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WR 40, HD96548, HIP54283

WR 40 is a eruptive Wolf-Rayet star that can be located in the constellation of Carina. The star can not be seen by the naked eye, you need a telescope to see it.

HIP54283 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD96548.

WR 40 has alternative name(s), V385 Car.

Location of WR 40

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 40, the location is 11h 06m 17.21 and -65d 30` 35.2 .

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 40

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 -2.80 ± 0.46 miliarcseconds/year towards the north and -2.39 ± 0.59 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Temperature, Radius) of WR 40

WR 40 has a spectral type of WN8 (SB1). This means the star is a Wolf-Rayet star. The star has a B-V Colour Index of 0.1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,434 Kelvin.

WR 40 Radius has been calculated as being 62.94 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 43,790,255.62.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 22.95. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

WR 40 Apparent and Absolute Magnitudes

WR 40 has an apparent magnitude of 7.70 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 -5.79 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.60. 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 40

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.20 which gave the calculated distance to WR 40 as 16308.17 light years away from Earth or 5000 parsecs. It would take a spaceship travelling at the speed of light, 16308.17 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 0.55 which put WR 40 at a distance of 5930.24 light years or 1818.18 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 40

The star is a eruptive 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. WR 40 brightness ranges from a magnitude of 7.721 to a magnitude of 7.601 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 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 40 Facts

Alternative Names

Traditional/Proper NameWR 40
Short NameV385 Car
Hipparcos Library I.D.54283
Henry Draper Designation96548
Wolf-Rayet Id40

Visual Facts

Star Type Wolf-Rayet star
Absolute Magnitude-5.79 / -3.60
Visual / Apparent Magnitude7.70
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)11h 06m 17.21
Declination (Dec.)-65d 30` 35.2
Galactic Latitude-4.83 degrees
Galactic Longitude292.31 degrees
1997 Distance from Earth0.20 Parallax (milliarcseconds)
 16308.17 Light Years
 5000 Parsecs
2007 Revised Distance from Earth0.55 Parallax (milliarcseconds)
 5930.24 Light Years
 1818.18 Parsecs
Proper Motion Dec.-2.80 ± 0.46 milliarcseconds/year
Proper Motion RA.-2.39 ± 0.59 milliarcseconds/year
B-V Index0.10
Spectral TypeWN8 (SB1)

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeIrregular
Mean Variability Period in Days0.099
Variable Magnitude Range (Brighter - Dimmer)7.601 - 7.721

Estimated Facts

Calculated Effective Temperature8,434 Kelvin

Sources and Links

SIMBAD SourceLink

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