Universe Guide

Alpha Pyxidis

Alpha Pyxidis Facts

  • Alpha Pyxidis is a giant star that can be located in the constellation of Pyxis. The description is based on the spectral class.
  • Alpha Pyxidis is a main star of the constellation outline.
  • Based on the spectral type (B1.5III) of the star, the star's colour is blue .
  • Alpha Pyxidis is the 1st brightest star in Pyxis based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 879.15 light years away from us. Distance

Alpha Pyxidis's Alternative Names

Alpha Pyxidis (Alf Pyx) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR3468. 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.

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

Location of Alpha Pyxidis

The location of the giant star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For Alpha Pyxidis, the location is 08h 43m 35.55 and -33° 11` 11.1 .

Radial Velocity and Proper Motion of Alpha Pyxidis

Proper Motion

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 10.43 ± 0.09 milliarcseconds/year towards the north and -14.27 ± 0.14 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 15.30000 km/s with an error of about 2.70 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Alpha Pyxidis

Alpha Pyxidis Temperature and Colour

Based on the star's spectral type of B1.5III , Alpha Pyxidis's colour and type is blue giant star. The star has a B-V Colour Index of -0.18 which means the star's temperature is about 15,433 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Alpha Pyxidis 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 6,959.36 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Alpha Pyxidis Radius

Alpha Pyxidis estimated radius has been calculated as being 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. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 6.4570888188266055239539985156. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Alpha Pyxidis Iron Abundance

Alpha Pyxidis Iron Abundance is -0.13 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

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 3.86000 which gave the calculated distance to Alpha Pyxidis as 844.98 light years away from Earth or 259.07 parsecs. If you want that in miles, it is about 4,967,320,867,832,686.78, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 3.71000 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.

Using the 2007 distance, the star is roughly 55,596,228.48 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,474.00 Parsecs or 24,377.45 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Alpha Pyxidis

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736801,049,741.01
Speed of Sound (Mach 1)767.269768,404,053.06
Concorde (Mach 2)1,534.54384,201,525.79
New Horizons Probe33,00017,865,836.65
Speed of Light670,616,629.00879.15

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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Additional Alpha Pyxidis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameAlpha Pyxidis
Alternative NamesAlf Pyx, HD 74575, HIP 42828, HR 3468
Spectral TypeB1.5III
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star TypeGiant Star
GalaxyMilky Way
Absolute Magnitude -3.39 / -3.47
Visual / Apparent Magnitude3.68
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)08h 43m 35.55
Declination (Dec.)-33° 11` 11.1
Galactic Latitude5.76960267 degrees
Galactic Longitude254.99312719 degrees
1997 Distance from Earth3.86000 Parallax (milliarcseconds)
 844.98 Light Years
 259.07 Parsecs
2007 Distance from Earth3.71000 Parallax (milliarcseconds)
 879.15 Light Years
 269.54 Parsecs
 55,596,228.48 Astronomical Units
Galacto-Centric Distance24,377.45 Light Years / 7,474.00 Parsecs
Proper Motion Dec.10.43000 ± 0.09000 milliarcseconds/year
Proper Motion RA.-14.27000 ± 0.14000 milliarcseconds/year
B-V Index-0.18
Radial Velocity15.30000 ± 2.70 km/s
Iron Abundance-0.1300 ± 9.99 Fe/H
Semi-Major Axis7939.0000000
Stellar Luminosity (Lsun)6959.3600000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)6.46
Effective Temperature15,433 Kelvin

Sources and Links

SIMBAD SourceLink

Location of Alpha Pyxidis in Pyxis

Alpha Pyxidis Location in Pyxis

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

Pyxis Main Stars

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