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Ekchusis, Lambda Aquarii, 73 Aquarii, HD216386, HIP112961, HR8698

Ekchusis (Lambda Aquarii) is a red pulsating giant star that can be located in the constellation of Aquarius. Ekchusis is the brightest star in Aquarius based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Lambda Aquarii is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR8698. HIP112961 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD216386. The Id of the star in the Gould Star Catalogue is 185. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Ekchusis has alternative name(s), 73 Aquarii, Hydor , lam Aqr.

Location of Ekchusis

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 Ekchusis, the location is 22h 52m 36.86 and -07d 34` 46.8 .

Proper Motion of Ekchusis

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 33.03 ± 0.47 miliarcseconds/year towards the north and 17.02 ± 0.66 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Ekchusis

Ekchusis has a spectral type of M2IIIvar. This means the star is a red giant star. The star is 7370.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24038.2384528000000000s. The star has a B-V Colour Index of 1.62 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,728 Kelvin.

Ekchusis Radius has been calculated as being 48.30 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 33,608,754.48.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 47.42. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Ekchusis Apparent and Absolute Magnitudes

Ekchusis has an apparent magnitude of 3.73 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 -1.67 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.63. 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 Ekchusis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 8.33 which gave the calculated distance to Ekchusis as 391.55 light years away from Earth or 120.05 parsecs. It would take a spaceship travelling at the speed of light, 391.55 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 8.47 which put Ekchusis at a distance of 385.08 light years or 118.06 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 7,370.00 Parsecs or 24,038.24 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Ekchusis

The star is a pulsating Slow Irregular variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Ekchusis brightness ranges from a magnitude of 3.851 to a magnitude of 3.776 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 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.

Ekchusis Facts

Alternative Names

Traditional/Proper NameEkchusis
Flamsteed Short Name73 Aqr
Short Namelam Aqr
Bayer DesignationLambda Aquarii
Alternative Name(s)73 Aquarii, Hydor
Hipparcos Library I.D.112961
Yale Bright Star Catalogue (HR) Id8698
Bonner DurchmusterungBD-08 5968
Gould I.D.185
Henry Draper Designation216386

Visual Facts

Star Typegiant star
Absolute Magnitude-1.67 / -1.63
Visual / Apparent Magnitude3.73
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 52m 36.86
Declination (Dec.)-07d 34` 46.8
Galactic Latitude-55.73 degrees
Galactic Longitude62.19 degrees
1997 Distance from Earth8.33 Parallax (milliarcseconds)
 391.55 Light Years
 120.05 Parsecs
2007 Revised Distance from Earth8.47 Parallax (milliarcseconds)
 385.08 Light Years
 118.06 Parsecs
Galacto-Centric Distance24,038.24 Light Years / 7,370.00 Parsecs
Proper Motion Dec.33.03 ± 0.47 milliarcseconds/year
Proper Motion RA.17.02 ± 0.66 milliarcseconds/year
B-V Index1.62
Radial Velocity-10.46 ± 0.53 km/s
Spectral TypeM2IIIvar
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.065
Variable Magnitude Range (Brighter - Dimmer)3.776 - 3.851

Estimated Facts

Calculated Effective Temperature3,728 Kelvin

Sources and Links

SIMBAD SourceLink

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