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HD 21693

HD 21693 Facts

HD 21693's Alternative Names

HIP16085 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD21693.

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

Location of HD 21693

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 HD 21693, the location is 03h 27m 12.20 and -58° 19` 26.1 .

Radial Velocity and Proper Motion of HD 21693

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 94.39 ± 0.43 milliarcseconds/year towards the north and 249.89 ± 0.49 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 39.40 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.

HD 21693 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 0.69 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of HD 21693

HD 21693 Colour and Temperature

HD 21693 has a spectral type of G8V. This means the star is a yellow main sequence star. The star has a B-V Colour Index of 0.76 which means the star's temperature is about 5,391 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu at being .

HD 21693 Radius

Radius has been calculated as being 0.89 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 619,435.59.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 0.89. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is 0.01 with an error value of 0.03 Fe/H with the Sun has a value of 1 to put it into context.

HD 21693 Apparent and Absolute Magnitudes

HD 21693 has an apparent magnitude of 7.95 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 5.40 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.40. 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 HD 21693

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 30.95 which gave the calculated distance to HD 21693 as 105.38 light years away from Earth or 32.31 parsecs. If you want that in miles, it is 70,669,580,364.

In 2007, Hipparcos data was revised with a new parallax of 30.88 which put HD 21693 at a distance of 105.62 light years or 32.38 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 6,678,807.89 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 7,399.00 Parsecs or 24,132.83 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 HD 21693

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)
Walking417,707,632,088.75
Car120590,254,402.96
Airbus A38073696,237,130.92
Speed of Sound (Mach 1)767.26992,315,118.11
Concorde (Mach 2)1,534.5446,157,498.90
New Horizons Probe33,0002,146,379.65
Speed of Light670,616,629.00105.62

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 HD 21693 Facts and Figures

Visual Facts


Primary / Proper / Traditional NameHD 21693
Alternative NamesHD 21693, HIP 16085
Spectral TypeG8V
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type Main Sequence Dwarf Star
ColourYellow
GalaxyMilky Way
ConstellationReticulum
Absolute Magnitude 5.40 / 5.40
Visual / Apparent Magnitude7.95
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)03h 27m 12.20
Declination (Dec.)-58° 19` 26.1
Galactic Latitude-48.73 degrees
Galactic Longitude272.91 degrees
1997 Distance from Earth30.95 Parallax (milliarcseconds)
 105.38 Light Years
 32.31 Parsecs
2007 Distance from Earth30.88 Parallax (milliarcseconds)
 105.62 Light Years
 32.38 Parsecs
 6,678,807.89 Astronomical Units
Galacto-Centric Distance24,132.83 Light Years / 7,399.00 Parsecs
Proper Motion Dec.94.39 ± 0.43 milliarcseconds/year
Proper Motion RA.249.89 ± 0.49 milliarcseconds/year
B-V Index0.76
Radial Velocity39.40 ± 0.20 km/s
Iron Abundance0.01 ± 0.03 Fe/H
Eccentricity0.28
Semi-Major Axis5578.00
Stellar Luminosity (Lsun)0.69

Companions (Multi-Star and Exoplanets) Facts


Exoplanet Count2

Estimated Calculated Facts


Radius (x the Sun)0.89
Effective Temperature5,391 Kelvin

Sources and Links


SIMBAD SourceLink

List of Extrasolar Planets orbiting HD 21693


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
HD 21693 bConfirmed0.004622.6560.2620110.1484
HD 21693 cConfirmed0.005753.8810.2420110.2644

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