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RU Scuti, HD172730, HIP91697

RU Scuti is a blue to white pulsating star that can be located in the constellation of Scutum. RU Scuti is the brightest star in Scutum based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP91697 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD172730.

RU Scuti has alternative name(s), RU Sct.

Location of RU Scuti

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 RU Scuti, the location is 18h 41m 56.38 and -04d 06` 38.4 .

Proper Motion of RU Scuti

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 -2.65 ± 1.20 miliarcseconds/year towards the north and 0.99 ± 2.30 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of RU Scuti

RU Scuti has a spectral type of F9.5. This means the star is a blue to white star. The star has a B-V Colour Index of 1.81 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 2,975 Kelvin.

RU Scuti Radius has been calculated as being 51.04 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 35,515,819.68.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 11.17. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

RU Scuti Apparent and Absolute Magnitudes

RU Scuti has an apparent magnitude of 9.44 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 -0.81 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.49. 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 RU Scuti

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.89 which gave the calculated distance to RU Scuti as 3664.76 light years away from Earth or 1123.60 parsecs. It would take a spaceship travelling at the speed of light, 3664.76 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 4.07 which put RU Scuti at a distance of 801.38 light years or 245.70 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 RU Scuti

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. RU Scuti brightness ranges from a magnitude of 9.993 to a magnitude of 8.983 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 19.7 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.

RU Scuti Facts

Alternative Names

Traditional/Proper NameRU Scuti
Short NameRU Sct
Hipparcos Library I.D.91697
Bonner DurchmusterungBD-04 4553
Henry Draper Designation172730

Visual Facts

Star Type star
Absolute Magnitude-0.81 / 2.49
Visual / Apparent Magnitude9.44
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)18h 41m 56.38
Declination (Dec.)-04d 06` 38.4
Galactic Latitude0.23 degrees
Galactic Longitude28.19 degrees
1997 Distance from Earth0.89 Parallax (milliarcseconds)
 3664.76 Light Years
 1123.60 Parsecs
2007 Revised Distance from Earth4.07 Parallax (milliarcseconds)
 801.38 Light Years
 245.70 Parsecs
Proper Motion Dec.-2.65 ± 1.20 milliarcseconds/year
Proper Motion RA.0.99 ± 2.30 milliarcseconds/year
B-V Index1.81
Radial Velocity-4.80 ± 0.30 km/s
Spectral TypeF9.5
Colour(F) blue to white

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days19.699
Variable Magnitude Range (Brighter - Dimmer)8.983 - 9.993

Estimated Facts

Calculated Effective Temperature2,975 Kelvin

Sources and Links

SIMBAD SourceLink

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