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Updated February 01, 2013

List of brightest stars

More than 200 billion stars

The space is huge, our Milky Way galaxy contains over 200 billion stars distributed in a volume of 100 000 light-years in diameter. But to the naked eye, we see in the night sky that 9000 stars on a clear night, away from cities and flare the earth's surface.
The brightest stars are ranked by their average apparent magnitudes in the spectrum of visible light, seen from Earth.
Visible light is only a small range of electromagnetic vibrations found in the electromagnetic spectrum.
The light has a wavelength, which determines the color, for example red emitting in the wavelength of 700 nanometers, Orange 650 nm, Yellow 600 nm, Green 550 nm, Blue 500 nm and Violet 450 nm. It is this window that chose the human eye to specialize. But the invisible light is spread over a larger electromagnetic field.
The apparent magnitude does not indicate the intrinsic brightness of the star, in contrast to the absolute magnitude The absolute magnitude indicates the actual brightness of a celestial object, while the apparent magnitude depends on the distance of the object. The absolute magnitude of a star is defined as the apparent magnitude the star would have a distance of reference of 10 parsecs (≈32.6 light years) and in the absence of interstellar extinction (dustless between the object and the observer). A gain with a magnitude, corresponds to 2.5 times less brilliance. Example: the magnitude 1 of an object, is 2.5 times less bright than magnitude 2. . The apparent magnitude The brightness measured from Earth of a star or other celestial object is expressed in apparent magnitude. The magnitude scale is logarithmic and reversed, that is to say, the lowest magnitudes correspond to the brightest objects. A gain with a magnitude, corresponds to 2.5 times less brilliance. Example: the magnitude 1 of an object, is 2.5 times less bright than magnitude 2.  of course depends on the intrinsic brightness of the star but especially the distance from the Earth because the closest stars appear brighter.
Most stars are part of a binary or multiple system. Seen from Earth, they appear as a single star with an apparent magnitude greater than their individual brilliance.
The binary system of Rigel Kentaurus componed the star α Centauri A and star α Centauri B, the apparent magnitude of the couple is -0.27 while the apparent magnitude of α Centauri A is +0.01 and apparent magnitude of α Centauri B is +1.34, the couple is more brilliant, that's why it is ranked third after the Sun, in the table against.
Sirius is the brightest star in the night sky, but Sirius is a binary system, with the naked eye, we see only a single white star.
Sirius A is actually a white star, aged about 250 million years, with a mass of 2.1 solar masses, its surface temperature of about 9900 K and its diameter about 1.7 times the solar diameter. its companion, Sirius B is a white dwarf, i.e. a residue of star extinguished. This is the penultimate stage of the evolution of stars whose mass is between 0.3 and 1.4 times that of the sun. Sirius B orbits the center of mass of the pair, with a period of nearly 50 years. The distance between the two stars varies between 8.1 and 31.5 astronomical units (average distance 19.5 AU).

nota : Canicule comes from the word Canicula (little dog), the star Sirius in Latin. Sirius A is main star of Canis (Canis Major) also known as the "Dog of Orion". Sirius, whose name means "brilliant" is the brightest star in the sky because of its proximity to the Earth (8.6 AL). By metonymy and antonomasia, this name has passed into the language as a common name for the period of high heat during which Sirius rises and sets precisely with the Sun (July 24 to August 24). By extension, the word canicule was applied to any period of extreme heat, and gave as derived from the canicular adjective. Excessively sunny weather. Dryness of exceptional amplitude becomes natural disaster.

Star
Designation
Stellar
Class
magnitude
apparent
Distance
(ly)
       
Sun G2 V -26.74 0
Sirius A1 V -1.46 8.58
Canopus F0 Ib -0.72 310
α Centauri AB G2 V -0.27 4.39
Arcturus K0 III -0.04 37
Vega A0 Va 0.03 25
Capella K0 III 0.08 42
Rigel B8 Ia 0.12 860
Procyon F5 IV-V 0.34 11.50
Betelgeuse M2 Iab 0.42 640
Achemar B6 Vep 0.50 140
Hadar (Agena) B1 III 0.60 140
Altair A7 V 0.77 17
Acrux B8 Ia 0.77 320
Aldebaran K5 III 0.85 65
Spica B1 III-IV 1.04 260
Antares M1.5 Iab 1.09 600
Pollux K0 III 1.15 34
Fomalhaut A3 V 1.16 25
Deneb A2 Ia 1.25 2600
Mimosa B0.5 II 1.30 350
Regulus B7 V 1.35 77
Adara B2 Iab 1.51 430
Castor A1 V 1.58 52
Shaula B2 IV 1.62 700
Gacrux M3.5 III 1.63 88
Bellatrix B2 III 1.64 240
El Nath B7 III 1.68 130
Miaplacidus A1 III 1.68 110
Alnilam B0 Ia 1.70 1300
Alnitak O9.7 Ib 1.70 820
Alnair B7 IV 1.74 100
Alioth A1 III 1.76 81
Gamma Velorum WC8 1.78 840
Dubhe G9 III 1.79 120
Kaus Australis B9.5 III 1.80 140
Mirfak F5 Ib 1.82 590
Wezen F8 Ia 1.84 1800
Nenetnasch B3 V 1.85 100
Sargas F0 II 1.86 270
Avior K3 III 1.86 630
Alhena A1.5 IV 1.90 100
Peacock B2 IV 1.91 180

Table: list of the brightest stars in the order of their average apparent magnitude. For comparison, here are the maximum apparent magnitudes of the objects in our solar system: Moon (-12.92), Venus (-4.89), Jupiter (-2.94), Mars (-2.91), Mercury (-2.45) and Saturn (-0.49). To understand the colors of stars. see stars categories.

Sirius, brightest star

Image: Alpha Canis Majoris. The brightest star in the night sky after the Sun, is the white star Sirius (α CMa) located only 8.5 light-years away in the constellation Canis Major with Wezen and Adhara, other stars among the brightest.


 pc Le parsec est la distance à laquelle une unité astronomique (UA) sous-tend un angle d'une seconde d'arc.al Une année-lumière est égale à la distance que parcourt la lumière dans le vide pendant une année, soit exactement égale à 9 460 895 288 762 850 mètres. Une année-lumière vaut approximativement 63 241 ua.ua Créée en 1958, c’est l'unité de distance utilisée pour mesurer les distances des objets du système solaire, cette distance est égale à la distance de la Terre au Soleil. La valeur de l'unité astronomique représente exactement 149 597 870 700 m, lors de son assemblée générale tenue à Pékin, du 20 au 31 août 2012, l'Union astronomique internationale (UAI) a adopté une nouvelle définition de l'unité astronomique, unité de longueur utilisée par les astronomes du monde entier pour exprimer les dimensions du Système solaire. On retiendra environ 150 millions de kilomètres. Mercure : 0,38 ua, Vénus : 0,72 ua, Terre : 1,00 ua, Mars : 1,52 ua, Ceinture d’astéroïdes : 2 à 3,5 ua, Jupiter : 5,21 ua, Saturne : 9,54 ua, Uranus : 19,18 ua, Neptune : 30,11 ua, Ceinture de Kuiper : 30 à 55 ua, Nuage d’Oort : 50000 ua.km Le kilomètre (symbole km) est une unité de mesure de longueur, multiple du mètre. 1 km = 1 000 m. Le kilomètre est utilisé pour mesurer les distances à l'échelle de l'homme, celle de la Terre.
pc Le parsec est la distance à laquelle une unité astronomique (UA) sous-tend un angle d'une seconde d'arc.13,262062653,09x1013
al Une année-lumière est égale à la distance que parcourt la lumière dans le vide pendant une année, soit exactement égale à 9 460 895 288 762 850 mètres. Une année-lumière vaut approximativement 63 241 ua.0,3071632419,46x1012
ua (symbol : ua ou au) Créée en 1958, c’est l'unité de distance utilisée pour mesurer les distances des objets du système solaire, cette distance est égale à la distance de la Terre au Soleil. La valeur de l'unité astronomique représente exactement 149 597 870 700 m, lors de son assemblée générale tenue à Pékin, du 20 au 31 août 2012, l'Union astronomique internationale (UAI) a adopté une nouvelle définition de l'unité astronomique, unité de longueur utilisée par les astronomes du monde entier pour exprimer les dimensions du Système solaire et de l’Univers. On retiendra environ 150 millions de kilomètres. Mercure : 0,38 ua, Vénus : 0,72 ua, Terre : 1,00 ua, Mars : 1,52 ua, Ceinture d’astéroïdes : 2 à 3,5 ua, Jupiter : 5,21 ua, Saturne : 9,54 ua, Uranus : 19,18 ua, Neptune : 30,11 ua, Ceinture de Kuiper : 30 à 55 ua, Nuage d’Oort : 50 000 ua.4,85x10-61,58x10-511,50x108
km Le kilomètre (symbole km) est une unité de mesure de longueur, multiple du mètre. 1 km = 1 000 m. Le kilomètre est utilisé pour mesurer les distances à l'échelle de l'homme, celle de la Terre. 3,24x10-141,06x10-136,68x10-91

Table: equivalences between the distance units (parsec, light year, astronomical unit and km).

What is a light year?
A light year is ≈10 000 billion km. This distance seems very high but the Oort cloud This remote and invisible region of the Solar System is located at 7500 billion km. It hosts billions of light icy body, to the limit of the attraction of the Sun can be disturbed by the slightest gravitational force, of the nearest stars of the solar system., a region of the solar system, is located at ≈7500 billion km and contains billions of icy bodies at the edge of the attraction of the Sun.

nota : white stars are stars of the main sequence of spectral type A and luminosity class V. In contrast to white dwarfs, which are low-mass stars residues, white stars are stars whose surface temperature varies between 7 100 K and 9 750 K and mass between 1.5 and 3 solar masses. Their spectrum has intense hydrogen lines because their energy comes from the fusion of their hydrogen into helium. These are usually young stars of a few hundred million years.
Sirius A is a white star, aged about 250 million years, with a mass of 2.1 solar masses, its surface temperature of approximately 9 900 K and its diameter about 1.7 times the diameter solar. Its companion, Sirius B is a white dwarf.
White stars: Sirius (α Canis Majoris), Vega (α Lyr)

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