Universe Guide
Search

Eta Arae

Eta Arae Facts

  • Eta Arae is a giant star that can be located in the constellation of Ara. The description is based on the spectral class.
  • Eta Arae is a main star of the constellation outline.
  • Based on the spectral type (K5III) 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 299.23 light years away from us. Distance

Eta Arae's Alternative Names

Eta Arae (Eta 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 HR6229. HIP82363 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD151249.

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

Location of Eta Arae

The location of the giant 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 Eta Arae, the location is 16h 49m 47.11 and -59° 02` 28.7 .

Radial Velocity and Proper Motion of Eta 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 -24.91 ± 0.10 milliarcseconds/year towards the north and 39.73 ± 0.20 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 9.00000 km/s with an error of about 0.70 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 Eta Arae

Eta Arae Temperature and Colour

Based on the star's spectral type of K5III , Eta Arae's colour and type is orange to red giant star. The star has a B-V Colour Index of 1.56 which means the star's temperature is about 3,871 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Eta 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 774.10 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Eta Arae Radius

Eta Arae estimated radius has been calculated as being 35.10 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 24,420,394.73.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 33.517164695242135252781688868. 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.

Eta Arae Iron Abundance

Eta Arae Iron Abundance is -0.33 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

Eta Arae Apparent and Absolute Magnitudes

Eta Arae has an apparent magnitude of 3.77 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 -1.14 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.04. 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 Eta Arae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 10.41000 which gave the calculated distance to Eta Arae as 313.32 light years away from Earth or 96.06 parsecs. If you want that in miles, it is about 1,841,890,901,925,888.69, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 10.90000 which put Eta Arae at a distance of 299.23 light years or 91.74 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 18,922,601.47 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 7,322.00 Parsecs or 23,881.68 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 Eta 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)
Walking450,167,153,473.92
Car1201,672,238,449.13
Airbus A380736272,647,573.23
Speed of Sound (Mach 1)767.269261,536,193.82
Concorde (Mach 2)1,534.54130,767,926.48
New Horizons Probe33,0006,080,867.09
Speed of Light670,616,629.00299.23

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.

Hide Explanations
Show GridLines

Additional Eta Arae Facts and Figures

Visual Facts


Primary / Proper / Traditional NameEta Arae
Alternative NamesEta Ara, HD 151249, HIP 82363, HR 6229
Spectral TypeK5III
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeGiant Star
ColourOrange to Red
GalaxyMilky Way
ConstellationAra
Absolute Magnitude -1.14 / -1.04
Visual / Apparent Magnitude3.77
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)16h 49m 47.11
Declination (Dec.)-59° 02` 28.7
Galactic Latitude-9.16374950 degrees
Galactic Longitude329.63515467 degrees
1997 Distance from Earth10.41000 Parallax (milliarcseconds)
 313.32 Light Years
 96.06 Parsecs
2007 Distance from Earth10.90000 Parallax (milliarcseconds)
 299.23 Light Years
 91.74 Parsecs
 18,922,601.47 Astronomical Units
Galacto-Centric Distance23,881.68 Light Years / 7,322.00 Parsecs
Proper Motion Dec.-24.91000 ± 0.10000 milliarcseconds/year
Proper Motion RA.39.73000 ± 0.20000 milliarcseconds/year
B-V Index1.56
Radial Velocity9.00000 ± 0.70 km/s
Iron Abundance-0.3300 ± 0.06 Fe/H
Eccentricity0.16670
Semi-Major Axis8373.0000000
Stellar Luminosity (Lsun)774.1000000

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)33.52
Effective Temperature3,871 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
151249-58 6906.4A3.7000041.00000-31.00000K5Orange
B13.500001942

Ara Main Stars


Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

   
x
This website is using cookies. More info. That's Fine