Universe Guide


Albali (Epsilon Aquarii) - HD198001 - HIP102618 - HR7950

Albali (Epsilon Aquarii) is a blue main sequence dwarf star that can be located in the constellation of Aquarius. Epsilon Aquarii is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR7950. HIP102618 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD198001. The Id of the star in the Gould Star Catalogue is 8. 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. Albali has alternative name(s), 2 Aquarii , 2 Aqr.

Location of Albali

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 Albali, the location is 20h 47m 40.53 and -09d29`44.5 .

Proper Motion of Albali

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 -034.77 ± 000.10 towards the north and 033.98 ± 000.21 east if we saw them in the horizon.

Albali 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 20.0000000 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 Albali

Albali has a spectral type of A1V. 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.

Albali has been calculated as 4.23 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,945,204.17.km.

Albali Apparent and Absolute Magnitudes

Albali has an apparent magnitude of 3.78 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 -0.46 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.24. 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 Albali

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 14.21 which gave the calculated distance to Albali as 229.53 light years away from Earth or 70.37 parsecs. It would take a spaceship travelling at the speed of light, 229.53 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 15.70 which put Albali at a distance of 207.75 light years or 63.69 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.

Albali Facts

Alternative Names

Traditional NameAlbali
Short Name2 Aqr
Bayer DesignationEpsilon Aquarii
Alternative Name(s)2 Aquarii
Hipparcos Library I.D.102618
Yale Bright Star Catalogue (HR) Id7950
Bonner DurchmusterungBD-10 5506
Gould I.D.8
Henry Draper Designation198001

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude-0.46 / -0.24
Apparent Magnitude3.78
Right Ascension (R.A.)20h 47m 40.53
Declination (Dec.)-09d29`44.5
1997 Distance from Earth14.21 Parallax (milliarcseconds)
 229.53 Light Years
 70.37 Parsecs
2007 Revised Distance from Earth15.70 Parallax (milliarcseconds)
 207.75 Light Years
 63.69 Parsecs
Proper Motion Dec.-34.77 ± 0.10 milliarcseconds/year
Proper Motion RA.33.98 ± 0.21 milliarcseconds/year
B-V Index0.00
Spectral TypeA1V
Colour(A) blue

Estimated Facts

Radius (x the Sun)4.23
Luminosity (x the Sun)20.0000000
Calculated Effective Temperature9,531 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Albali in Aquarius

Albali (Epsilon Aquarii) Location in Aquarius

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

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