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PU Aurigae

PU Aurigae Facts

PU Aurigae's Alternative Names

HIP24738 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD34269.

PU Aurigae has alternative name(s) :- , PU Aur.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+42 1239.

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

Location of PU Aurigae

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 PU Aurigae, the location is 05h 18m 15.68 and +42° 47` 31.9 .

Radial Velocity and Proper Motion of PU Aurigae

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 -30.61 ± 0.19 milliarcseconds/year towards the north and 17.98 ± 0.33 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 -38.41 km/s with an error of about 1.02 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.

PU Aurigae 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 428.61 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of PU Aurigae

PU Aurigae Colour and Temperature

PU Aurigae has a spectral type of M4III. This means the star is a red giant star. The star has a B-V Colour Index of 1.49 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,007 Kelvin.

PU Aurigae Radius

Radius has been calculated as being 32.01 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 22,272,032.23.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 26.02. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

PU Aurigae Apparent and Absolute Magnitudes

PU Aurigae has an apparent magnitude of 5.55 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 -1.09 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.64. 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 PU Aurigae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.70 which gave the calculated distance to PU Aurigae as 693.96 light years away from Earth or 212.77 parsecs. If you want that in miles, it is 3,311,547,245,221,785.55.

In 2007, Hipparcos data was revised with a new parallax of 5.79 which put PU Aurigae at a distance of 563.32 light years or 172.71 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 35,623,746.46 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 7,566.00 Parsecs or 24,677.52 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Time to Travel to PU Aurigae

A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

If you were to drive there at about 120 m.p.h. in a car with an infinity engine so you didn't have to pull over for petrol, it would take you 33,996,090,533,120.76 hours or 3,880,832,252.64 years.

At the time of writing, the fastest probe so far created is the New Horizon probe which is travelling at a speed of 33,000 m.p.h. If the probe was travelling to PU Aurigae then it would take 123,622,147,393.17 hours / 14,112,117.28 years to get there. Speed Ref: N.A.S.A.

It would to take a spaceship journey travelling at the speed of light, 693.96 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

Variable Type of PU Aurigae

The star is a pulsating Slow Irregular 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. PU Aurigae brightness ranges from a magnitude of 5.681 to a magnitude of 5.438 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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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Additional PU Aurigae Facts and Figures

Visual Facts


Primary / Proper / Traditional NamePU Aurigae
Alternative NamesHD 34269, HIP 24738, BD+42 1239, PU Aur
Spectral TypeM4III
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeGiant Star
ColourRed
GalaxyMilky Way
ConstellationAuriga
Absolute Magnitude -1.09 / -0.64
Visual / Apparent Magnitude5.55
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 18m 15.68
Declination (Dec.)+42° 47` 31.9
Galactic Latitude2.95 degrees
Galactic Longitude165.38 degrees
1997 Distance from Earth4.70 Parallax (milliarcseconds)
 693.96 Light Years
 212.77 Parsecs
2007 Distance from Earth5.79 Parallax (milliarcseconds)
 563.32 Light Years
 172.71 Parsecs
 35,623,746.46 Astronomical Units
Galacto-Centric Distance24,677.52 Light Years / 7,566.00 Parsecs
Proper Motion Dec.-30.61 ± 0.19 milliarcseconds/year
Proper Motion RA.17.98 ± 0.33 milliarcseconds/year
B-V Index1.49
Radial Velocity-38.41 ± 1.02 km/s
Eccentricity0.26
Semi-Major Axis6379.00
Stellar Luminosity (Lsun)428.61

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.205
Variable Magnitude Range (Brighter - Dimmer)5.438 - 5.681

Estimated Calculated Facts


Radius (x the Sun)26.02
Effective Temperature4,007 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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