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PU Puppis, HD61429, HIP37173, HR2944

PU Puppis is a blue eclipsing binary system subgiant star that can be located in the constellation of Puppis. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

PU Puppis's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR2944. HIP37173 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD61429.

PU Puppis has alternative name(s) :- , PU Pup.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 128 G. Puppis. There are no stars with a Gould designation in Ursa Major for example.

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

Location of PU Puppis

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For PU Puppis, the location is 07h 38m 18.05 and -25° 21` 53.2 .

Proper Motion of PU Puppis

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 -7.42 ± 0.18 miliarcseconds/year towards the north and -3.03 ± 0.26 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 41.00000 km/s with an error of about 7.40 km/s .

PU Puppis 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 716.88 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 Puppis

PU Puppis has a spectral type of B8IV. This means the star is a blue subgiant star. The star is 7,494.00 Parsecs from the Galactic Centre or terms of Light Years is 24,442.68 s. The star has a B-V Colour Index of -0.1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,677 Kelvin.

PU Puppis Radius has been calculated as being 4.45 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,095,561.99.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 4.99. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

PU Puppis Apparent and Absolute Magnitudes

PU Puppis has an apparent magnitude of 4.69 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 -1.45 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.70. 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 Puppis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.92 which gave the calculated distance to PU Puppis as 550.95 light years away from Earth or 168.92 parsecs. It would take a spaceship travelling at the speed of light, 550.95 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 5.27 which put PU Puppis at a distance of 618.91 light years or 189.75 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 7,494.00 Parsecs or 24,442.68 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 PU Puppis

The star is a eclipsing binary system Beta Lyrae (Sheliak) 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 Puppis brightness ranges from a magnitude of 4.689 to a magnitude of 4.628 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 2.6 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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PU Puppis Facts

Visual Facts


Primary / Proper / Traditional NamePU Puppis
Alternative NamesM Pup, HD 61429, HIP 37173, HR 2944, 128 G. Puppis, PU Pup
Spectral TypeB8IV
Multiple Star SystemYes
Star TypeSubgiant Star
Colour blue
GalaxyMilky Way
ConstellationPuppis
Absolute Magnitude-1.45 / -1.70
Visual / Apparent Magnitude4.69
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)07h 38m 18.05
Declination (Dec.)-25° 21` 53.2
Galactic Latitude-1.84 degrees
Galactic Longitude240.65 degrees
1997 Distance from Earth5.92 Parallax (milliarcseconds)
 550.95 Light Years
 168.92 Parsecs
2007 Distance from Earth5.27 Parallax (milliarcseconds)
 618.91 Light Years
 189.75 Parsecs
Galacto-Centric Distance24,442.68 Light Years / 7,494.00 Parsecs
Proper Motion Dec.-7.42 ± 0.18 milliarcseconds/year
Proper Motion RA.-3.03 ± 0.26 milliarcseconds/year
B-V Index-0.10
Radial Velocity41.00 ± 7.40 km/s
Eccentricity0.20
Semi-Major Axis6133.00
Stellar Luminosity (Lsun)716.88

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEclipsing binary system
Variable Star TypeBeta Lyrae (Sheliak)
Mean Variability Period in Days2.582
Variable Magnitude Range (Brighter - Dimmer)4.628 - 4.689

Estimated Facts


Calculated Effective Temperature11,677 Kelvin

Sources and Links


SIMBAD SourceLink

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
61429-25 4828.2A5.30000-9.00000-10.00000B8Blue/White
B5.500001926

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