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R Crateris, HD95384, HIP53809

R Crateris is a red pulsating giant star that can be located in the constellation of Crater. R Crateris is the brightest star in Crater based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP53809 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD95384.

R Crateris has alternative name(s), R Crt.

Location of R Crateris

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 R Crateris, the location is 11h 00m 33.87 and -18d19`29.6 .

Proper Motion of R Crateris

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 -2.06 ± 0.62 miliarcseconds/year towards the north and -28.79 ± 0.95 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of R Crateris

R Crateris has a spectral type of M7/8III. This means the star is a red giant star. The star has a B-V Colour Index of 1.19 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,507 Kelvin.

R Crateris Radius has been calculated as being 55.10 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 38,338,931.66.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 6.47. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

R Crateris Apparent and Absolute Magnitudes

R Crateris has an apparent magnitude of 8.95 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 -2.78 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.87. 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 R Crateris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.45 which gave the calculated distance to R Crateris as 7248.07 light years away from Earth or 2222.22 parsecs. It would take a spaceship travelling at the speed of light, 7248.07 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 3.83 which put R Crateris at a distance of 851.60 light years or 261.10 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 Crateris

The star is a pulsating Semiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity 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 Crateris brightness ranges from a magnitude of 7.953 to a magnitude of 7.652 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 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.

R Crateris Facts

Alternative Names

Traditional/Proper NameR Crateris
Short NameR Crt
Hipparcos Library I.D.53809
Bonner DurchmusterungBD-17 3281
Henry Draper Designation95384

Visual Facts

Star Typegiant star
Absolute Magnitude-2.78 / 1.87
Visual / Apparent Magnitude8.95
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)11h 00m 33.87
Declination (Dec.)-18d19`29.6
Galactic Latitude37.20 degrees
Galactic Longitude269.27 degrees
1997 Distance from Earth0.45 Parallax (milliarcseconds)
 7248.07 Light Years
 2222.22 Parsecs
2007 Revised Distance from Earth3.83 Parallax (milliarcseconds)
 851.60 Light Years
 261.10 Parsecs
Proper Motion Dec.-2.06 ± 0.62 milliarcseconds/year
Proper Motion RA.-28.79 ± 0.95 milliarcseconds/year
B-V Index1.19
Radial Velocity21.70 ± 999.00 km/s
Spectral TypeM7/8III
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity
Mean Variability Period in Days0.322
Variable Magnitude Range (Brighter - Dimmer)7.652 - 7.953

Estimated Facts

Calculated Effective Temperature4,507 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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
95384-17 3281.0A-15.000007.00000M3Red
95383-17 3279.0B9.9000011.000003.00000F2Yellow/White1866

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