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Nu2 Draconis (25 Draconis) Star Facts

Nu2 Draconis Facts

  • Nu2 Draconis is a multiple star system that can be located in the constellation of Draco. The description is based on the spectral class.
  • Nu2 Draconis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (Am) 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 99.44 light years away from us. Distance

Nu2 Draconis's Alternative Names

Nu2 Draconis (Nu.02 Dra) 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 HR6555. HIP85829 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD159560.

Nu2 Draconis has alternative name(s) :- Kuma2.

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 25 Draconis. The Flamsteed name can be shortened to 25 Dra.

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+55 1945.

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

Location of Nu2 Draconis

The location of the multiple star system 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 Nu2 Draconis, the location is 17h 32m 15.88 and +55° 10` 22.1 .

Radial Velocity and Proper Motion of Nu2 Draconis

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 62.43 ± 0.18 milliarcseconds/year towards the north and 142.65 ± 0.18 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 -16.00000 km/s with an error of about 0.70 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 Nu2 Draconis

Nu2 Draconis Temperature and Colour

Based on the star's spectral type of Am , Nu2 Draconis's colour and type is blue - white multiple star system. The star has a B-V Colour Index of 0.27 which means the star's temperature is about 6,943 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Nu2 Draconis 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 8.87 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Nu2 Draconis Radius

Nu2 Draconis estimated radius has been calculated as being 2.11 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,466,458.05.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 2.0979016305950745313601126824. 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.

Nu2 Draconis Apparent and Absolute Magnitudes

Nu2 Draconis has an apparent magnitude of 4.86 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 2.43 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.44. 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 Nu2 Draconis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 32.64000 which gave the calculated distance to Nu2 Draconis as 99.93 light years away from Earth or 30.64 parsecs. If you want that in miles, it is about 587,451,033,542,238.15, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 32.80000 which put Nu2 Draconis at a distance of 99.44 light years or 30.49 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 6,288,970.12 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 7,397.00 Parsecs or 24,126.30 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 Nu2 Draconis

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)
Walking416,671,529,396.94
Car120555,717,646.56
Airbus A38073690,606,138.03
Speed of Sound (Mach 1)767.26986,913,608.64
Concorde (Mach 2)1,534.5443,456,747.68
New Horizons Probe33,0002,020,791.44
Speed of Light670,616,629.0099.44

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 Nu2 Draconis Facts and Figures

Visual Facts


Primary / Proper / Traditional NameNu2 Draconis
Alternative NamesNu.02 Dra, Kuma2, HD 159560, HIP 85829, HR 6555, 25 Draconis, 25 Dra, BD+55 1945
Spectral TypeAm
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeMultiple Star System
ColourBlue
GalaxyMilky Way
ConstellationDraco
Absolute Magnitude 2.43 / 2.44
Visual / Apparent Magnitude4.86
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)17h 32m 15.88
Declination (Dec.)+55° 10` 22.1
Galactic Latitude33.12198959 degrees
Galactic Longitude83.01919140 degrees
1997 Distance from Earth32.64000 Parallax (milliarcseconds)
 99.93 Light Years
 30.64 Parsecs
2007 Distance from Earth32.80000 Parallax (milliarcseconds)
 99.44 Light Years
 30.49 Parsecs
 6,288,970.12 Astronomical Units
Galacto-Centric Distance24,126.30 Light Years / 7,397.00 Parsecs
Proper Motion Dec.62.43000 ± 0.18000 milliarcseconds/year
Proper Motion RA.142.65000 ± 0.18000 milliarcseconds/year
B-V Index0.27
Radial Velocity-16.00000 ± 0.70 km/s
Eccentricity0.14190
Semi-Major Axis8524.0000000
Stellar Luminosity (Lsun)8.8700000
Associated / Clustered StarsKuma

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)2.10
Effective Temperature6,943 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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