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Sigma1 Tauri - HD29479 - HIP21673

Sigma1 Tauri is a blue star that can be located in the constellation of Taurus. Sigma1 Tauri is the Bayer Classification for the star. HIP21673 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD29479. Sigma1 Tauri has alternative name(s), 91 Tauri , 91 Tau.

Location of Sigma1 Tauri

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 Sigma1 Tauri, the location is 04h 39m 09.20 and +15d48`00.1 .

Proper Motion of Sigma1 Tauri

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 -066.88 ± 000.62 towards the north and 041.91 ± 000.93 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Sigma1 Tauri

Sigma1 Tauri has a spectral type of A4m. This means the star is a blue star. The star has a B-V Colour Index of 0.14 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,950 Kelvin.

Sigma1 Tauri has been calculated as 2.21 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,536,867.73.km.

Sigma1 Tauri Apparent and Absolute Magnitudes

Sigma1 Tauri has an apparent magnitude of 5.08 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 1.74 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.81. 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 Sigma1 Tauri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 21.49 which gave the calculated distance to Sigma1 Tauri as 151.77 light years away from Earth or 46.53 parsecs. It would take a spaceship travelling at the speed of light, 151.77 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 22.18 which put Sigma1 Tauri at a distance of 147.05 light years or 45.09 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.

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.

Sigma1 Tauri Facts

Alternative Names

Short Name91 Tau
Bayer DesignationSigma1 Tauri
Alternative Name(s)91 Tauri
Hipparcos Library I.D.21673
Bonner DurchmusterungBD+15 665
Henry Draper Designation29479

Visual Facts

Star Type star
Absolute Magnitude1.74 / 1.81
Apparent Magnitude5.08
Right Ascension (R.A.)04h 39m 09.20
Declination (Dec.)+15d48`00.1
1997 Distance from Earth21.49 Parallax (milliarcseconds)
 151.77 Light Years
 46.53 Parsecs
2007 Revised Distance from Earth22.18 Parallax (milliarcseconds)
 147.05 Light Years
 45.09 Parsecs
Proper Motion Dec.-66.88 ± 0.62 milliarcseconds/year
Proper Motion RA.41.91 ± 0.93 milliarcseconds/year
B-V Index0.14
Spectral TypeA4m
Colour(A) blue

Estimated Facts

Radius (x the Sun)2.21
Calculated Effective Temperature7,950 Kelvin

Sources and Links

SIMBAD SourceLink

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