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  2. Apparent magnitude - Wikipedia

    en.wikipedia.org/wiki/Apparent_magnitude

    Flux decreases with distance according to an inverse-square law, so the apparent magnitude of a star depends on both its absolute brightness and its distance (and any extinction). For example, a star at one distance will have the same apparent magnitude as a star four times as bright at twice that distance.

  3. Magnitude (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Magnitude_(astronomy)

    Early photometric measurements (made, for example, by using a light to project an artificial “star” into a telescope's field of view and adjusting it to match real stars in brightness) demonstrated that first magnitude stars are about 100 times brighter than sixth magnitude stars.

  4. Absolute magnitude - Wikipedia

    en.wikipedia.org/wiki/Absolute_magnitude

    The Greek astronomer Hipparchus established a numerical scale to describe the brightness of each star appearing in the sky. The brightest stars in the sky were assigned an apparent magnitude m = 1, and the dimmest stars visible to the naked eye are assigned m = 6. [7] The difference between them corresponds to a factor of 100 in brightness.

  5. Phase curve (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Phase_curve_(astronomy)

    In astronomy, a phase curve describes the brightness of a reflecting body as a function of its phase angle (the arc subtended by the observer and the Sun as measured at the body). The brightness usually refers the object's absolute magnitude, which, in turn, is its apparent magnitude at a distance of one astronomical unit from the Earth and Sun.

  6. Luminosity - Wikipedia

    en.wikipedia.org/wiki/Luminosity

    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 ...

  7. Luminosity distance - Wikipedia

    en.wikipedia.org/wiki/Luminosity_distance

    Luminosity distance D L is defined in terms of the relationship between the absolute magnitude M and apparent magnitude m of an astronomical object. = ⁡ which gives: = + where D L is measured in parsecs.

  8. Brightness - Wikipedia

    en.wikipedia.org/wiki/Brightness

    As defined by the US Federal Glossary of Telecommunication Terms , "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light. [3] Brightness is an antonym of "dimness" or "dullness". With regard to stars, brightness is quantified as apparent magnitude and absolute magnitude.

  9. Visual binary - Wikipedia

    en.wikipedia.org/wiki/Visual_binary

    The greater a star's luminosity, the greater its mass will be. The absolute magnitude or luminosity of a star can be found by knowing the distance to it and its apparent magnitude. The stars bolometric magnitude is plotted against its mass, in units of the Sun's mass. This is determined through observation and then the mass of the star is read ...