SIRIUS
DISTANCE: 8.6 ly (light years from earth)
APPARENT MAGNITUDE*: −26.74 m
SPECTRAL CLASS**: A1 V
*apparent magnitude is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere. The brighter the object appears, the lower the value of its magnitude.
**the spectral class is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure of the temperature in this chromosphere. (http://outreach.atnf.csiro.au/education/senior/astrophysics/spectral_class.html)
At 8.6 light-years distance, Sirius is one of the nearest stars to us after the sun. (A light year is nearly 6 trillion miles!) In fact it is the nearest star easily visible to the unaided eye from most of the northern hemisphere. Classified by astronomers as an “A” type star, it is much hotter than our sun, with about surface about 17,000 degrees F (the sun is about 10,000 degrees F). With slightly more than twice the mass of the sun and just less than twice its diameter, Sirius still puts out 26 times as much energy. It is considered a normal (main sequence) star, meaning that it produces most of its energy by converting hydrogen into helium through nuclear fusion. As mentioned above, Sirius has a small, faint companion star appropriately called “The Pup.” That name signifies youth, but in fact “The Pup” is a dead star called a “white dwarf.” Once a mighty star, today it is an earth-sized ember too faint to be seen without a telescope.
DISTANCE: 8.6 ly (light years from earth)
APPARENT MAGNITUDE*: −26.74 m
SPECTRAL CLASS**: A1 V
*apparent magnitude is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere. The brighter the object appears, the lower the value of its magnitude.
**the spectral class is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure of the temperature in this chromosphere. (http://outreach.atnf.csiro.au/education/senior/astrophysics/spectral_class.html)
At 8.6 light-years distance, Sirius is one of the nearest stars to us after the sun. (A light year is nearly 6 trillion miles!) In fact it is the nearest star easily visible to the unaided eye from most of the northern hemisphere. Classified by astronomers as an “A” type star, it is much hotter than our sun, with about surface about 17,000 degrees F (the sun is about 10,000 degrees F). With slightly more than twice the mass of the sun and just less than twice its diameter, Sirius still puts out 26 times as much energy. It is considered a normal (main sequence) star, meaning that it produces most of its energy by converting hydrogen into helium through nuclear fusion. As mentioned above, Sirius has a small, faint companion star appropriately called “The Pup.” That name signifies youth, but in fact “The Pup” is a dead star called a “white dwarf.” Once a mighty star, today it is an earth-sized ember too faint to be seen without a telescope.
