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Pi5 Orionis, 8 Orionis, HD31237, HIP22797, HR1567

Pi5 Orionis is a blue rotating giant star that can be located in the constellation of Orion. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Pi5 Orionis's Alternative Names

Pi5 Orionis is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR1567. HIP22797 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD31237.

Pi5 Orionis has alternative name(s) :- , pi.05 Ori.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 8 Orionis with it shortened to 8 Ori.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+02 810.

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

Location of Pi5 Orionis

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 Pi5 Orionis, the location is 04h 54m 15.10 and +02° 26` 26.4 .

Proper Motion of Pi5 Orionis

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 0.61 ± 0.19 miliarcseconds/year towards the north and 0.55 ± 0.39 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 24.20000 km/s with an error of about 0.70 km/s .

Pi5 Orionis 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 14898.6200000 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 Pi5 Orionis

Pi5 Orionis has a spectral type of B2III SB. This means the star is a blue giant star. The star is 7751.00000000 Parsecs from the Galactic Centre or terms of Light Years is 25280.9207934400000000s. The star has a B-V Colour Index of -0.17 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 14,786 Kelvin.

Pi5 Orionis Radius has been calculated as being 10.60 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 7,374,443.13.km. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.28 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Pi5 Orionis Apparent and Absolute Magnitudes

Pi5 Orionis has an apparent magnitude of 3.71 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of -4.36 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 Pi5 Orionis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.43 which gave the calculated distance to Pi5 Orionis as 1342.24 light years away from Earth or 411.52 parsecs. It would take a spaceship travelling at the speed of light, 1342.24 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

The star's Galacto-Centric Distance is 7,751.00 Parsecs or 25,280.92 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 Pi5 Orionis

The star is a rotating Rotating ellipsoidal 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. Pi5 Orionis brightness ranges from a magnitude of 3.673 to a magnitude of 3.617 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 3.7 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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Pi5 Orionis Facts

Visual Facts

Alternative NamesHD 31237, HIP 22797, HR 1567, 8 Orionis, 8 Ori, BD+02 810, pi.05 Ori
Star TypeGiant Star
GalaxyMilky Way
Visual / Apparent Magnitude3.71
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)04h 54m 15.10
Declination (Dec.)+02° 26` 26.4
Galactic Latitude-24.56 degrees
Galactic Longitude196.27 degrees
Distance from Earth2.43 Parallax (milliarcseconds)
 1342.24 Light Years
 411.52 Parsecs
Galacto-Centric Distance25,280.92 Light Years / 7,751.00 Parsecs
Proper Motion Dec.0.61 ± 0.19 milliarcseconds/year
Proper Motion RA.0.55 ± 0.39 milliarcseconds/year
B-V Index-0.17
Radial Velocity24.20 ± 0.70 km/s
Iron Abundance-0.28 ± 9.99 Fe/H
Semi-Major Axis8896.00
Stellar Luminosity (Lsun)14,898.62
Spectral TypeB2III SB
Associated / Clustered StarsPi1 Orionis
Pi2 Orionis
Pi4 Orionis
Pi6 Orionis
Colour(B) blue

Variable Star Details

Variable Star ClassRotating
Variable Star TypeRotating ellipsoidal
Mean Variability Period in Days3.701
Variable Magnitude Range (Brighter - Dimmer)3.617 - 3.673

Estimated Facts

Calculated Effective Temperature14,786 Kelvin

Sources and Links

SIMBAD SourceLink

Location of Pi5 Orionis in Orion

Pi5 Orionis (Pi5 Orionis) Location in Orion

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

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