Universe Guide


R71, HD269006, HIP23428

R71 is a blue star that can be located in the constellation of Mensa. R71 is the brightest star in Mensa based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP23428 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD269006.

R71 has alternative name(s), LMC V733.

Location of R71

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 R71, the location is 05h 02m 07.39 and -71d20`13.1 .

Proper Motion of R71

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 0.06 ± 1.24 miliarcseconds/year towards the north and 1.09 ± 1.35 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of R71

R71 has a spectral type of B. This means the star is a blue star. The star has a B-V Colour Index of 0.12 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,178 Kelvin.

R71 Radius has been calculated as being 3.58 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,489,361.81.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.51. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

R71 Apparent and Absolute Magnitudes

R71 has an apparent magnitude of 10.75 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 0.57 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.34. 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 R71

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.92 which gave the calculated distance to R71 as 3545.25 light years away from Earth or 1086.96 parsecs. It would take a spaceship travelling at the speed of light, 3545.25 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 1.31 which put R71 at a distance of 2489.80 light years or 763.36 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. R71 brightness ranges from a magnitude of 10.953 to a magnitude of 10.575 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.

R71 Facts

Alternative Names

Traditional/Proper NameR71
Short NameLMC V733
Hipparcos Library I.D.23428
Henry Draper Designation269006

Visual Facts

Star Type star
Absolute Magnitude0.57 / 1.34
Visual / Apparent Magnitude10.75
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)05h 02m 07.39
Declination (Dec.)-71d20`13.1
Galactic Latitude-34.25 degrees
Galactic Longitude282.82 degrees
1997 Distance from Earth0.92 Parallax (milliarcseconds)
 3545.25 Light Years
 1086.96 Parsecs
2007 Revised Distance from Earth1.31 Parallax (milliarcseconds)
 2489.80 Light Years
 763.36 Parsecs
Proper Motion Dec.0.06 ± 1.24 milliarcseconds/year
Proper Motion RA.1.09 ± 1.35 milliarcseconds/year
B-V Index0.12
Radial Velocity197.00 ± 999.00 km/s
Spectral TypeB
Colour(B) blue

Variable Star Details

Mean Variability Period in Days0.208
Variable Magnitude Range (Brighter - Dimmer)10.575 - 10.953

Estimated Facts

Calculated Effective Temperature8,178 Kelvin

Sources and Links

SIMBAD SourceLink

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