Universe Guide

HomeFactsConstellationsFornax

HD 20782, HIP15527

HD 20782 is a white to yellow main sequence dwarf star that can be located in the constellation of Fornax. The star can not be seen by the naked eye, you need a telescope to see it. The star has an estimated age of 9.70 Billion of Years but could be as young as 7.40 to 12.30 according to Hipparcos.

HIP15527 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD20782. HD 20782 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of HD 20782

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 20782, the location is 03h 20m 03.35 and -28d51`14.1 .

Proper Motion of HD 20782

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 -65.92 ± 0.46 miliarcseconds/year towards the north and 349.33 ± 0.62 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Age, Mass, Radius) of HD 20782

HD 20782 has a spectral type of G3V. This means the star is a white to yellow main sequence dwarf star. The star is 7414.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24181.7503241600000000s. The star has a B-V Colour Index of 0.63 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,789 Kelvin.

HD 20782 Radius has been calculated as being 1.13 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 783,674.59.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.11. 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 1.00 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 -0.050000, 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 stars age according to Hipparcos data files put the star at an age of about 9.70 Billion years old but could be between 7.40 and 12.30 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

HD 20782 Apparent and Absolute Magnitudes

HD 20782 has an apparent magnitude of 7.36 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 4.58 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.61. 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 20782

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 27.76 which gave the calculated distance to HD 20782 as 117.49 light years away from Earth or 36.02 parsecs. It would take a spaceship travelling at the speed of light, 117.49 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 28.15 which put HD 20782 at a distance of 115.87 light years or 35.52 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.

The star's Galacto-Centric Distance is 7,414.00 Parsecs or 24,181.75 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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 20782 Facts

Alternative Names

Traditional/Proper NameHD 20782
Hipparcos Library I.D.15527
Henry Draper Designation20782

Visual Facts

Star Typemain sequence dwarf star
Age9.70 Billion Years Old
Age Range7.40 - 12.30 Billion Years Old
Absolute Magnitude4.58 / 4.61
Visual / Apparent Magnitude7.36
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)03h 20m 03.35
Declination (Dec.)-28d51`14.1
Galactic Latitude-57.28 degrees
Galactic Longitude224.80 degrees
1997 Distance from Earth27.76 Parallax (milliarcseconds)
 117.49 Light Years
 36.02 Parsecs
2007 Revised Distance from Earth28.15 Parallax (milliarcseconds)
 115.87 Light Years
 35.52 Parsecs
Galacto-Centric Distance24,181.75 Light Years / 7,414.00 Parsecs
Proper Motion Dec.-65.92 ± 0.46 milliarcseconds/year
Proper Motion RA.349.33 ± 0.62 milliarcseconds/year
B-V Index0.63
Radial Velocity40.70 ± 0.99 km/s
Iron Abundance-0.04 ± 0.02 Fe/H
Spectral TypeG3V
Colour(G) White to Yellow

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature5,789 Kelvin
Mass Compared to the Sun1.00
Metallicity-0.05000

Sources and Links

SIMBAD SourceLink

Related Stars


List of Extrasolar Planets orbiting HD 20782


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Hd 20782 BConfirmed1.9591.9000.9720061.381148.000

Add a Comment


Name:
Email: (Optional)
Comment: