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A star like Deneb, for example, has a luminosity around 200,000 L ⊙, a spectral type of A2, and an effective temperature around 8,500 K, meaning it has a radius around 203 R ☉ (1.41 × 10 11 m). For comparison, the red supergiant Betelgeuse has a luminosity around 100,000 L ⊙ , a spectral type of M2, and a temperature around 3,500 K ...
In astronomy, absolute magnitude (M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale; the more luminous (intrinsically bright) an object, the lower its magnitude number.
A more complex definition of absolute magnitude is used for planets and small Solar System bodies, based on its brightness at one astronomical unit from the observer and the Sun. The Sun has an apparent magnitude of −27 and Sirius, the brightest visible star in the night sky, −1.46. Venus at its brightest is -5.
Photometric measurements can be combined with the inverse-square law to determine the luminosity of an object if its distance can be determined, or its distance if its luminosity is known. Other physical properties of an object, such as its temperature or chemical composition, may also be determined via broad or narrow-band spectrophotometry.
The Paranal Observatory of European Southern Observatory shooting a laser guide star to the Galactic Center. Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution.
4th brightest individual star visible telescopically in the night sky +0.03: star Vega: seen from Earth originally chosen as a definition of the zero point [48] +0.23: planet Mercury: seen from Earth mean brightness [42] +0.46: star Sun: seen from Alpha Centauri +0.46: planet Saturn: seen from Earth mean brightness [42] +0.71: planet Mars: seen ...
Stellar structure models describe the internal structure of a star in detail and make predictions about the luminosity, the color and the future evolution of the star. Different classes and ages of stars have different internal structures, reflecting their elemental makeup and energy transport mechanisms.
In SI units, luminosity is measured in joules per second or watts, and is often given in terms of astronomical magnitude. Luminosity is related to but distinct from visual brightness. lunar Of or relating to the Earth's Moon. lunar phase. Also Moon phase. The shape of the portion of the Moon that is illuminated by direct sunlight as viewed from ...