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Hertzsprung Gap
The Hertzsprung gap is a feature of the Hertzsprung–Russell diagram for a star cluster. This diagram is a plot of effective temperature versus luminosity for a population of stars. The gap is named after Ejnar Hertzsprung, who first noticed the absence of stars in the region of the Hertzsprung–Russell diagram between A5 and G0 spectral type and between +1 and −3 absolute magnitudes. This gap lies between the top of the main sequence and the base of red giants for stars above roughly 1.5 solar mass. When a star during its evolution crosses the Hertzsprung gap, it means that it has finished core hydrogen burning. Stars do exist in the Hertzsprung gap region, but because they move through this section of the Hertzsprung–Russell diagram very quickly in comparison to the lifetime of the star (thousands of years, compared to millions or billions of years for the lifetime of the star Table 5.2, Figure 5.2.), that portion of the diagram is less densely populated. Full Her ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Pegasi
Epsilon Pegasi ( Latinised from ε Pegasi, abbreviated Epsilon Peg, ε Peg), formally named Enif , is the brightest star in the northern constellation of Pegasus. With an average apparent visual magnitude of 2.4, this is a second-magnitude star that is readily visible to the naked eye. The distance to this star can be estimated using parallax measurements from the Hipparcos astrometry satellite, yielding a value of around . Nomenclature ''ε Pegasi'' (Latinised to ''Epsilon Pegasi'') is the star's Bayer designation. It bore the traditional name ''Enif'' derived from the Arabic word for 'nose', due to its position as the muzzle of Pegasus. 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 approved by the WGSN; which included ''Enif'' for this star. Other traditional names for the star inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of a star. Yerkes luminosity class IV The term subgiant was first used in 1930 for class G and early K stars with absolute magnitudes between +2.5 and +4. These were noted as being part of a continuum of stars between obvious main-sequence stars such as the Sun and obvious giant stars such as Aldebaran, although less numerous than either the main sequence or the giant stars. The Yerkes spectral classification system is a two-dimensional scheme that uses a letter and number combination to denote the temperature of a star (e.g. A5 or M1) and a Roman numeral to indicate the luminosity relative to other stars of the same temperature. Luminosity class IV stars are the subgiants, located between main-sequence stars (luminosity class&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upsilon Carinae
Upsilon Carinae, Latinized from υ Carinae, is a double star in the southern constellation of Carina. It is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97 and is approximately 1,400 light years (440 parsecs) from Earth. In Chinese, (), meaning '' Sea Rock'', refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810. Consequently, υ Carinae itself is known as (, .) The primary component, υ Carinae A, has a stellar classification of A8 Ib, making it a supergiant star that has exhausted the hydrogen at its core and evolved away from its brief main sequence lifetime as an B-type star. With an apparent magnitude of +3.08, it has an effective temperature of about 7,500 K, giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III, although Mandrini and Niemela (1986) suggested it may be a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Carinae
Iota Carinae (ι Carinae, abbreviated Iota Car, ι Car), officially named Aspidiske , is a star in the southern constellation of Carina. With an apparent visual magnitude of 2.2, it is one of the brighter stars in the night sky. Appearance and location The star and rest of southern Carina never sets on places from about 34° S southwards including Cape Town; its northernmost viewpoints are unobstructed southern horizons near to the 30th parallel north, once a day. The False Cross is an asterism formed from Iota Carinae, Delta Velorum, Kappa Velorum and Epsilon Carinae. It is so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation. The star appears 46.0' (0.7668°) WSW of V357 Carinae, a mid-third-magnitude star, also forming part of the asterism and leading to its long, narrow projection which culminates in Canopus. Nomenclature ''ι Carinae'' ( Latinised to ''Iota Carinae'') is the star's Bayer designation. It has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canopus
Canopus is the brightest star in the southern constellation of Carina (constellation), Carina and the list of brightest stars, second-brightest star in the night sky. It is also Bayer designation, designated α Carinae, which is Romanization, romanized (Transliteration, transliterated) to Alpha Carinae. With a visual apparent magnitude of −0.74, it is outshone only by Sirius. Located around from the Sun, Canopus is a bright giant of spectral type A9, so it is essentially white when seen with the naked eye. It has a luminosity over 10,000 times the luminosity of the Sun, is nine to ten times as mass of the Sun, massive, and has expanded to 71 times the Sun's radius. Its enlarged photosphere has an effective temperature of around . Canopus is undergoing stellar core, core helium fusion, helium burning and is currently in the so-called blue loop phase of its stellar evolution, evolution, having already passed through the red-giant branch after exhausting the h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capella
Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinisation of names, Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the list of brightest stars, sixth-brightest star in the night sky, and the third-brightest in the northern celestial hemisphere after Arcturus and Vega. A prominent object in the northern winter sky, it is Circumpolar star, circumpolar to observers north of 44°N. Its name meaning "little goat" in Latin, Capella depicted the goat Amalthea (mythology), Amalthea that suckled Zeus in classical mythology. Capella is relatively close, at . It is one of the brightest X-ray sources in the sky, thought to come primarily from the stellar corona, corona of Capella Aa. Although it appears to be a single star to the naked eye, Capella is actually a quadruple star system organized in two binary star, binary pairs, made up of the stars Capella Aa, Capella Ab, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Cygni
Gamma Cygni is a star in the northern constellation of Cygnus, forming the intersection of an asterism of five stars called the Northern Cross. It is officially named Sadr , gamma Cygni is its Bayer designation, which that is Latinized from γ Cygni, and abbreviated Gamma Cyg or γ Cyg. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately 1,800 light-years (560 parsecs) from the Sun. It forms the primary or 'A' component of a multiple star system designated WDS J20222+4015 (the secondary or 'BCD' component is WDS J20222+4015BCD, a close triplet of stars 41" away from γ Cygni). Nomenclature ''γ Cygni'' ( Latinised to ''Gamma Cygni'') is the star's Bayer designation. WDS J20222+4015A is its designation in the Washington Double Star Catalog. It bore the traditional name ''Sadr'' (also rendered ''Sadir'' or ''Sador''), derived from the Arabic صدر ''ṣadr'' "chest", the same word which gave rise to the star Schedar ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Arae
Beta Arae is the brightest star in the constellation of Ara. This is a very luminous, relatively young red supergiant with an apparent visual magnitude of 2.84 and an absolute magnitude of −3.494. Its name is a Bayer designation that is Latinized from β Arae, and abbreviated Beta Ara or β Ara. Based on a photogeometric estimation method, it is 710 light-years away, a distance of which interstellar extinction in the line of sight reduces its apparent magnitude by 0.193 magnitudes. Characteristics The spectrum of this star matches a stellar classification of K0/1 Ib, with the luminosity class notation 'Ib' indicating that the star is a supergiant. It has an age estimated at 50 million years, having spent much of its life as a B-type star. Currently, it has expanded to 141 times the Sun's size and is 5,800 times more luminous. Beta Arae is radiating energy from its outer envelope at an effective temperature of , which causes it to take on the orange hue of a K-t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Geminorum
Epsilon Geminorum or ε Geminorum, formally named Mebsuta , is a star in the constellation of Gemini, on the outstretched right 'leg' of the twin Castor. The apparent visual magnitude of +3.06 makes it one of the brighter stars in this constellation. The distance to this star is determined at . Nomenclature ''ε Geminorum'' ( Latinised to ''Epsilon Geminorum'') is the star's Bayer designation. It bore the traditional names ''Mebsuta'', ''Melboula'' or ''Melucta''. ''Mebsuta'' has its roots in an ancient Arabian view where it and the star Mekbuda (Zeta Geminorum) were the paws of a huge lion extending over many present-day constellations. ''Mebsuta'' ('Mabsūṭah' مبسوطة) comes from a phrase referring to the outstretched paw. 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 approved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Puppis
Pi Puppis, Latinisation of names, Latinized from π Puppis, also named Ahadi, is the List of stars in Puppis, second-brightest star in the southern constellation of Puppis. It has an apparent visual magnitude of about 2.7, so it can be viewed with the naked eye at night. Parallax measurements yield an estimated distance of roughly from the Earth. This is a double star with a magnitude 6.86 companion at an angular separation of 0.72 Minute and second of arc#Symbols and abbreviations, arcsecond and a position angle of 148° from the brighter primary. The stellar spectrum, spectrum of Pi Puppis matches a stellar classification of K3 Ib. The Ib luminosity class indicates this a lower luminosity supergiant star that has consumed the hydrogen fuel at its core, stellar evolution, evolved away from the main sequence, and expanded to about 235 times the solar radius, Sun's radius. The effective temperature of the star's outer envelope is approximately , which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hipparcos
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses, proper motions, and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting ''Hipparcos Catalogue'', a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision ''Tycho Catalogue'' of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. ''Hipparcos'' follow-up mission, '' Gaia'', was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
