Universe Guide

24 Ursae Majoris

24 Ursae Majoris Facts

  • 24 Ursae Majoris is a eclipsing binary sys subgiant star that can be located in the constellation of Ursa Major. The description is based on the spectral class.
  • 24 Ursae Majoris is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G4III-IV) of the star, the star's colour is yellow .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • It is calculated at being 4.604 Billion Years old. This information comes from ExoPlanet.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 104.14 light years away from us. Distance

24 Ursae Majoris's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR3771. HIP46977 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD82210. The Gliese ID of the star is GL 355.1. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

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

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 24 Ursae Majoris. The Flamsteed name can be shortened to 24 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+70 565.

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

Location of 24 Ursae Majoris

The location of the subgiant 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 24 Ursae Majoris, the location is 09h 34m 28.97 and +69° 49` 48.6 .

Radial Velocity and Proper Motion of 24 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 77.25 ± 0.13 milliarcseconds/year towards the north and -63.84 ± 0.19 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 -27.00000 km/s with an error of about 0.20 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 24 Ursae Majoris

24 Ursae Majoris Colour and Temperature

Based on the star's spectral type of G4III-IV , 24 Ursae Majoris's colour and type is yellow subgiant star. The star has a B-V Colour Index of 0.78 which means the star's temperature is about 5,337 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

24 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 15.77 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

24 Ursae Majoris Radius

24 Ursae Majoris estimated radius has been calculated as being 4.37 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,039,302.22.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 4.3081336594895069561749646940. 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.

24 Ursae Majoris Mass

The 24 Ursae Majoris's solar mass is 1.23 times that of our star, the Sun. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

24 Ursae Majoris Metalicity

The star's metallicity is -0.250000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

24 Ursae Majoris Estimated Age

The star is believed to be about 4.60 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.

24 Ursae Majoris Apparent and Absolute Magnitudes

24 Ursae Majoris has an apparent magnitude of 4.54 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 1.99 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.02. 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 24 Ursae Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 30.89000 which gave the calculated distance to 24 Ursae Majoris as 105.59 light years away from Earth or 32.37 parsecs. If you want that in miles, it is about 620,724,053,154,457.38, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 31.32000 which put 24 Ursae Majoris at a distance of 104.14 light years or 31.93 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 6,585,989.37 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 24 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)
Airbus A38073694,888,608.35
Speed of Sound (Mach 1)767.26991,021,552.73
Concorde (Mach 2)1,534.5445,510,717.05
New Horizons Probe33,0002,116,303.51
Speed of Light670,616,629.00104.14

Variable Type of 24 Ursae Majoris

The star is a eclipsing binary sys RS Canum Venaticorum 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. 24 Ursae Majoris brightness ranges from a magnitude of 4.717 to a magnitude of 4.672 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 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 24 Ursae Majoris Facts and Figures

Visual Facts

Primary / Proper / Traditional Name24 Ursae Majoris
Alternative NamesD Uma, DK Ursae Majoris, HD 82210, HIP 46977, HR 3771, 24 Uma, BD+70 565, Gliese 355.1, DK UMa
Spectral TypeG4III-IV
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeSubgiant Star
GalaxyMilky Way
ConstellationUrsa Major
Age4.60 Billion Years Old
Absolute Magnitude 1.99 / 2.02
Visual / Apparent Magnitude4.54
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)09h 34m 28.97
Declination (Dec.)+69° 49` 48.6
Galactic Latitude38.93065753 degrees
Galactic Longitude142.54891787 degrees
1997 Distance from Earth30.89000 Parallax (milliarcseconds)
 105.59 Light Years
 32.37 Parsecs
2007 Distance from Earth31.32000 Parallax (milliarcseconds)
 104.14 Light Years
 31.93 Parsecs
 6,585,989.37 Astronomical Units
Galacto-Centric Distance24,201.32 Light Years / 7,420.00 Parsecs
Proper Motion Dec.77.25000 ± 0.13000 milliarcseconds/year
Proper Motion RA.-63.84000 ± 0.19000 milliarcseconds/year
B-V Index0.78
Radial Velocity-27.00000 ± 0.20 km/s
Iron Abundance-0.2500 ± 9.99 Fe/H
Semi-Major Axis8497.0000000
Stellar Luminosity (Lsun)15.7700000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEclipsing binary sys
Variable Star TypeRS Canum Venaticorum
Mean Variability Period in Days0.034
Variable Magnitude Range (Brighter - Dimmer)4.672 - 4.717

Estimated Calculated Facts

Radius (x the Sun)4.31
Effective Temperature5,337 Kelvin
Mass Compared to the Sun1.23

Sources and Links

SIMBAD SourceLink

Related Stars

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