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HK Lyrae - HD173291 - HIP91774

HK Lyrae is a pulsating luminous giant star that can be located in the constellation of Lyra. The star can not be seen by the naked eye, you need a telescope to see it.

HIP91774 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD173291.

HK Lyrae has alternative name(s), HK_Lyr.

Location of HK Lyrae

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 HK Lyrae, the location is 18h 42m 50.00 and +36d57`30.9 .

Physical Properties (Temperature, Radius) of HK Lyrae

HK Lyrae has a spectral type of C5II. This means the star is a luminous giant star. The star has a B-V Colour Index of 3.08 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.

HK Lyrae Apparent and Absolute Magnitudes

HK Lyrae has an apparent magnitude of 7.97 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 -2.71 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 HK Lyrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.73 which gave the calculated distance to HK Lyrae as 4467.99 light years away from Earth or 1369.86 parsecs. It would take a spaceship travelling at the speed of light, 4467.99 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

Variable Type of HK Lyrae

The star is a pulsating Semi-Regular Star which are giants or supergiants of intermediate and late spectral 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. HK Lyrae brightness ranges from a magnitude of 8.000 to a magnitude of 8.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 186.0 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.

HK Lyrae Facts

Alternative Names

Traditional/Proper NameHK Lyrae
Short NameHK Lyr
Hipparcos Library I.D.91774
Bonner DurchmusterungBDD+36 3243
Henry Draper Designation173291

Visual Facts

Star Typeluminous giant star
Visual / Apparent Magnitude7.97
Naked Eye VisibleRequires a 7x50 Binoculars - Ref: Wiki
Right Ascension (R.A.)18h 42m 50.00
Declination (Dec.)+36d57`30.9
Galactic Latitude17.51 degrees
Galactic Longitude66.08 degrees
1997 Distance from Earth0.73 Parallax (milliarcseconds)
 4467.99 Light Years
 1369.86 Parsecs
B-V Index3.08
Radial Velocity-5.00 ± 3.10 km/s
Spectral TypeC5II

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemi-Regular Star which are giants or supergiants of intermediate and late spectral
Mean Variability Period in Days186.000

Estimated Facts

Sources and Links

SIMBAD SourceLink

Related Stars


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