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AI Fornacis, HD20729, HIP15479

AI Fornacis is a red pulsating giant star that can be located in the constellation of Fornax. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

AI Fornacis's Alternative Names

HIP15479 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD20729.

AI Fornacis has alternative name(s) :- , AI For.

More details on star alternative names can be found at Star Names.

Location of AI Fornacis

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 AI Fornacis, the location is 03h 19m 34.90 and -24° 07` 22.2 .

Proper Motion of AI Fornacis

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 -23.75 ± 0.26 miliarcseconds/year towards the north and 5.47 ± 0.39 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 15.00000 km/s with an error of about 4.30 km/s .

Physical Properties (Colour, Temperature) of AI Fornacis

AI Fornacis has a spectral type of M1III. This means the star is a red giant star. The star is 7535.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24576.4079704000000000s. The star has a B-V Colour Index of 1.66 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,608 Kelvin.

AI Fornacis Radius has been calculated as being 64.33 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 44,758,536.76.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 53.50. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

AI Fornacis Apparent and Absolute Magnitudes

AI Fornacis has an apparent magnitude of 5.63 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 -2.15 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.75. 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 AI Fornacis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.78 which gave the calculated distance to AI Fornacis as 1173.25 light years away from Earth or 359.71 parsecs. It would take a spaceship travelling at the speed of light, 1173.25 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 3.34 which put AI Fornacis at a distance of 976.54 light years or 299.40 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 7,535.00 Parsecs or 24,576.41 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 AI Fornacis

The star is a pulsating Semi-Regular Star which are giants or supergiants of intermediate and late spectral 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. AI Fornacis brightness ranges from a magnitude of 5.747 to a magnitude of 5.651 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.

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AI Fornacis Facts

Visual Facts

Alternative NamesHD 20729, HIP 15479, AI For
Star TypeGiant Star
GalaxyMilky Way
Absolute Magnitude-2.15 / -1.75
Visual / Apparent Magnitude5.63
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)03h 19m 34.90
Declination (Dec.)-24° 07` 22.2
Galactic Latitude-56.59 degrees
Galactic Longitude216.21 degrees
1997 Distance from Earth2.78 Parallax (milliarcseconds)
 1173.25 Light Years
 359.71 Parsecs
2007 Revised Distance from Earth3.34 Parallax (milliarcseconds)
 976.54 Light Years
 299.40 Parsecs
Galacto-Centric Distance24,576.41 Light Years / 7,535.00 Parsecs
Proper Motion Dec.-23.75 ± 0.26 milliarcseconds/year
Proper Motion RA.5.47 ± 0.39 milliarcseconds/year
B-V Index1.66
Radial Velocity15.00 ± 4.30 km/s
Semi-Major Axis6562.00
Spectral TypeM1III
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemi-Regular Star which are giants or supergiants of intermediate and late spectral
Mean Variability Period in Days0.077
Variable Magnitude Range (Brighter - Dimmer)5.651 - 5.747

Estimated Facts

Calculated Effective Temperature3,608 Kelvin

Sources and Links

SIMBAD SourceLink

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