HIP18165 is the reference name for the star in the Hipparcos Star Catalogue.
BL Tauri has alternative name(s) :- , BL Tau.
BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+19 607.
More details on objects' alternative names can be found at Star Names .
The location of the variable star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For BL Tauri, the location is 03h 53m 01.63 and +20° 12` 28.9 .
BL Tauri has a spectral type of M4.5. This means the star is a red variable star. The star has a B-V Colour Index of 1.47 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,076 Kelvin.
BL Tauri Radius has been calculated as being 9.47 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,590,296.43.km. If you need the diameter of the star, you just need to multiple the radius by 2. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.
BL Tauri has an apparent magnitude of 8.97 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 1.48 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.17 which gave the calculated distance to BL Tauri as 1028.91 light years away from Earth or 315.46 parsecs. It would take a spaceship travelling at the speed of light, 1028.91 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a pulsating Semi-Regular Star w 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. BL Tauri brightness ranges from a magnitude of 8.738 to a magnitude of 8.409 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 days (variability).
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.
|Primary / Proper / Traditional Name||BL Tauri|
|Alternative Names||HIP 18165, BD+19 607, BL Tau|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Variable Star|
|Visual / Apparent Magnitude||8.97|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||03h 53m 01.63|
|Declination (Dec.)||+20° 12` 28.9|
|Galactic Latitude||-25.40 degrees|
|Galactic Longitude||170.64 degrees|
|Distance from Earth||3.17 Parallax (milliarcseconds)|
|1028.91 Light Years|
|65,067,842.38 Astronomical Units|
|Radial Velocity||-80.00 ± 7.40 km/s|
|Variable Star Class||Pulsating|
|Variable Star Type||Semi-Regular Star w|
|Mean Variability Period in Days||0.293|
|Variable Magnitude Range (Brighter - Dimmer)||8.409 - 8.738|
|Radius (x the Sun)||9.47|
|Effective Temperature||4,076 Kelvin|
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