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R Muscae, HD110311, HIP61981, HR4820

R Muscae is a blue to white pulsating supergiant star that can be located in the constellation of Musca. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

R Muscae's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR4820. HIP61981 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD110311.

R Muscae has alternative name(s) :- , R Mus.

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

Location of R Muscae

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For R Muscae, the location is 12h 42m 05.03 and -69° 24` 27.2 .

Proper Motion of R Muscae

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 -1.96 ± 0.37 miliarcseconds/year towards the north and -4.85 ± 0.50 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 3.80000 km/s with an error of about 2.90 km/s .

Physical Properties (Colour, Temperature) of R Muscae

R Muscae has a spectral type of F7Ib. This means the star is a blue to white supergiant star. The star has a B-V Colour Index of 0.75 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,535 Kelvin.

R Muscae Radius has been calculated as being 32.86 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 22,865,337.42.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 34.73. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

R Muscae Apparent and Absolute Magnitudes

R Muscae has an apparent magnitude of 6.31 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 -2.55 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.67. 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 R Muscae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.69 which gave the calculated distance to R Muscae as 1929.96 light years away from Earth or 591.72 parsecs. It would take a spaceship travelling at the speed of light, 1929.96 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 1.60 which put R Muscae at a distance of 2038.52 light years or 625 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.

Variable Type of R Muscae

The star is a pulsating Delta Cepheid variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. R Muscae brightness ranges from a magnitude of 6.902 to a magnitude of 6.023 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 7.5 days (variability).

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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R Muscae Facts

Visual Facts


Primary / Proper / Traditional NameR Muscae
Alternative NamesR Mus, HD 110311, HIP 61981, HR 4820, R Mus
Spectral TypeF7Ib
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
Colour blue to white
GalaxyMilky Way
ConstellationMusca
Absolute Magnitude-2.55 / -2.67
Visual / Apparent Magnitude6.31
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)12h 42m 05.03
Declination (Dec.)-69° 24` 27.2
Galactic Latitude-6.55 degrees
Galactic Longitude302.10 degrees
1997 Distance from Earth1.69 Parallax (milliarcseconds)
 1929.96 Light Years
 591.72 Parsecs
2007 Distance from Earth1.60 Parallax (milliarcseconds)
 2038.52 Light Years
 625 Parsecs
Proper Motion Dec.-1.96 ± 0.37 milliarcseconds/year
Proper Motion RA.-4.85 ± 0.50 milliarcseconds/year
B-V Index0.75
Radial Velocity3.80 ± 2.90 km/s

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days7.511
Variable Magnitude Range (Brighter - Dimmer)6.023 - 6.902

Estimated Facts


Calculated Effective Temperature5,535 Kelvin

Sources and Links


SIMBAD SourceLink

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