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T Tauri, HD284419, HIP20390

T Tauri is a orange to red eruptive star that can be located in the constellation of Taurus. The star can not be seen by the naked eye, you need a telescope to see it.

HIP20390 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD284419.

T Tauri has alternative name(s), T Tau.

Location of T 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 T Tauri, the location is 04h 21m 59.42 and +19d 32` 06.5 .

Proper Motion of T 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 -13.67 ± 1.03 miliarcseconds/year towards the north and 15.51 ± 1.58 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 23.90000 km/s with an error of about 1.50 km/s .

T Tauri 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 96.0000000 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 T Tauri

T Tauri has a spectral type of K0IIIe. This means the star is a orange to red star. The star has a B-V Colour Index of 1.11 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,646 Kelvin.

T Tauri Radius has been calculated as being 2.78 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,937,288.81.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.88. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

T Tauri Apparent and Absolute Magnitudes

T Tauri has an apparent magnitude of 9.81 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 3.57 If you used the 2007 Parallax value, you would get an absolute magnitude of 3.50. 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 T Tauri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.66 which gave the calculated distance to T Tauri as 576.26 light years away from Earth or 176.68 parsecs. It would take a spaceship travelling at the speed of light, 576.26 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 5.48 which put T Tauri at a distance of 595.19 light years or 182.48 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 T Tauri

The star is a eruptive Irregular 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. T Tauri brightness ranges from a magnitude of 10.124 to a magnitude of 9.870 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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.

T Tauri Facts

Alternative Names

Traditional/Proper NameT Tauri
Short NameT Tau
Hipparcos Library I.D.20390
Bonner DurchmusterungBD+19 706
Henry Draper Designation284419

Visual Facts

Star Type star
Absolute Magnitude3.57 / 3.50
Visual / Apparent Magnitude9.81
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)04h 21m 59.42
Declination (Dec.)+19d 32` 06.5
Galactic Latitude-20.89 degrees
Galactic Longitude176.23 degrees
1997 Distance from Earth5.66 Parallax (milliarcseconds)
 576.26 Light Years
 176.68 Parsecs
2007 Revised Distance from Earth5.48 Parallax (milliarcseconds)
 595.19 Light Years
 182.48 Parsecs
Proper Motion Dec.-13.67 ± 1.03 milliarcseconds/year
Proper Motion RA.15.51 ± 1.58 milliarcseconds/year
B-V Index1.11
Radial Velocity23.90 ± 1.50 km/s
Spectral TypeK0IIIe
Colour(K) Orange to Red

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeIrregular
Mean Variability Period in Days0.177
Variable Magnitude Range (Brighter - Dimmer)9.870 - 10.124

Estimated Facts

Luminosity (x the Sun)96.0000000
Calculated Effective Temperature4,646 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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