Universe Guide


Psi Tauri - HD25867 - HIP19205

Psi Tauri is a blue to white main sequence dwarf star that can be located in the constellation of Taurus. Psi Tauri is the Bayer Classification for the star. HIP19205 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD25867. Psi Tauri has alternative name(s), 42 Tauri , 42 Tau.

Location of Psi 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 Psi Tauri, the location is 04h 07m 00.52 and +29d00`04.6 .

Proper Motion of Psi 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 007.58 ± 000.25 towards the north and -091.40 ± 000.35 east if we saw them in the horizon.

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

Psi Tauri has a spectral type of F1V. This means the star is a blue to white main sequence dwarf star. The star has a B-V Colour Index of 0.35 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,967 Kelvin.

Psi Tauri has been calculated as 1.60 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,114,978.92.km.

Psi Tauri Apparent and Absolute Magnitudes

Psi Tauri has an apparent magnitude of 5.21 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 3.01 If you used the 2007 Parallax value, you would get an absolute magnitude of 3.01. 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 Psi Tauri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 36.26 which gave the calculated distance to Psi Tauri as 89.95 light years away from Earth or 27.58 parsecs. It would take a spaceship travelling at the speed of light, 89.95 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 36.23 which put Psi Tauri at a distance of 90.03 light years or 27.60 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.

Psi Tauri Facts

Alternative Names

Short Name42 Tau
Bayer DesignationPsi Tauri
Alternative Name(s)42 Tauri
Hipparcos Library I.D.19205
Bonner DurchmusterungBD+28 619
Henry Draper Designation25867

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude3.01 / 3.01
Apparent Magnitude5.21
Right Ascension (R.A.)04h 07m 00.52
Declination (Dec.)+29d00`04.6
1997 Distance from Earth36.26 Parallax (milliarcseconds)
 89.95 Light Years
 27.58 Parsecs
2007 Revised Distance from Earth36.23 Parallax (milliarcseconds)
 90.03 Light Years
 27.60 Parsecs
Proper Motion Dec.7.58 ± 0.25 milliarcseconds/year
Proper Motion RA.-91.40 ± 0.35 milliarcseconds/year
B-V Index0.35
Spectral TypeF1V
Colour(F) blue to white

Estimated Facts

Radius (x the Sun)1.60
Calculated Effective Temperature6,967 Kelvin

Sources and Links

SIMBAD SourceLink

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