Helvetios is a white to yellow main sequence dwarf star that can be located in the constellation of Pegasus. The Id of the star in the Yale Bright Star Catalogue is HR8729. HIP113357 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD217014. Helvetios has alternative name(s), 51 Pegasi , 51 Peg. Helvetios has at least 1 Extrasolar Planets believed to be in orbit around the star.
The star was an obscure planet that people probably never heard of before 1995. It was the first star discovered to have an exoplanet in orbit round it by Swiss astronomers Michel Mayor and Didier Queloz. They nicknamed the planet, Bellerophon which stuck with it but the planet was later renamed Dimidum. Dimidum is latin for half and refers to the fact that the planet is half the mass of Jupiter. Bellerophon was an ancinet greek hero famed for slaying Chimera, a winged creature.
In the same competition, the star 51 Pegasi obtained the name Helvetios. The name Helvetios comes from the tribe that lived in Switzerland during the middle ages. It was meant to honour the fact that the discoverers were Swiss. ref:I.A.U.
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 Helvetios, the location is 22h 57m 27.85 and +20d46`07.3 .
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 060.34 ± 000.16 towards the north and 207.25 ± 000.38 east if we saw them in the horizon.
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 1.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.
Helvetios has a spectral type of G5V. This means the star is a white to yellow main sequence dwarf star. The star has a B-V Colour Index of 0.66 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,689 Kelvin.
Helvetios has been calculated as 1.20 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 834,202.69.km.
The star's metallicity is 0.200000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.
Helvetios has an apparent magnitude of 5.45 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 4.52 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.48. 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 65.10 which gave the calculated distance to Helvetios as 50.10 light years away from Earth or 15.36 parsecs. It would take a spaceship travelling at the speed of light, 50.10 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 64.07 which put Helvetios at a distance of 50.91 light years or 15.61 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 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.
|Short Name||51 Peg|
|Alternative Name(s)||51 Pegasi|
|Hipparcos Library I.D.||113357|
|Yale Bright Star Catalogue (HR) Id||8729|
|Bonner Durchmusterung||BD+19 5036|
|Henry Draper Designation||217014|
|Star Type||main sequence dwarf star|
|Absolute Magnitude||4.52 / 4.48|
|Right Ascension (R.A.)||22h 57m 27.85|
|1997 Distance from Earth||65.10 Parallax (milliarcseconds)|
|50.10 Light Years|
|2007 Revised Distance from Earth||64.07 Parallax (milliarcseconds)|
|50.91 Light Years|
|Proper Motion Dec.||60.34 ± 0.16 milliarcseconds/year|
|Proper Motion RA.||207.25 ± 0.38 milliarcseconds/year|
|Colour||(G) White to Yellow|
|Radius (x the Sun)||1.20|
|Luminosity (x the Sun)||1.0000000|
|Calculated Effective Temperature||5,689 Kelvin|
|Name||Status||Mass (Jupiters)||Orbital Period (Days)||Eccentricity||Discovered||Semi-Major Axis||Periastron||Inclination|
|51 Peg B||Confirmed||0.47||4.231||0.0069||1995||0.052||54.000||80.000|