9 Geminorum is a blue pulsating supergiant star that can be located in the constellation of Gemini. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
The Id of the star in the Yale Bright Star Catalogue is HR2240. HIP29840 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD43384.
9 Geminorum has alternative name(s) :- , PX Gem.
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 9 Geminorum with it shortened to 9 Gem.>
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+23 1275.
More details on star alternative names can be found at Star Names.
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 9 Geminorum, the location is 06h 16m 58.71 and +23° 44` 27.3 .
9 Geminorum has a spectral type of B3Ia. This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.44 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,276 Kelvin.
9 Geminorum Radius has been calculated as being 28.55 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 19,863,206.21.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 -0.14 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.
9 Geminorum has an apparent magnitude of 6.24 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 -2.79 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.56 which gave the calculated distance to 9 Geminorum as 2090.79 light years away from Earth or 641.03 parsecs. It would take a spaceship travelling at the speed of light, 2090.79 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a pulsating Alpha Cygnus 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. 9 Geminorum brightness ranges from a magnitude of 6.388 to a magnitude of 6.333 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 13.7 days (variability).
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.
|Alternative Names||HD 43384, HIP 29840, HR 2240, 9 Gem, BD+23 1275, PX Gem|
|Star Type||very luminous Supergiant Star|
|Visual / Apparent Magnitude||6.24|
|Naked Eye Visible||Yes - Magnitudes|
|Right Ascension (R.A.)||06h 16m 58.71|
|Declination (Dec.)||+23° 44` 27.3|
|Galactic Latitude||3.53 degrees|
|Galactic Longitude||187.99 degrees|
|Distance from Earth||1.56 Parallax (milliarcseconds)|
|2090.79 Light Years|
|Radial Velocity||13.20 ± 2.90 km/s|
|Iron Abundance||-0.14 ± 9.99 Fe/H|
|Variable Star Class||Pulsating|
|Variable Star Type||Alpha Cygnus|
|Mean Variability Period in Days||13.700|
|Variable Magnitude Range (Brighter - Dimmer)||6.333 - 6.388|
|Calculated Effective Temperature||6,276 Kelvin|