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HD 203857, HIP105637

HD 203857 is a orange to red star that can be located in the constellation of Cygnus. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP105637 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD203857. HD 203857 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of HD 203857

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 203857, the location is 21h 23m 48.39 and +37d21`05.4 .

Proper Motion of HD 203857

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 -7.39 ± 0.29 miliarcseconds/year towards the north and -5.96 ± 0.45 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of HD 203857

HD 203857 has a spectral type of K5. This means the star is a orange to red star. The star is 7375.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24054.5466200000000000s. The star has a B-V Colour Index of 1.47 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,076 Kelvin.

HD 203857 Radius has been calculated as being 27.07 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 18,833,339.43.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 26.94. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

HD 203857 Apparent and Absolute Magnitudes

HD 203857 has an apparent magnitude of 6.46 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 -0.80 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.79. 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 203857

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.54 which gave the calculated distance to HD 203857 as 921.37 light years away from Earth or 282.49 parsecs. It would take a spaceship travelling at the speed of light, 921.37 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 3.55 which put HD 203857 at a distance of 918.77 light years or 281.69 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 7,375.00 Parsecs or 24,054.55 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 203857 Facts

Alternative Names

Traditional/Proper NameHD 203857
Hipparcos Library I.D.105637
Bonner DurchmusterungBD+36 4543
Henry Draper Designation203857

Visual Facts

Star Type star
Absolute Magnitude-0.80 / -0.79
Visual / Apparent Magnitude6.46
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 23m 48.39
Declination (Dec.)+37d21`05.4
Galactic Latitude-9.20 degrees
Galactic Longitude83.60 degrees
1997 Distance from Earth3.54 Parallax (milliarcseconds)
 921.37 Light Years
 282.49 Parsecs
2007 Revised Distance from Earth3.55 Parallax (milliarcseconds)
 918.77 Light Years
 281.69 Parsecs
Galacto-Centric Distance24,054.55 Light Years / 7,375.00 Parsecs
Proper Motion Dec.-7.39 ± 0.29 milliarcseconds/year
Proper Motion RA.-5.96 ± 0.45 milliarcseconds/year
B-V Index1.47
Radial Velocity-6.06 ± 0.21 km/s
Spectral TypeK5
Colour(K) Orange to Red

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature4,076 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


List of Extrasolar Planets orbiting HD 203857


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Hd 203857 BUnconfirmed8.1840.0000.32009

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