Universe Guide


RY Draconis, HD112559, HIP63152

RY Draconis is a pulsating very luminous supergiant star that can be located in the constellation of Draco. The star can not be seen by the naked eye, you need a telescope to see it.

HIP63152 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD112559.

RY Draconis has alternative name(s), RY Dra.

Location of RY Draconis

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 RY Draconis, the location is 12h 56m 25.89 and +65d59`39.9 .

Proper Motion of RY Draconis

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 -9.83 ± 0.47 miliarcseconds/year towards the north and 13.34 ± 0.59 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Temperature, Radius) of RY Draconis

RY Draconis has a spectral type of C7I. This means the star is a supergiant star. The star has a B-V Colour Index of 3.26 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 0 Kelvin. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

RY Draconis Apparent and Absolute Magnitudes

RY Draconis has an apparent magnitude of 6.63 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 -1.81 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.54. 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 RY Draconis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.05 which gave the calculated distance to RY Draconis as 1591.04 light years away from Earth or 487.80 parsecs. It would take a spaceship travelling at the speed of light, 1591.04 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 2.32 which put RY Draconis at a distance of 1405.88 light years or 431.03 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 RY Draconis

The star is a pulsating Slow Irregular 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. RY Draconis brightness ranges from a magnitude of 6.973 to a magnitude of 6.197 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.7 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.

RY Draconis Facts

Alternative Names

Traditional/Proper NameRY Draconis
Short NameRY Dra
Hipparcos Library I.D.63152
Bonner DurchmusterungBD+66 780
Henry Draper Designation112559

Visual Facts

Star Typesupergiant star
Absolute Magnitude-1.81 / -1.54
Visual / Apparent Magnitude6.63
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)12h 56m 25.89
Declination (Dec.)+65d59`39.9
Galactic Latitude51.13 degrees
Galactic Longitude122.12 degrees
1997 Distance from Earth2.05 Parallax (milliarcseconds)
 1591.04 Light Years
 487.80 Parsecs
2007 Revised Distance from Earth2.32 Parallax (milliarcseconds)
 1405.88 Light Years
 431.03 Parsecs
Proper Motion Dec.-9.83 ± 0.47 milliarcseconds/year
Proper Motion RA.13.34 ± 0.59 milliarcseconds/year
B-V Index3.26
Radial Velocity-20.00 ± 7.40 km/s
Spectral TypeC7I

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.727
Variable Magnitude Range (Brighter - Dimmer)6.197 - 6.973

Estimated Facts

Sources and Links

SIMBAD SourceLink

Related Stars

Add a Comment

Email: (Optional)