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Rho Octantis, HD137333, HIP76996, HR5729

Rho Octantis is a blue main sequence dwarf star that can be located in the constellation of Octans. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Rho Octantis's Alternative Names

Rho Octantis is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5729. HIP76996 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD137333.

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

Location of Rho Octantis

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 Rho Octantis, the location is 15h 43m 16.10 and -84° 27` 55.8 .

Proper Motion of Rho Octantis

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 95.52 ± 0.19 miliarcseconds/year towards the north and 137.34 ± 0.23 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -11.00000 km/s with an error of about 10.00 km/s .

Rho Octantis 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 21.9100000 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Rho Octantis

Rho Octantis has a spectral type of A2V. This means the star is a blue main sequence dwarf star. The star is 7363.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24015.4070187200000000s. The star has a B-V Colour Index of 0.11 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,375 Kelvin.

Rho Octantis Radius has been calculated as being 2.27 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,582,719.54.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.25. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Rho Octantis Apparent and Absolute Magnitudes

Rho Octantis has an apparent magnitude of 5.57 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 1.45 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.47. 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 Rho Octantis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.02 which gave the calculated distance to Rho Octantis as 217.15 light years away from Earth or 66.58 parsecs. It would take a spaceship travelling at the speed of light, 217.15 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 15.12 which put Rho Octantis at a distance of 215.72 light years or 66.14 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 star's Galacto-Centric Distance is 7,363.00 Parsecs or 24,015.41 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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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Rho Octantis Facts

Visual Facts

Alternative NamesHD 137333, HIP 76996, HR 5729
Star Type main sequence Dwarf Star
GalaxyMilky Way
Absolute Magnitude1.45 / 1.47
Visual / Apparent Magnitude5.57
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 43m 16.10
Declination (Dec.)-84° 27` 55.8
Galactic Latitude-23.02 degrees
Galactic Longitude307.03 degrees
1997 Distance from Earth15.02 Parallax (milliarcseconds)
 217.15 Light Years
 66.58 Parsecs
2007 Revised Distance from Earth15.12 Parallax (milliarcseconds)
 215.72 Light Years
 66.14 Parsecs
Galacto-Centric Distance24,015.41 Light Years / 7,363.00 Parsecs
Proper Motion Dec.95.52 ± 0.19 milliarcseconds/year
Proper Motion RA.137.34 ± 0.23 milliarcseconds/year
B-V Index0.11
Radial Velocity-11.00 ± 10.00 km/s
Semi-Major Axis15642.00
Stellar Luminosity (Lsun)21.91
Spectral TypeA2V
Colour(A) blue

Estimated Facts

Calculated Effective Temperature8,375 Kelvin

Sources and Links

SIMBAD SourceLink

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