Universe Guide


WR 22, HD92740, HIP52308

WR 22 is a eclipsing binary system Wolf-Rayet star that can be located in the constellation of Carina. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP52308 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD92740.

WR 22 has alternative name(s), V429 Car.

Location of WR 22

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 WR 22, the location is 10h 41m 17.52 and -59d40`36.9 .

Wolf-Rayet Star

The star is a Wolf-Rayet, a rare type of star of which not many are known. These stars are extremely luminous and large compared to our Sun. They live fast and die hard in a matter of millions not billions of years like our Sun. They exhaust their hydrogen supplies, turning to other gasses and expand outwards with massive solar winds, moving a step closer in the stellar evolution towards their death in a super or hypernova explosion.

Proper Motion of WR 22

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 2.86 ± 0.28 miliarcseconds/year towards the north and -7.71 ± 0.34 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Temperature, Radius) of WR 22

WR 22 has a spectral type of WN7 + A(SB1). This means the star is a Wolf-Rayet star. The star has a B-V Colour Index of 0.08 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,721 Kelvin.

WR 22 Radius has been calculated as being 35.96 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 25,020,823.31.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 274.07. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

WR 22 Apparent and Absolute Magnitudes

WR 22 has an apparent magnitude of 6.35 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 -4.72 If you used the 2007 Parallax value, you would get an absolute magnitude of -9.13. 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 WR 22

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.61 which gave the calculated distance to WR 22 as 5346.94 light years away from Earth or 1639.34 parsecs. It would take a spaceship travelling at the speed of light, 5346.94 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 0.08 which put WR 22 at a distance of 40770.42 light years or 12500 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 WR 22

The star is a eclipsing binary system Beta Persei (Algol) 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. WR 22 brightness ranges from a magnitude of 6.407 to a magnitude of 6.364 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.

WR 22 Facts

Alternative Names

Traditional/Proper NameWR 22
Short NameV429 Car
Hipparcos Library I.D.52308
Henry Draper Designation92740
Wolf-Rayet Id22

Visual Facts

Star Type Wolf-Rayet star
Absolute Magnitude-4.72 / -9.13
Visual / Apparent Magnitude6.35
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 41m 17.52
Declination (Dec.)-59d40`36.9
Galactic Latitude-0.85 degrees
Galactic Longitude287.17 degrees
1997 Distance from Earth0.61 Parallax (milliarcseconds)
 5346.94 Light Years
 1639.34 Parsecs
2007 Revised Distance from Earth0.08 Parallax (milliarcseconds)
 40770.42 Light Years
 12500 Parsecs
Proper Motion Dec.2.86 ± 0.28 milliarcseconds/year
Proper Motion RA.-7.71 ± 0.34 milliarcseconds/year
B-V Index0.08
Radial Velocity-28.00 ± 7.40 km/s
Spectral TypeWN7 + A(SB1)

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Persei (Algol)
Mean Variability Period in Days0.031
Variable Magnitude Range (Brighter - Dimmer)6.364 - 6.407

Estimated Facts

Calculated Effective Temperature8,721 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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