Universe Guide

Phi Geminorum (83 Geminorum) Star Facts

Phi Geminorum Facts

  • Phi Geminorum is a main sequence star that can be located in the constellation of Gemini. The description is based on the spectral class.
  • Phi Geminorum is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (A3V) of the star, the star's colour is blue - white .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 222.49 light years away from us. Distance

Phi Geminorum's Alternative Names

Phi Geminorum (Phi Gem) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR3067. HIP38538 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD64145.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 83 Geminorum. The Flamsteed name can be shortened to 83 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+27 1499.

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

Location of Phi Geminorum

The location of the main sequence star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For Phi Geminorum, the location is 07h 53m 29.84 and +26° 45` 57.1 .

Radial Velocity and Proper Motion of Phi Geminorum

Proper Motion

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 -30.10 ± 0.42 milliarcseconds/year towards the north and -34.69 ± 0.73 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 8.00000 km/s with an error of about 2.80 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Phi Geminorum

Phi Geminorum Colour and Temperature

Based on the star's spectral type of A3V , Phi Geminorum's colour and type is blue - white main sequence star. The star has a B-V Colour Index of 0.09 which means the star's temperature is about 8,538 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Phi Geminorum 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 40.81 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Phi Geminorum Radius

Phi Geminorum estimated radius has been calculated as being 3.37 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,347,850.95.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.9524547541251233937465892271. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Phi Geminorum Apparent and Absolute Magnitudes

Phi Geminorum has an apparent magnitude of 4.97 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 0.51 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.80. 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 Phi Geminorum

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.82000 which gave the calculated distance to Phi Geminorum as 254.42 light years away from Earth or 78.00 parsecs. If you want that in miles, it is about 1,495,639,867,445,374.06, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 14.66000 which put Phi Geminorum at a distance of 222.49 light years or 68.21 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.

Using the 2007 distance, the star is roughly 14,069,224.40 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,460.00 Parsecs or 24,331.79 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Phi Geminorum

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736202,724,855.69
Speed of Sound (Mach 1)767.269194,463,081.12
Concorde (Mach 2)1,534.5497,231,413.83
New Horizons Probe33,0004,521,378.60
Speed of Light670,616,629.00222.49

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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Additional Phi Geminorum Facts and Figures

Visual Facts

Primary / Proper / Traditional NamePhi Geminorum
Alternative NamesPhi Gem, HD 64145, HIP 38538, HR 3067, 83 Geminorum, 83 Gem, BD+27 1499
Spectral TypeA3V
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
GalaxyMilky Way
Absolute Magnitude 0.51 / 0.80
Visual / Apparent Magnitude4.97
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)07h 53m 29.84
Declination (Dec.)+26° 45` 57.1
Galactic Latitude24.70233775 degrees
Galactic Longitude194.19019766 degrees
1997 Distance from Earth12.82000 Parallax (milliarcseconds)
 254.42 Light Years
 78.00 Parsecs
2007 Distance from Earth14.66000 Parallax (milliarcseconds)
 222.49 Light Years
 68.21 Parsecs
 14,069,224.40 Astronomical Units
Galacto-Centric Distance24,331.79 Light Years / 7,460.00 Parsecs
Proper Motion Dec.-30.10000 ± 0.42000 milliarcseconds/year
Proper Motion RA.-34.69000 ± 0.73000 milliarcseconds/year
B-V Index0.09
Radial Velocity8.00000 ± 2.80 km/s
Semi-Major Axis8013.0000000
Stellar Luminosity (Lsun)40.8100000
Orbital Period (Days)581.72800
Argument Of Periastron0.00000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)2.95
Effective Temperature8,538 Kelvin

Sources and Links

SIMBAD SourceLink

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