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71 Orionis
This is the list of notable stars in the constellation Orion, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spl ... References * * * * * {{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System *List Orion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night, but their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Brightest Stars
This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. Stars in binary systems (or other multiples) are listed by their ''total'' or ''combined'' brightness if they appear as a single star to the naked eye, or listed separately if they do not. As with all magnitude systems in astronomy, the scale is logarithmic and inverted i.e. lower/more negative numbers are brighter. Most stars on this list appear bright from Earth because they are nearby, not because they are intrinsically luminous. For a list which compensates for the distances, converting the ''apparent'' magnitude to the ''absolute'' magnitude, see the list of most luminous stars. Measurement The Sun is the brightest star as viewed from Earth, at −26.74 mag. The second brightest is Sirius at −1.46 mag. For c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Orionis
Iota Orionis (ι Orionis, abbreviated ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly from the Sun. The system has three visible components designated Iota Orionis A, B and C. Iota Orionis A has also been resolved using speckle interferometry and is also a massive spectroscopic binary, with components Iota Orionis Aa1 (officially named Hatysa ), Aa2, and Ab. Nomenclature ''ι Orionis'' ( Latinised to ''Iota Orionis'') is the system's Bayer designation. The designations of the three constituents as ''Iota Orionis A'', ''B'' and ''C'', and those of ''A's'' components - ''Iota Orionis Aa1'', ''Aa2'', and ''Ab'' - derive from the convention used by the Washing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algol Variable
Algol variables or Algol-type binaries are a class of eclipsing binary stars that are similar to the prototype member of this class, β Persei (Beta Persei, Algol). An Algol binary is a system where both stars are near-spherical such that the timing of the start and end of the eclipses is well-defined. The primary is generally a main sequence star well within its Roche lobe. The secondary may also be a main sequence star, referred to as a detached binary or it may an evolved star filling its Roche lobe, referred to as a semidetached binary. When the cooler component passes in front of the hotter one, part of the latter's light is blocked, and the total brightness of the binary, as viewed from Earth, temporarily decreases. This is the primary minimum of the binary. Total brightness may also decrease, but less so, when the hotter component passes in front of the cooler one; this is the secondary minimum. The period, or time span between two primary minima, is very regular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mintaka
Mintaka , designation Delta Orionis (δ Orionis, abbreviated Delta Ori, δ Ori) and 34 Orionis (34 Ori), is a multiple star system some 1,200 light-years from the Sun in the constellation of Orion. Together with Alnitak (Zeta Orionis) and Alnilam (Epsilon Orionis), the three stars form Orion's Belt, known by many names among ancient cultures. The star is located very close to the celestial equator. When Orion is near the meridian, Mintaka is the rightmost of the Belt's stars when viewed from the Northern Hemisphere facing south. Nomenclature ''Delta Orionis'' is the star's Bayer designation, ''34 Orionis'' its Flamsteed designation. The name ''Mintaka'' itself is derived from an Arabic term for 'belt': منطقة or ''manṭaqa''. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saiph
Saiph , designation Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the star at the south-eastern corner. A northern-hemisphere observer facing south would see it at the lower left of Orion, and a southern-hemisphere observer facing north would see it at the upper right. Parallax measurements yield an estimated distance of from the Sun, which is about the same as Betelgeuse. It is smaller, less luminous but hotter at its surface than Rigel with an apparent visual magnitude of 2.1. The luminosity of this star changes slightly, varying by 0.04 magnitudes. Nomenclature ''Kappa Orionis'' is the star's Bayer designation and ''53 Orionis'' its Flamsteed designation. The traditional name ''Saiph'' is from the Arabic ''saif al jabbar'', 'سیف الجبّار' literally '' saif of the giant''. This name was originally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alnitak
Alnitak is a triple star system in the constellation of Orion. It has the designations ζ Orionis, which is Latinised to Zeta Orionis and abbreviated Zeta Ori or ζ Ori, and 50 Orionis, abbreviated 50 Ori. The system is located at a distance of several hundred parsecs from the Sun and is one of the three main stars of Orion's Belt along with Alnilam and Mintaka. The primary star, Alnitak Aa, is a hot blue supergiant with an absolute magnitude of −6.0 and is the brightest class O star in the night sky with a visual magnitude of +2.0. It has two companions—Ab and B, the latter known for the longest time and the former discovered recently, producing a combined magnitude for the trio of +1.77. The stars are members of the Orion OB1 association and the association. Observational history Alnitak has been known since antiquity and, as a component of Orion's Belt, has been of widespread cultural significance. It was reported to be a double star by amateur German astr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alnilam
Alnilam is the central star of Orion's Belt in the equatorial constellation of Orion. It has the Bayer designation ε Orionis, which is Latinised to Epsilon Orionis and abbreviated Epsilon Ori or ε Ori. This is a massive, blue supergiant star some 2,000 light-years distant. It is estimated to be 275,000 to 832,000 times as luminous as the Sun, and 40 to 44 times as massive. Observation It is the 29th-brightest star in the sky (the fourth brightest in Orion) and is a blue supergiant. Together with Mintaka and Alnitak, the three stars make up Orion's Belt, known by many names across many ancient cultures. Alnilam is the middle star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified, for the spectral class B0Ia. Although the spectrum shows variations, particular in the H-alpha absorption lines, this is considered typical for this type of luminous hot supergiant. It is also one of the 58 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellatrix
Bellatrix is the third-brightest star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse (Alpha Orionis). It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly variable magnitude of around 1.6, it is typically the 25th-brightest star in the night sky. Located at a distance of 250 light-years from the Sun, it is a blue giant star around 7.7 times as massive as the sun with 5.75 times its diameter. Nomenclature The traditional name ''Bellatrix'' is from the Latin ''bellātrix'' "female warrior"; it first appeared in the works of Abu Ma'shar al-Balkhi and Johannes Hispalensis, where it originally referred to Capella, but was transferred to Gamma Orionis by the Vienna school of astronomers in the 15th century, and appeared in contemporary reprints of the '' Alfonsine tables''. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiregular Variable
In astronomy, a semiregular variable star, a type of variable star, is a giant or supergiant of intermediate and late (cooler) spectral type showing considerable periodicity in its light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000 days, while the shapes of the light curves may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several magnitudes (usually 1-2 magnitudes in the V filter). Classification The semiregular variable stars have been sub-divided into four categories for many decades, with a fifth related group defined more recently. The original definitions of the four main groups were formalised in 1958 at the tenth general assembly of the International Astronomical Union (IAU). The General Catalogue of Variable Stars (GCVS) has updated the definitions with some additional information and provided newer reference stars where old examples such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
