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HR 7703, HD191408, HIP99461

Primary Facts on HR 7703

  • HR 7703's star type is main sequence dwarf star that can be located in the constellation of Sagittarius. The description is based on the spectral class.
  • HR 7703 is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K2V) of the star, the star's colour is orange to red .
  • 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 19.62 light years away from us.

Information on HR 7703


In the Defiance episode 'Of a Demon in my View', an Omec spaceship is seen receiving a radio transmission from Earth. The scene is set in 1978 and the Omec spaceship is in orbit around a planet in the star system. After receiving the music, the Omec are seen celebrating and then changing course to Earth where they believe the Voltans are now living. In the episode, the star system is referred to as Gliese 783.

HR 7703's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR7703. HIP99461 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD191408. The Gliese ID of the star is GL 783A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 279 G. Sagittarii. There are no stars with a Gould designation in Ursa Major for example.

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

Location of HR 7703

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For HR 7703, the location is 20h 11m 11.61 and -36° 05` 50.6 .

Radial Velocity and Proper Motion of HR 7703

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 -1,574.64 ± 0.13 miliarcseconds/year towards the north and 456.99 ± 0.27 miliarcseconds/year east if we saw them in the horizon.

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -126.90 km/s with an error of about 0.62 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.

HR 7703 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 0.29 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 HR 7703

HR 7703 has a spectral type of K2V. This means the star is a orange to red main sequence dwarf star. The star is 7,395.00 Parsecs from the Galactic Centre or in terms of Light Years is 24,119.78 s. The star has a B-V Colour Index of 0.86 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,141 Kelvin.

HR 7703 Radius has been calculated as being 0.61 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 427,789.08.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 0.61. 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 -0.49 with an error value of 0.01 Fe/H with the Sun has a value of 1 to put it into context.

HR 7703 Apparent and Absolute Magnitudes

HR 7703 has an apparent magnitude of 5.32 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 6.41 If you used the 2007 Parallax value, you would get an absolute magnitude of 6.42. 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 HR 7703

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 165.24 which gave the calculated distance to HR 7703 as 19.74 light years away from Earth or 6.05 parsecs. It would take a spaceship travelling at the speed of light, 19.74 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 166.25 which put HR 7703 at a distance of 19.62 light years or 6.02 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 1,241,705.48 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 7,395.00 Parsecs or 24,119.78 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.

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Additional HR 7703 Facts and Figures

Visual Facts

Primary / Proper / Traditional NameHR 7703
Alternative NamesHD 191408, HIP 99461, HR 7703, 279 G. Sagittarii, Gliese 783A
Spectral TypeK2V
Constellation's Main StarNo
Multiple Star SystemYes
Star Type main sequence Dwarf Star
Colour orange to red
GalaxyMilky Way
Absolute Magnitude 6.41 / 6.42
Visual / Apparent Magnitude5.32
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)20h 11m 11.61
Declination (Dec.)-36° 05` 50.6
Galactic Latitude-30.92 degrees
Galactic Longitude5.24 degrees
1997 Distance from Earth165.24 Parallax (milliarcseconds)
 19.74 Light Years
 6.05 Parsecs
2007 Distance from Earth166.25 Parallax (milliarcseconds)
 19.62 Light Years
 6.02 Parsecs
 1,241,705.48 Astronomical Units
Galacto-Centric Distance24,119.78 Light Years / 7,395.00 Parsecs
Proper Motion Dec.-1574.64 ± 0.13 milliarcseconds/year
Proper Motion RA.456.99 ± 0.27 milliarcseconds/year
B-V Index0.86
Radial Velocity-126.90 ± 0.62 km/s
Iron Abundance-0.49 ± 0.01 Fe/H
Semi-Major Axis6293.00
Stellar Luminosity (Lsun)0.29

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Facts

Calculated Effective Temperature5,141 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear

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