BL Telescopii is a blue to white eclipsing very luminous supergiant star that can be located in the constellation of Telescopium. BL Telescopii is the brightest star in Telescopium based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.
HIP93844 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD177300.
BL Telescopii has alternative name(s), BL Tel.
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 BL Telescopii, the location is 19h 06m 38.11 and -51d25`03.2 .
BL Telescopii has a spectral type of F4Ib. This means the star is a blue to white supergiant star. The star has a B-V Colour Index of 0.52 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,064 Kelvin.
BL Telescopii Radius has been calculated as being 19.20 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 13,362,475.45.km. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.
BL Telescopii has an apparent magnitude of 7.19 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 -1.78 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 1.61 which gave the calculated distance to BL Telescopii as 2025.86 light years away from Earth or 621.12 parsecs. It would take a spaceship travelling at the speed of light, 2025.86 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a eclipsing Beta Persei (Algol)/System with one or both giant or supergiant components 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 Telescopii brightness ranges from a magnitude of 8.900 to a magnitude of 7.216 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 779.0 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.
|Traditional/Proper Name||BL Telescopii|
|Short Name||BL Tel|
|Hipparcos Library I.D.||93844|
|Henry Draper Designation||177300|
|Star Type||supergiant star|
|Visual / Apparent Magnitude||7.19|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||19h 06m 38.11|
|Galactic Latitude||-23.16 degrees|
|Galactic Longitude||345.53 degrees|
|1997 Distance from Earth||1.61 Parallax (milliarcseconds)|
|2025.86 Light Years|
|Radial Velocity||92.30 ± 2.90 km/s|
|Colour||(F) blue to white|
|Variable Star Class||Eclipsing|
|Variable Star Type||Beta Persei (Algol)/System with one or both giant or supergiant components|
|Mean Variability Period in Days||779.000|
|Variable Magnitude Range (Brighter - Dimmer)||7.216 - 8.900|
|Calculated Effective Temperature||6,064 Kelvin|