Universe Guide

PR Serpentis

PR Serpentis Facts

PR Serpentis's Alternative Names

HIP76822 is the reference name for the star in the Hipparcos Star Catalogue.

PR Serpentis has alternative name(s) :- , PR Ser.

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+23 2846.

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

Location of PR Serpentis

The location of the variable 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 PR Serpentis, the location is 15h 41m 05.24 and +23° 21` 06.7 .

Proper Motion of PR Serpentis

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 -4.06 ± 0.74 milliarcseconds/year towards the north and -5.89 ± 1.20 milliarcseconds/year east if we saw them in the horizon. . 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 (Colour, Temperature) of PR Serpentis

PR Serpentis Colour and Temperature

PR Serpentis has a spectral type of M2. This means the star is a red variable star. The star has a B-V Colour Index of 1.55 which means the star's temperature is about 3,903 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu at being .

PR Serpentis Radius

Radius has been calculated as being 16.91 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 11,764,858.35.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 9.38. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

PR Serpentis Apparent and Absolute Magnitudes

PR Serpentis has an apparent magnitude of 9.43 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 0.41 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.69. 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 PR Serpentis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.57 which gave the calculated distance to PR Serpentis as 2077.47 light years away from Earth or 636.94 parsecs. If you want that in miles, it is 1,393,185,928,249.

In 2007, Hipparcos data was revised with a new parallax of 2.83 which put PR Serpentis at a distance of 1152.52 light years or 353.36 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 72,885,224.06 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.

Travel Time to PR Serpentis

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 A3807361,050,134,615.84
Speed of Sound (Mach 1)767.2691,007,337,814.06
Concorde (Mach 2)1,534.54503,668,250.59
New Horizons Probe33,00023,421,184.16
Speed of Light670,616,629.001,152.52
PR Serpentis brightness ranges from a magnitude of 9.624 to a magnitude of 9.416 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 PR Serpentis Facts and Figures

Visual Facts

Primary / Proper / Traditional NamePR Serpentis
Alternative NamesHIP 76822, BD+23 2846, PR Ser
Spectral TypeM2
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeVariable Star
GalaxyMilky Way
Absolute Magnitude 0.41 / 1.69
Visual / Apparent Magnitude9.43
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)15h 41m 05.24
Declination (Dec.)+23° 21` 06.7
Galactic Latitude51.63 degrees
Galactic Longitude36.97 degrees
1997 Distance from Earth1.57 Parallax (milliarcseconds)
 2077.47 Light Years
 636.94 Parsecs
2007 Distance from Earth2.83 Parallax (milliarcseconds)
 1152.52 Light Years
 353.36 Parsecs
 72,885,224.06 Astronomical Units
Proper Motion Dec.-4.06 ± 0.74 milliarcseconds/year
Proper Motion RA.-5.89 ± 1.20 milliarcseconds/year
B-V Index1.55

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Mean Variability Period in Days0.156
Variable Magnitude Range (Brighter - Dimmer)9.416 - 9.624

Estimated Calculated Facts

Radius (x the Sun)9.38
Effective Temperature3,903 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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