
Henry Draper Designation31964

Visual Facts

Star Typesupergiant star
Absolute Magnitude-5.95 / -6.05
Visual / Apparent Magnitude3.03
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 01m 58.13
Declination (Dec.)+43d49`23.9
Galactic Latitude1.18 degrees
Galactic Longitude162.79 degrees
1997 Distance from Earth1.60 Parallax (milliarcseconds)
 2038.52 Light Years
 625 Parsecs
2007 Revised Distance from Earth1.53 Parallax (milliarcseconds)
 2131.79 Light Years
 653.59 Parsecs
Proper Motion Dec.-2.66 ± 0.63 milliarcseconds/year
Proper Motion RA.-0.86 ± 1.29 milliarcseconds/year
B-V Index0.53
Radial Velocity-10.40 ± 0.40 km/s
Eccentricity0.07
Inclination87.00
Semi-Major Axis22.40
Orbital Period (Days)9887.00
Argument Of Periastron0.00
Spectral TypeF0Ia
Colour(F) blue to white

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeBeta Persei (Algol)/System with one or both giant or supergiant components
Variable Magnitude Range (Brighter - Dimmer)3.052 - 3.197

Estimated Facts

Luminosity (x the Sun)20,000.0000000
Calculated Effective Temperature6,040 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
31964+43 1166.0A1.00000-4.00000F5Yellow/White
B14.000001878
C11.700001878
D12.000001879
+43 1168.0E9.2000010.000002.000001913

Location of Haldus in Auriga


Haldus (Epsilon Aurigae) Location in Auriga

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


Add a Comment


Name:
Email: (Optional)
Comment: