Universe Guide


25 Sextantis - HD90044 - HIP50885

25 Sextantis is a blue rotating star that can be located in the constellation of Sextans. HIP50885 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD90044. 25 Sextantis has alternative name(s), 25 Sextantis , SS_Sex, 25 Sex.

Location of 25 Sextantis

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 25 Sextantis, the location is 10h 23m 26.51 and -04d04`26.6 .

Proper Motion of 25 Sextantis

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 003.93 ± 000.44 towards the north and -049.42 ± 000.73 east if we saw them in the horizon.

25 Sextantis Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 61000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of 25 Sextantis

25 Sextantis has a spectral type of B9p Si(CrSr). This means the star is a blue star. The star has a B-V Colour Index of -0.04 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,437 Kelvin.

25 Sextantis has been calculated as 1.67 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,160,796.34.km.

25 Sextantis Apparent and Absolute Magnitudes

25 Sextantis has an apparent magnitude of 5.93 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 0.77 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.84. 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 25 Sextantis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.28 which gave the calculated distance to 25 Sextantis as 351.47 light years away from Earth or 107.76 parsecs. It would take a spaceship travelling at the speed of light, 351.47 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 9.60 which put 25 Sextantis at a distance of 339.75 light years or 104.17 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 25 Sextantis

The star is a rotating Alpha2 Canum Venaticorum 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. 25 Sextantis brightness ranges from a magnitude of 6.000 to a magnitude of 6.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 4.0 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

25 Sextantis Facts

Alternative Names

Traditional Name25 Sextantis
Short NameSS Sex, 25 Sex
Alternative Name(s)25 Sextantis
Hipparcos Library I.D.50885
Bonner DurchmusterungBD-03 2911
Henry Draper Designation90044

Visual Facts

Star Type star
Absolute Magnitude0.77 / 0.84
Apparent Magnitude5.93
Right Ascension (R.A.)10h 23m 26.51
Declination (Dec.)-04d04`26.6
1997 Distance from Earth9.28 Parallax (milliarcseconds)
 351.47 Light Years
 107.76 Parsecs
2007 Revised Distance from Earth9.60 Parallax (milliarcseconds)
 339.75 Light Years
 104.17 Parsecs
Proper Motion Dec.3.93 ± 0.44 milliarcseconds/year
Proper Motion RA.-49.42 ± 0.73 milliarcseconds/year
B-V Index-0.04
Spectral TypeB9p Si(CrSr)
Colour(B) blue

Variable Star Details

Variable Star ClassRotating
Variable Star TypeAlpha2 Canum Venaticorum
Mean Variability Period in Days4.000

Estimated Facts

Radius (x the Sun)1.67
Luminosity (x the Sun)61,000.0000000
Calculated Effective Temperature11,437 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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