Universe Guide


GJ 3021, HD1237, HIP1292

GJ 3021 is a white to yellow main sequence dwarf star that can be located in the constellation of Hydrus. GJ 3021 is the brightest star in Hydrus based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP1292 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD1237. GJ 3021 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of GJ 3021

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 GJ 3021, the location is 00h 16m 11.24 and -79d51`03.7 .

Proper Motion of GJ 3021

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 -56.74 ± 0.27 miliarcseconds/year towards the north and 433.92 ± 0.31 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of GJ 3021

GJ 3021 has a spectral type of G6V. This means the star is a white to yellow main sequence dwarf star. The star is 7392.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24109.9943884800000000s. The star has a B-V Colour Index of 0.7 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,563 Kelvin.

GJ 3021 Radius has been calculated as being 0.85 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 592,539.20.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.85. 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 0.07 with an error value of 0.01 Fe/H with the Sun has a value of 1 to put it into context.

GJ 3021 Apparent and Absolute Magnitudes

GJ 3021 has an apparent magnitude of 6.59 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 5.36 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.37. 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 GJ 3021

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 56.76 which gave the calculated distance to GJ 3021 as 57.46 light years away from Earth or 17.62 parsecs. It would take a spaceship travelling at the speed of light, 57.46 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 57.15 which put GJ 3021 at a distance of 57.07 light years or 17.50 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 7,392.00 Parsecs or 24,109.99 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.

GJ 3021 Facts

Alternative Names

Traditional/Proper NameGJ 3021
Hipparcos Library I.D.1292
Henry Draper Designation1237

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude5.36 / 5.37
Visual / Apparent Magnitude6.59
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)00h 16m 11.24
Declination (Dec.)-79d51`03.7
Galactic Latitude-37.14 degrees
Galactic Longitude304.87 degrees
1997 Distance from Earth56.76 Parallax (milliarcseconds)
 57.46 Light Years
 17.62 Parsecs
2007 Revised Distance from Earth57.15 Parallax (milliarcseconds)
 57.07 Light Years
 17.50 Parsecs
Galacto-Centric Distance24,109.99 Light Years / 7,392.00 Parsecs
Proper Motion Dec.-56.74 ± 0.27 milliarcseconds/year
Proper Motion RA.433.92 ± 0.31 milliarcseconds/year
B-V Index0.70
Radial Velocity-2.10 ± 0.20 km/s
Iron Abundance0.07 ± 0.01 Fe/H
Spectral TypeG6V
Colour(G) White to Yellow

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature5,563 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

List of Extrasolar Planets orbiting GJ 3021

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Gliese 3021 BConfirmed3.37133.7100.51120000.49291.000

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