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SW Velorum, HD74712, HIP42831

SW Velorum is a blue to white pulsating supergiant star that can be located in the constellation of Vela. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it.

SW Velorum's Alternative Names

HIP42831 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74712.

SW Velorum has alternative name(s) :- , SW Vel.

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

Location of SW Velorum

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 SW Velorum, the location is 08h 43m 38.69 and -47° 24` 11.2 .

Proper Motion of SW Velorum

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 4.07 ± 0.83 miliarcseconds/year towards the north and -6.73 ± 1.00 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 us is 20.80000 km/s with an error of about 0.80 km/s .

SW Velorum 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 313.38 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) of SW Velorum

SW Velorum has a spectral type of F8/G0Ib. This means the star is a blue to white supergiant star. The star is 7,496.00 Parsecs from the Galactic Centre or terms of Light Years is 24,449.20 s. The star has a B-V Colour Index of 0.79 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,444 Kelvin.

SW Velorum Radius has been calculated as being 17.50 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 12,177,622.15.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 37.25. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

SW Velorum Apparent and Absolute Magnitudes

SW Velorum has an apparent magnitude of 8.32 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 -1.11 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.75. 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 SW Velorum

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.30 which gave the calculated distance to SW Velorum as 2508.95 light years away from Earth or 769.23 parsecs. It would take a spaceship travelling at the speed of light, 2508.95 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 0.61 which put SW Velorum at a distance of 5346.94 light years or 1639.34 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 7,496.00 Parsecs or 24,449.20 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 SW Velorum

The star is a pulsating Delta Cepheid 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. SW Velorum brightness ranges from a magnitude of 8.898 to a magnitude of 7.654 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 23.4 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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SW Velorum Facts

Visual Facts


Primary / Proper / Traditional NameSW Velorum
Alternative NamesHD 74712, HIP 42831, SW Vel
Spectral TypeF8/G0Ib
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
Colour blue to white
GalaxyMilky Way
ConstellationVela
Absolute Magnitude-1.11 / -2.75
Visual / Apparent Magnitude8.32
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)08h 43m 38.69
Declination (Dec.)-47° 24` 11.2
Galactic Latitude-3.00 degrees
Galactic Longitude266.19 degrees
1997 Distance from Earth1.30 Parallax (milliarcseconds)
 2508.95 Light Years
 769.23 Parsecs
2007 Distance from Earth0.61 Parallax (milliarcseconds)
 5346.94 Light Years
 1639.34 Parsecs
Galacto-Centric Distance24,449.20 Light Years / 7,496.00 Parsecs
Proper Motion Dec.4.07 ± 0.83 milliarcseconds/year
Proper Motion RA.-6.73 ± 1.00 milliarcseconds/year
B-V Index0.79
Radial Velocity20.80 ± 0.80 km/s
Eccentricity0.08
Semi-Major Axis7236.00
Stellar Luminosity (Lsun)313.38

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days23.435
Variable Magnitude Range (Brighter - Dimmer)7.654 - 8.898

Estimated Facts


Calculated Effective Temperature5,444 Kelvin

Sources and Links


SIMBAD SourceLink

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