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V636 Scorpii, HD156979, HIP85035

V636 Scorpii is a blue to white pulsating luminous giant star that can be located in the constellation of Scorpius. The star can not be seen by the naked eye, you need a telescope to see it.

HIP85035 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD156979.

V636 Scorpii has alternative name(s), V636 Sco.

Location of V636 Scorpii

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 V636 Scorpii, the location is 17h 22m 46.48 and -45 d 36`51.4 .

Proper Motion of V636 Scorpii

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 -2.40 ± 0.38 miliarcseconds/year towards the north and -3.05 ± 0.76 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of V636 Scorpii

V636 Scorpii has a spectral type of F7/F8Ib/II. This means the star is a blue to white luminous giant star. The star has a B-V Colour Index of 0.83 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,353 Kelvin. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

V636 Scorpii Apparent and Absolute Magnitudes

V636 Scorpii has an apparent magnitude of 6.68 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 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.02. 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 V636 Scorpii

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.00 which gave the calculated distance to V636 Scorpii as -1 light years away from Earth or -1 parsecs. It would take a spaceship travelling at the speed of light, -1 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 1.15 which put V636 Scorpii at a distance of 2836.20 light years or 869.57 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 V636 Scorpii

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. V636 Scorpii brightness ranges from a magnitude of 7.050 to a magnitude of 6.523 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 6.8 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.

V636 Scorpii Facts

Alternative Names

Traditional/Proper NameV636 Scorpii
Short NameV636 Sco
Hipparcos Library I.D.85035
Henry Draper Designation156979

Visual Facts

Star Typeluminous giant star
Visual / Apparent Magnitude6.68
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)17h 22m 46.48
Declination (Dec.)-45 d 36`51.4
Galactic Latitude-5.22 degrees
Galactic Longitude343.51 degrees
1997 Distance from Earth0.00 Parallax (milliarcseconds)
 -1 Light Years
 -1 Parsecs
2007 Revised Distance from Earth1.15 Parallax (milliarcseconds)
 2836.20 Light Years
 869.57 Parsecs
Proper Motion Dec.-2.40 ± 0.38 milliarcseconds/year
Proper Motion RA.-3.05 ± 0.76 milliarcseconds/year
B-V Index0.83
Radial Velocity9.09 ± 0.17 km/s
Spectral TypeF7/F8Ib/II
Colour(F) blue to white

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days6.797
Variable Magnitude Range (Brighter - Dimmer)6.523 - 7.050

Estimated Facts

Calculated Effective Temperature5,353 Kelvin

Sources and Links

SIMBAD SourceLink

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