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31 Aquilae - HD182572 - HIP95447

31 Aquilae is a white to yellow subgiant star that can be located in the constellation of Aquila. HIP95447 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD182572. 31 Aquilae has alternative name(s), 31 Aquilae , 31 Aql.

Location of 31 Aquilae

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 31 Aquilae, the location is 19h 24m 57.77 and +11d56`34.3 .

Proper Motion of 31 Aquilae

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 642.49 ± 000.15 towards the north and 721.02 ± 000.26 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 31 Aquilae

31 Aquilae has a spectral type of G8IVvar. This means the star is a white to yellow subgiant star. The star has a B-V Colour Index of 0.76 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,391 Kelvin.

31 Aquilae has been calculated as 1.50 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,042,334.82.km.

31 Aquilae Apparent and Absolute Magnitudes

31 Aquilae has an apparent magnitude of 5.17 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 4.27 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.26. 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 31 Aquilae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 66.01 which gave the calculated distance to 31 Aquilae as 49.41 light years away from Earth or 15.15 parsecs. It would take a spaceship travelling at the speed of light, 49.41 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 65.89 which put 31 Aquilae at a distance of 49.50 light years or 15.18 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.

31 Aquilae Facts

Alternative Names

Traditional Name31 Aquilae
Short Name31 Aql
Alternative Name(s)31 Aquilae
Hipparcos Library I.D.95447
Bonner DurchmusterungBD+11 3833
Henry Draper Designation182572

Visual Facts

Star Typesubgiant star
Absolute Magnitude4.27 / 4.26
Apparent Magnitude5.17
Right Ascension (R.A.)19h 24m 57.77
Declination (Dec.)+11d56`34.3
1997 Distance from Earth66.01 Parallax (milliarcseconds)
 49.41 Light Years
 15.15 Parsecs
2007 Revised Distance from Earth65.89 Parallax (milliarcseconds)
 49.50 Light Years
 15.18 Parsecs
Proper Motion Dec.642.49 ± 0.15 milliarcseconds/year
Proper Motion RA.721.02 ± 0.26 milliarcseconds/year
B-V Index0.76
Spectral TypeG8IVvar
Colour(G) White to Yellow

Estimated Facts

Radius (x the Sun)1.50
Calculated Effective Temperature5,391 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
182572+11 3833.0A5.20000723.00000640.00000G5Yellow
231345+11 3834.0B8.7000028.00000-87.00000G0Yellow1909
C10.600001909

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