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Stars that have magnitudes between 1.5 and 2.5 are called second-magnitude; there are some 20 stars brighter than 1.5, which are first-magnitude stars (see the list of brightest stars). For example, Sirius is magnitude −1.46, Arcturus is −0.04, Aldebaran is 0.85, Spica is 1.04, and Procyon is 0.34. Under the ancient magnitude system, all of ...
0.96–1.15 R ☉ 0.6–1.5 ... letter S and a number between zero and ten. ... years the temperature of an isolated neutron star falls from the order of billions to ...
−0.04: star Arcturus: seen from Earth 4th brightest star to the naked eye [47] −0.01: star Alpha Centauri A: seen from Earth 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 ...
A difference of 5 magnitudes between the absolute magnitudes of two objects corresponds to a ratio of 100 in their luminosities, and a difference of n magnitudes in absolute magnitude corresponds to a luminosity ratio of 100 n/5. For example, a star of absolute magnitude M V = 3.0 would be 100 times as luminous as a star of absolute magnitude M ...
A class of extrasolar planets whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close—between approximately 0.015 and 0.5 AU (2.2 × 10 ^ 6 and 74.8 × 10 ^ 6 km)—to their parent stars, whereas Jupiter orbits its parent star (the Sun) at 5.2 AU (780 × 10 ^ 6 km), causing low ...
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
An artist's impression of Sirius A and Sirius B, a binary star system. Sirius A, an A-type main-sequence star, is the larger of the two. An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer ...
The Hubble Space Telescope's Wide Field Camera 3 has the potential to provide a precision of 20 to 40 microarcseconds, enabling reliable distance measurements up to 5,000 parsecs (16,000 ly) for small numbers of stars. [5] [6] The Gaia space mission provided similarly accurate distances to most stars brighter than 15th magnitude. [7]