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HR 8799, HD218396, HIP114189

HR 8799 is a blue main sequence dwarf star that can be located in the constellation of Pegasus. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it. It is calculated at being .060 Billion Years old. This information comes from ExoPlanet. HR 8799 has at least 4 Extrasolar Planets believed to be in orbit around the star.

HR 8799's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR8799. HIP114189 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD218396.

HR 8799 has alternative name(s) :- , V342 Peg.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+20 5278.

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

Location of HR 8799

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 8799, the location is 23h 07m 28.65 and +21° 08` 03.7 .

Proper Motion of HR 8799

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 -49.63 ± 0.45 miliarcseconds/year towards the north and 107.93 ± 0.70 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 us is -12.60000 km/s with an error of about 1.40 km/s .

HR 8799 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 5.25 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, Age, Mass) of HR 8799

HR 8799 has a spectral type of A5V. This means the star is a blue main sequence dwarf star. The star is 7,402.00 Parsecs from the Galactic Centre or terms of Light Years is 24,142.61 s. The star has a B-V Colour Index of 0.25 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,483 Kelvin.

HR 8799 Radius has been calculated as being 1.42 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 989,025.02.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 1.40. 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 1.56 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 -0.470000, 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 0.06 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.

HR 8799 Apparent and Absolute Magnitudes

HR 8799 has an apparent magnitude of 5.97 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 2.96 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.99. 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 8799

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 25.04 which gave the calculated distance to HR 8799 as 130.26 light years away from Earth or 39.94 parsecs. It would take a spaceship travelling at the speed of light, 130.26 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 25.38 which put HR 8799 at a distance of 128.51 light years or 39.40 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 7,402.00 Parsecs or 24,142.61 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*. HR 8799 brightness ranges from a magnitude of 6.063 to a magnitude of 6.005 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 days (variability).

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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HR 8799 Facts

Visual Facts

Primary / Proper / Traditional NameHR 8799
Alternative NamesHD 218396, HIP 114189, HR 8799, BD+20 5278, V342 Peg
Spectral TypeA5V
Multiple Star SystemNo / Unknown
Star Type main sequence Dwarf Star
Colour blue
GalaxyMilky Way
Age0.06 Billion Years Old
Absolute Magnitude2.96 / 2.99
Visual / Apparent Magnitude5.97
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)23h 07m 28.65
Declination (Dec.)+21° 08` 03.7
Galactic Latitude-35.57 degrees
Galactic Longitude92.76 degrees
1997 Distance from Earth25.04 Parallax (milliarcseconds)
 130.26 Light Years
 39.94 Parsecs
2007 Distance from Earth25.38 Parallax (milliarcseconds)
 128.51 Light Years
 39.40 Parsecs
Galacto-Centric Distance24,142.61 Light Years / 7,402.00 Parsecs
Proper Motion Dec.-49.63 ± 0.45 milliarcseconds/year
Proper Motion RA.107.93 ± 0.70 milliarcseconds/year
B-V Index0.25
Radial Velocity-12.60 ± 1.40 km/s
Semi-Major Axis6967.00
Stellar Luminosity (Lsun)5.25

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count4

Variable Star Details

Mean Variability Period in Days0.518
Variable Magnitude Range (Brighter - Dimmer)6.005 - 6.063

Estimated Facts

Calculated Effective Temperature7,483 Kelvin
Mass Compared to the Sun1.56

Sources and Links

SIMBAD SourceLink

List of Extrasolar Planets orbiting HR 8799

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastronInclination
HR 8799 bConfirmed2.0164250.0000.02008682008.000
HR 8799 cConfirmed3.082145.0000.0200842.92008.000
HR 8799 dConfirmed3.041054.0000.120082780.2002008.000
HR 8799 eConfirmed4.018000.000201014.52010.000

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