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HD 28678 - HIP21109

HD 28678 is a orange to red star that can be located in the constellation of Taurus. The star can not be seen by the naked eye, you need a telescope to see it. It is calculated at being 1.800 Billion Years old. This information comes from ExoPlanet.

HIP21109 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD28678. HD 28678 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of HD 28678

The location of the star in the galaxy 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 star is compared to the celestial equator and is expressed in degrees. For HD 28678, the location is 04h 31m 25.45 and +04d34`31.1 .

Proper Motion of HD 28678

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 -8.82 ± 0.63 miliarcseconds/year towards the north and 4.03 ± 0.93 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Age, Mass, Radius) of HD 28678

HD 28678 has a spectral type of K0. This means the star is a orange to red star. The star has a B-V Colour Index of 1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,973 Kelvin.

HD 28678 Radius has been calculated as being 4.48 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,119,815.57.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 6.02. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 2.00 times that of the Sun's. 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.

The star's metallicity is -0.110000, 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.

The star is believed to be about 1.80 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.

HD 28678 Apparent and Absolute Magnitudes

HD 28678 has an apparent magnitude of 8.38 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 2.24 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.60. 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 28678

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.92 which gave the calculated distance to HD 28678 as 550.95 light years away from Earth or 168.92 parsecs. It would take a spaceship travelling at the speed of light, 550.95 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 4.41 which put HD 28678 at a distance of 739.60 light years or 226.76 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.

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.

HD 28678 Facts

Alternative Names

Traditional/Proper NameHD 28678
Hipparcos Library I.D.21109
Bonner DurchmusterungBDD+04 704
Henry Draper Designation28678

Visual Facts

Star Type star
Age1.80 Billion Years Old
Absolute Magnitude2.24 / 1.60
Visual / Apparent Magnitude8.38
Naked Eye VisibleRequires a 7x50 Binoculars - Ref: Wiki
Right Ascension (R.A.)04h 31m 25.45
Declination (Dec.)+04d34`31.1
Galactic Latitude-28.20 degrees
Galactic Longitude190.82 degrees
1997 Distance from Earth5.92 Parallax (milliarcseconds)
 550.95 Light Years
 168.92 Parsecs
2007 Revised Distance from Earth4.41 Parallax (milliarcseconds)
 739.60 Light Years
 226.76 Parsecs
Proper Motion Dec.-8.82 ± 0.63 milliarcseconds/year
Proper Motion RA.4.03 ± 0.93 milliarcseconds/year
B-V Index1.00
Radial Velocity61.47 ± 0.25 km/s
Spectral TypeK0
Colour(K) Orange to Red

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature4,973 Kelvin
Mass Compared to the Sun2.00
Metallicity-0.11000

Sources and Links

SIMBAD SourceLink

Related Stars


List of Extrasolar Planets orbiting HD 28678


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Hd 28678 BConfirmed1.7387.1000.16820111.24131.000

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