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FN Ursae Majoris

FN Ursae Majoris Facts

FN Ursae Majoris's Alternative Names

HIP42068 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD71951.

FN Ursae Majoris has alternative name(s) :- , FN UMa.

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+67 550.

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

Location of FN Ursae Majoris

The location of the variable 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 FN Ursae Majoris, the location is 08h 34m 27.62 and +67° 11` 20.3 .

Proper Motion of FN Ursae Majoris

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 -1.11 ± 0.58 milliarcseconds/year towards the north and 2.93 ± 0.96 milliarcseconds/year east if we saw them in the horizon. . 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 (Colour, Temperature) of FN Ursae Majoris

FN Ursae Majoris Colour and Temperature

FN Ursae Majoris has a spectral type of M.... This means the star is a red variable star. The star has a B-V Colour Index of 1.29 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,404 Kelvin.

FN Ursae Majoris Radius

Radius has been calculated as being 12.68 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 8,824,461.30.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 15.75. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

FN Ursae Majoris Apparent and Absolute Magnitudes

FN Ursae Majoris has an apparent magnitude of 8.35 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 0.04. 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 FN Ursae Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.70 which gave the calculated distance to FN Ursae Majoris as 1208.01 light years away from Earth or 370.37 parsecs. It would take a spaceship travelling at the speed of light, 1208.01 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 2.18 which put FN Ursae Majoris at a distance of 1496.16 light years or 458.72 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 94,617,132.62 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.

Variable Type of FN Ursae Majoris

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. FN Ursae Majoris brightness ranges from a magnitude of 8.700 to a magnitude of 8.290 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 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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Additional FN Ursae Majoris Facts and Figures

Visual Facts

Primary / Proper / Traditional NameFN Ursae Majoris
Alternative NamesHD 71951, HIP 42068, BD+67 550, FN UMa
Spectral TypeM...
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeVariable Star
GalaxyMilky Way
ConstellationUrsa Major
Absolute Magnitude 0.51 / 0.04
Visual / Apparent Magnitude8.35
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)08h 34m 27.62
Declination (Dec.)+67° 11` 20.3
Galactic Latitude34.77 degrees
Galactic Longitude148.09 degrees
1997 Distance from Earth2.70 Parallax (milliarcseconds)
  1208.01 Light Years
 370.37 Parsecs
2007 Distance from Earth2.18 Parallax (milliarcseconds)
 1496.16 Light Years
 458.72 Parsecs
 94,617,132.62 Astronomical Units
Proper Motion Dec.-1.11 ± 0.58 milliarcseconds/year
Proper Motion RA.2.93 ± 0.96 milliarcseconds/year
B-V Index1.29

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeIrregular
Mean Variability Period in Days0.312
Variable Magnitude Range (Brighter - Dimmer)8.290 - 8.700

Estimated Calculated Facts

Radius (x the Sun)15.75
Effective Temperature4,404 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
71951+67 550.0A9.20000-2.000006.00000M.Red

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