Universe Guide


Alpha Pyxidis - HD74575 - HIP42828

Alpha Pyxidis is a blue giant star that can be located in the constellation of Pyxis. Alpha Pyxidis is the Bayer Classification for the star. HIP42828 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74575.

Location of Alpha Pyxidis

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 Alpha Pyxidis, the location is 08h 43m 35.55 and -33d11`11.1 .

Proper Motion of Alpha Pyxidis

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 010.43 ± 000.09 towards the north and -014.27 ± 000.14 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Alpha Pyxidis

Alpha Pyxidis has a spectral type of B1.5III. This means the star is a blue giant 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 15,433 Kelvin.

Alpha Pyxidis has been calculated as 6.22 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,330,324.07.km.

Alpha Pyxidis Apparent and Absolute Magnitudes

Alpha Pyxidis has an apparent magnitude of 3.68 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 -3.39 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.47. 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 Alpha Pyxidis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.86 which gave the calculated distance to Alpha Pyxidis as 844.98 light years away from Earth or 259.07 parsecs. It would take a spaceship travelling at the speed of light, 844.98 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 3.71 which put Alpha Pyxidis at a distance of 879.15 light years or 269.54 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.

Alpha Pyxidis Facts

Alternative Names

Bayer DesignationAlpha Pyxidis
Hipparcos Library I.D.42828
Henry Draper Designation74575

Visual Facts

Star Typegiant star
Absolute Magnitude-3.39 / -3.47
Apparent Magnitude3.68
Right Ascension (R.A.)08h 43m 35.55
Declination (Dec.)-33d11`11.1
1997 Distance from Earth3.86 Parallax (milliarcseconds)
 844.98 Light Years
 259.07 Parsecs
2007 Revised Distance from Earth3.71 Parallax (milliarcseconds)
 879.15 Light Years
 269.54 Parsecs
Proper Motion Dec.10.43 ± 0.09 milliarcseconds/year
Proper Motion RA.-14.27 ± 0.14 milliarcseconds/year
B-V Index-0.18
Spectral TypeB1.5III
Colour(B) blue

Estimated Facts

Radius (x the Sun)6.22
Calculated Effective Temperature15,433 Kelvin

Sources and Links

SIMBAD SourceLink

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