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Chertan (Theta Leonis) - HD97633 - HIP54879 - HR4359

Chertan (Theta Leonis) is a blue main sequence dwarf star that can be located in the constellation of Leo. Theta Leonis is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR4359. HIP54879 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD97633. Chertan has alternative name(s), Chort, 70 Leonis, Coxa , 70 Leo. In Arabic, it is known as Al-Kharat.

Location of Chertan

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 Chertan, the location is 11h 14m 14.44 and +15d25`47.1 .

Proper Motion of Chertan

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 -079.10 ± 000.12 towards the north and -060.31 ± 000.17 east if we saw them in the horizon.

Chertan 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 17.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of Chertan

Chertan has a spectral type of A2V. This means the star is a blue main sequence dwarf star. The star has a B-V Colour Index of 0 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,531 Kelvin.

Chertan has been calculated as 4.02 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,799,718.24.km.

Chertan Apparent and Absolute Magnitudes

Chertan has an apparent magnitude of 3.33 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 -0.35 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.19. 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 Chertan

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 18.36 which gave the calculated distance to Chertan as 177.65 light years away from Earth or 54.47 parsecs. It would take a spaceship travelling at the speed of light, 177.65 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 19.76 which put Chertan at a distance of 165.06 light years or 50.61 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.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Chertan Facts

Alternative Names

Traditional NameChertan
Short Name70 Leo
Arabic NameAl-Kharat
English MeaningThe Rib
Bayer DesignationTheta Leonis
Alternative Name(s)Chort, 70 Leonis, Coxa
Hipparcos Library I.D.54879
Yale Bright Star Catalogue (HR) Id4359
Bonner DurchmusterungBD+16 2234
Henry Draper Designation97633

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude-0.35 / -0.19
Apparent Magnitude3.33
Right Ascension (R.A.)11h 14m 14.44
Declination (Dec.)+15d25`47.1
1997 Distance from Earth18.36 Parallax (milliarcseconds)
 177.65 Light Years
 54.47 Parsecs
2007 Revised Distance from Earth19.76 Parallax (milliarcseconds)
 165.06 Light Years
 50.61 Parsecs
Proper Motion Dec.-79.10 ± 0.12 milliarcseconds/year
Proper Motion RA.-60.31 ± 0.17 milliarcseconds/year
B-V Index0.00
Spectral TypeA2V
Colour(A) blue

Estimated Facts

Radius (x the Sun)4.02
Luminosity (x the Sun)17.0000000
Calculated Effective Temperature9,531 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Chertan in Leo


Chertan (Theta Leonis) Location in Leo

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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