Universe Guide


Deneb Algedi (Delta Capricorni) - HD207098 - HIP107556

Deneb Algedi (Delta Capricorni) is a blue eclipsing binary system subgiant star that can be located in the constellation of Capricornus. Delta Capricorni is the Bayer Classification for the star. HIP107556 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD207098. Deneb Algedi has alternative name(s), del_Cap, 49 Cap. In Arabic, it is known as Dhanab al-Jady.

Location of Deneb Algedi

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 Deneb Algedi, the location is 21h 47m 02.29 and -16d07`35.6 .

Proper Motion of Deneb Algedi

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 -296.70 ± 0.14 miliarcseconds/year towards the north and 261.70 ± 0.19 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Deneb Algedi

Deneb Algedi has a spectral type of A5mF2 (IV). This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.18 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,889 Kelvin.

Deneb Algedi has been calculated as 1.59 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,104,891.09.km.

Deneb Algedi Apparent and Absolute Magnitudes

Deneb Algedi has an apparent magnitude of 2.85 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 2.49 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.48. 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 Deneb Algedi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 84.58 which gave the calculated distance to Deneb Algedi as 38.56 light years away from Earth or 11.82 parsecs. It would take a spaceship travelling at the speed of light, 38.56 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 84.27 which put Deneb Algedi at a distance of 38.70 light years or 11.87 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.

Variable Type of Deneb Algedi

The star is a eclipsing binary system Beta Lyrae (Sheliak) 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. Deneb Algedi brightness ranges from a magnitude of 3.000 to a magnitude of 3.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 1.0 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Deneb Algedi Facts

Alternative Names

Traditional/Proper NameDeneb Algedi
Short Namedel Cap, 49 Cap
Arabic NameDhanab al-Jady
English MeaningTail of the goat
Bayer DesignationDelta Capricorni
Hipparcos Library I.D.107556
Bonner DurchmusterungBD-16 5943
Henry Draper Designation207098

Visual Facts

Star Typesubgiant star
Absolute Magnitude2.49 / 2.48
Apparent Magnitude2.85
Right Ascension (R.A.)21h 47m 02.29
Declination (Dec.)-16d07`35.6
1997 Distance from Earth84.58 Parallax (milliarcseconds)
 38.56 Light Years
 11.82 Parsecs
2007 Revised Distance from Earth84.27 Parallax (milliarcseconds)
 38.70 Light Years
 11.87 Parsecs
Proper Motion Dec.-296.70 ± 0.14 milliarcseconds/year
Proper Motion RA.261.70 ± 0.19 milliarcseconds/year
B-V Index0.18
Spectral TypeA5mF2 (IV)
Colour(A) blue

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Lyrae (Sheliak)
Mean Variability Period in Days1.000

Estimated Facts

Radius (x the Sun)1.59
Calculated Effective Temperature7,889 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
207098-16 5943.0A3.00000261.00000-294.00000A5White

Location of Deneb Algedi in Capricornus

Deneb Algedi (Delta Capricorni) Location in Capricornus

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

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