Universe Guide

Beta Arae

Beta Arae Facts

  • Beta Arae is a supergiant star that can be located in the constellation of Ara. The description is based on the spectral class.
  • Beta Arae is a main star of the constellation outline.
  • Based on the spectral type (K3Ib-II) 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.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 645.87 light years away from us. Distance

Beta Arae's Alternative Names

Beta Arae (Bet Ara) 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 HR6461. HIP85258 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD157244.

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

Location of Beta Arae

The location of the supergiant 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 Beta Arae, the location is 17h 25m 18.00 and -55° 31` 47.4 .

Radial Velocity and Proper Motion of Beta Arae

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 -25.24 ± 0.37 milliarcseconds/year towards the north and -8.51 ± 0.64 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 -0.30000 km/s with an error of about 0.30 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 Beta Arae

Beta Arae Colour and Temperature

Based on the star's spectral type of K3Ib-II , Beta Arae's colour and type is orange to red supergiant star. The star has a B-V Colour Index of 1.47 which means the star's temperature is about 4,076 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Beta Arae 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 6,327.55 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Beta Arae Radius

Beta Arae estimated radius has been calculated as being 93.43 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 65,006,044.79.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 100.10846240215657713527183816. 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.

Beta Arae Apparent and Absolute Magnitudes

Beta Arae has an apparent magnitude of 2.84 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 -3.49 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.64. 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 Beta Arae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.41000 which gave the calculated distance to Beta Arae as 602.89 light years away from Earth or 184.84 parsecs. If you want that in miles, it is about 3,544,164,451,238,666.63, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 5.05000 which put Beta Arae at a distance of 645.87 light years or 198.02 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 40,844,272.33 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 7,227.00 Parsecs or 23,571.82 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 Beta Arae

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 A380736588,493,426.86
Speed of Sound (Mach 1)767.269564,510,181.14
Concorde (Mach 2)1,534.54282,254,722.70
New Horizons Probe33,00013,125,186.73
Speed of Light670,616,629.00645.87

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 Beta Arae Facts and Figures

Visual Facts

Primary / Proper / Traditional NameBeta Arae
Alternative NamesBet Ara, HD 157244, HIP 85258, HR 6461
Spectral TypeK3Ib-II
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star TypeLuminous Giant Star less luminour Supergiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude -3.49 / -3.64
Visual / Apparent Magnitude2.84
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)17h 25m 18.00
Declination (Dec.)-55° 31` 47.4
Galactic Latitude-11.01284401 degrees
Galactic Longitude335.36724888 degrees
1997 Distance from Earth5.41000 Parallax (milliarcseconds)
 602.89 Light Years
 184.84 Parsecs
2007 Distance from Earth5.05000 Parallax (milliarcseconds)
 645.87 Light Years
 198.02 Parsecs
 40,844,272.33 Astronomical Units
Galacto-Centric Distance23,571.82 Light Years / 7,227.00 Parsecs
Proper Motion Dec.-25.24000 ± 0.37000 milliarcseconds/year
Proper Motion RA.-8.51000 ± 0.64000 milliarcseconds/year
B-V Index1.47
Radial Velocity-0.30000 ± 0.30 km/s
Semi-Major Axis6662.0000000
Stellar Luminosity (Lsun)6327.5500000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)100.11
Effective Temperature4,076 Kelvin

Sources and Links

SIMBAD SourceLink

Location of Beta Arae in Ara

Beta Arae Location in Ara

The map was generated using Night Vision, an awesome free application by Brian Simpson.

Ara Main Stars

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