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Toliman (Alpha Centauri B) Star Facts

Toliman Facts

  • Toliman is a main sequence star that can be located in the constellation of Centaurus. The description is based on the spectral class.
  • Toliman is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K1V) of the star, the star's colour is orange to red .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • It is calculated at being 6.500 Billion Years old. This information comes from ExoPlanet.
  • Toliman has at least 1 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 4.09 light years away from us. Distance

Toliman's Alternative Names

Alpha Centauri B (Alf Cen B) 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 HR5460. HIP71681 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD128621. The Gliese ID of the star is GL 559B. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Toliman has alternative name(s) :- , Alf Cen B.

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 364 G. Centauri. There are no stars with a Gould designation in Ursa Major for example.

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

Location of Toliman

The location of the main sequence 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 Toliman, the location is 14h 39m 39.39 and -60° 50` 22.1 .

Radial Velocity and Proper Motion of Toliman

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 802.98 ± 14.24 milliarcseconds/year towards the north and -3,614.39 ± 25.90 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 -18.60000 km/s with an error of about 1.64 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 Toliman

Toliman Temperature and Colour

Based on the star's spectral type of K1V , Toliman's colour and type is orange to red main sequence star. The star's effective temperature is 5,178 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

Toliman 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 0.58 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Toliman Radius

Toliman estimated radius has been calculated as being 0.88 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 614,334.90.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 0.8164302603448353352143456787. 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.

Toliman Iron Abundance

Toliman Iron Abundance is 0.21 with an error value of 0.02 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

Toliman Estimated Age

The star is believed to be about 6.50 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.

Toliman Apparent and Absolute Magnitudes

Toliman has an apparent magnitude of 1.35 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 5.70 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.87. 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 Toliman

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 742.12000 which gave the calculated distance to Toliman as 4.40 light years away from Earth or 1.35 parsecs. If you want that in miles, it is about 25,865,951,642,007.88, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 796.92000 which put Toliman at a distance of 4.09 light years or 1.25 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 257,829.21 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 7,399.00 Parsecs or 24,132.83 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 Toliman

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)
Walking4685,705,503.15
Car12022,856,850.11
Airbus A3807363,726,660.34
Speed of Sound (Mach 1)767.2693,574,785.39
Concorde (Mach 2)1,534.541,787,390.37
New Horizons Probe33,00083,115.82
Speed of Light670,616,629.004.09

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 Toliman Facts and Figures

Visual Facts


Primary / Proper / Traditional NameToliman
Alternative NamesAlpha Centauri B, Alf Cen B, HD 128621, HIP 71681, HR 5460, 364 G. Centauri, Gliese 559B, Alf Cen B
Spectral TypeK1V
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourOrange to Red
GalaxyMilky Way
ConstellationCentaurus
Age6.50 Billion Years Old
Absolute Magnitude 5.70 / 5.87
Visual / Apparent Magnitude1.35
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)14h 39m 39.39
Declination (Dec.)-60° 50` 22.1
Galactic Latitude-0.68704397 degrees
Galactic Longitude315.73732627 degrees
1997 Distance from Earth742.12000 Parallax (milliarcseconds)
 4.40 Light Years
 1.35 Parsecs
2007 Distance from Earth796.92000 Parallax (milliarcseconds)
 4.09 Light Years
 1.25 Parsecs
 257,829.21 Astronomical Units
Galacto-Centric Distance24,132.83 Light Years / 7,399.00 Parsecs
Proper Motion Dec.802.98000 ± 14.24000 milliarcseconds/year
Proper Motion RA.-3614.39000 ± 25.90000 milliarcseconds/year
B-V Index0.9
Radial Velocity-18.60000 ± 1.64 km/s
Iron Abundance0.2100 ± 0.02 Fe/H
Eccentricity0.16230
Semi-Major Axis8622.0000000
Stellar Luminosity (Lsun)0.5800000
Associated / Clustered StarsProxima Centauri
Rigil Kentaurus

Companions (Multi-Star and Exoplanets) Facts


Exoplanet Count1

Estimated Calculated Facts


Radius (x the Sun)0.82
Effective Temperature5,052 Kelvin

Sources and Links


SIMBAD SourceLink

List of Extrasolar Planets orbiting Toliman


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
alf Cen B bConfirmed0.00033.2360.020120.04

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Comments and Questions

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davidSunday, 24th September 2017 2:25:45 PM
what's the absolute & apparent lightning?
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