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AW Ursae Majoris

AW Ursae Majoris Facts

  • AW Ursae Majoris is a eclipsing variable star that can be located in the constellation of Ursa Major. The description is based on the spectral class.
  • AW Ursae Majoris is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (F1) of the star, the star's colour is yellow to white .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • The star has an estimated age of 2.00 Billion of Years but could be as young as 1.90 to 2.20 according to Hipparcos.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 224.79 light years away from us. Distance

AW Ursae Majoris's Alternative Names

HIP56109 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD99946.

AW Ursae Majoris has alternative name(s) :- AW UMa, AW 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+30 2163.

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

Location of AW 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 AW Ursae Majoris, the location is 11h 30m 04.37 and +29° 57` 54.4 .

Radial Velocity and Proper Motion of AW Ursae Majoris

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 -197.66 ± 0.48 milliarcseconds/year towards the north and -83.85 ± 0.86 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 -17.00000 km/s with an error of about 1.57 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 AW Ursae Majoris

AW Ursae Majoris Temperature and Colour

Based on the star's spectral type of F1 , AW Ursae Majoris's colour and type is yellow to white variable star. The star has a B-V Colour Index of 0.37 which means the star's temperature is about 6,501 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

AW Ursae Majoris 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 6.83 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

AW Ursae Majoris Radius

AW Ursae Majoris estimated radius has been calculated as being 2.03 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,410,587.43.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 2.1130825724732790353318174977. 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.

AW Ursae Majoris Iron Abundance

AW Ursae Majoris Iron Abundance is -0.26 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

AW Ursae Majoris Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 2.00 Billion years old but could be between 1.90 and 2.20 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

AW Ursae Majoris Apparent and Absolute Magnitudes

AW Ursae Majoris has an apparent magnitude of 6.90 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 2.80 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.71. 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 AW Ursae Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.13000 which gave the calculated distance to AW Ursae Majoris as 215.57 light years away from Earth or 66.09 parsecs. If you want that in miles, it is about 1,267,255,271,697,190.81, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 14.51000 which put AW Ursae Majoris at a distance of 224.79 light years or 68.92 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 14,215,671.39 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 7,420.00 Parsecs or 24,201.32 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 AW Ursae Majoris

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)
Walking437,686,978,008.23
Car1201,256,232,600.27
Airbus A380736204,820,532.65
Speed of Sound (Mach 1)767.269196,473,351.63
Concorde (Mach 2)1,534.5498,236,547.78
New Horizons Probe33,0004,568,118.55
Speed of Light670,616,629.00224.79

Variable Type of AW Ursae Majoris

The star is a eclipsing W Ursae Majoris/Cont 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. AW Ursae Majoris brightness ranges from a magnitude of 7.157 to a magnitude of 6.913 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.4 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 AW Ursae Majoris Facts and Figures

Visual Facts


Primary / Proper / Traditional NameAW Ursae Majoris
Alternative NamesAW UMa, HD 99946, HIP 56109, BD+30 2163, AW UMa
Spectral TypeF1
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeVariable Star
ColourYellow - White
GalaxyMilky Way
ConstellationUrsa Major
Age2.00 Billion Years Old
Age Range1.90 - 2.20 Billion Years Old
Absolute Magnitude 2.80 / 2.71
Visual / Apparent Magnitude6.90
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)11h 30m 04.37
Declination (Dec.)+29° 57` 54.4
Galactic Latitude71.93264961 degrees
Galactic Longitude199.10346432 degrees
1997 Distance from Earth15.13000 Parallax (milliarcseconds)
 215.57 Light Years
 66.09 Parsecs
2007 Distance from Earth14.51000 Parallax (milliarcseconds)
 224.79 Light Years
 68.92 Parsecs
 14,215,671.39 Astronomical Units
Galacto-Centric Distance24,201.32 Light Years / 7,420.00 Parsecs
Proper Motion Dec.-197.66000 ± 0.48000 milliarcseconds/year
Proper Motion RA.-83.85000 ± 0.86000 milliarcseconds/year
B-V Index0.37
Radial Velocity-17.00000 ± 1.57 km/s
Iron Abundance-0.2600 ± 9.99 Fe/H
Eccentricity0.44310
Semi-Major Axis4662.0000000
Stellar Luminosity (Lsun)6.8300000

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEclipsing
Variable Star TypeW Ursae Majoris/Cont
Mean Variability Period in Days0.439
Variable Magnitude Range (Brighter - Dimmer)6.913 - 7.157

Estimated Calculated Facts


Radius (x the Sun)2.11
Effective Temperature6,501 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
99946+30 2163.0A7.00000-85.00000-202.00000F0Yellow/White
+30 2164.0B9.00000-99.00000-215.000001875

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