Universe Guide

HD 7924

HD 7924 Facts

  • HD 7924 is a star that can be located in the constellation of Cassiopeia. The description is based on the spectral class.
  • HD 7924 is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K0) of the star, the star's colour is orange to red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • HD 7924 has at least 3 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 54.83 light years away from us. Distance

HD 7924's Alternative Names

HIP6379 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD7924. The Gliese ID of the star is GL 56.5. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

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+75 58.

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

Location of HD 7924

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 object is compared to the celestial equator and is expressed in degrees. For HD 7924, the location is 01h 21m 59.20 and +76° 42` 37.3 .

Radial Velocity and Proper Motion of HD 7924

Proper Motion

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 -33.28 ± 0.38 milliarcseconds/year towards the north and -34.23 ± 0.46 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -23.40000 km/s with an error of about 1.13 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.

Physical Properties of HD 7924

HD 7924 Colour and Temperature

Based on the star's spectral type of K0 , HD 7924's colour and type is orange to red star. The star has a B-V Colour Index of 0.8 which means the star's temperature is about 5,422 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

HD 7924 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 0.40 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

HD 7924 Radius

HD 7924 estimated radius has been calculated as being 0.66 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 456,046.90.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 0.6554281370980831868971812547. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

HD 7924 Mass

The HD 7924's solar mass is 0.83 times that of our star, the Sun. 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.

HD 7924 Metalicity

The star's metallicity is -0.150000, 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.

HD 7924 Apparent and Absolute Magnitudes

HD 7924 has an apparent magnitude of 7.17 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 6.04 If you used the 2007 Parallax value, you would get an absolute magnitude of 6.04. 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 7924

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 59.46000 which gave the calculated distance to HD 7924 as 54.85 light years away from Earth or 16.82 parsecs. If you want that in miles, it is about 322,442,601,719,121.01, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 59.49000 which put HD 7924 at a distance of 54.83 light years or 16.81 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 3,467,287.23 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 7,409.00 Parsecs or 24,165.44 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to HD 7924

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A38073649,959,116.53
Speed of Sound (Mach 1)767.26947,923,100.98
Concorde (Mach 2)1,534.5423,961,519.26
New Horizons Probe33,0001,114,239.69
Speed of Light670,616,629.0054.83

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 HD 7924 Facts and Figures

Visual Facts

Primary / Proper / Traditional NameHD 7924
Alternative NamesHD 7924, HIP 6379, BD+75 58, Gliese 56.5
Spectral TypeK0
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeStar
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 6.04 / 6.04
Visual / Apparent Magnitude7.17
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)01h 21m 59.20
Declination (Dec.)+76° 42` 37.3
Galactic Latitude13.94573000 degrees
Galactic Longitude124.73577427 degrees
1997 Distance from Earth59.46000 Parallax (milliarcseconds)
 54.85 Light Years
 16.82 Parsecs
2007 Distance from Earth59.49000 Parallax (milliarcseconds)
 54.83 Light Years
 16.81 Parsecs
 3,467,287.23 Astronomical Units
Galacto-Centric Distance24,165.44 Light Years / 7,409.00 Parsecs
Proper Motion Dec.-33.28000 ± 0.38000 milliarcseconds/year
Proper Motion RA.-34.23000 ± 0.46000 milliarcseconds/year
B-V Index0.8
Radial Velocity-23.40000 ± 1.13 km/s
Iron Abundance-0.1400 ± 0.02 Fe/H
Semi-Major Axis7342.0000000
Stellar Luminosity (Lsun)0.4000000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count3

Estimated Calculated Facts

Radius (x the Sun)0.66
Effective Temperature5,422 Kelvin
Mass Compared to the Sun0.83

Sources and Links

SIMBAD SourceLink

List of Extrasolar Planets orbiting HD 7924

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
HD 7924 bConfirmed0.00175.3980.05820090.05664332.000
HD 7924 cConfirmed0.002315.2990.09820150.1134
HD 7924 dConfirmed0.002524.4510.2120150.1551119.000

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