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Zeta Herculis
Zeta Herculis, Latinized from ζ Herculis, is a multiple star system in the constellation Hercules. It has a combined apparent visual magnitude of 2.81, which is readily visible to the naked eye. Parallax measurements put it at a distance of about from Earth. The primary member is a subgiant star that is somewhat larger than the Sun and has just begun to evolve away from the main sequence as the supply of hydrogen at its core becomes exhausted. It is orbited by a smaller companion star at a mean angular separation of 1.5 arcseconds, which corresponds to a physical separation of about 15 Astronomical Units. This distance is large enough so that the two stars do not have a significant tidal effect on each other. The stars orbit each other over a period of 34.45 years, with a semi-major axis of 1.33" and an eccentricity of 0.46. Component A has a stellar classification of F9 IV. It has about 2.6 times the radius of the Sun and 1.45 times the Sun's mass. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hercules (constellation)
Hercules is a constellation named after Hercules, the Roman mythology, Roman mythological hero adapted from the Greek mythology, Greek hero Heracles. Hercules was one of the 48 constellations listed by the second-century astronomer Ptolemy, and it remains one of the IAU designated constellations, 88 modern constellations today. It is the fifth-largest of the modern constellations and is the largest of List of brightest stars, the 50 which have no stars brighter than apparent Magnitude (astronomy), magnitude +2.5. Characteristics Hercules is bordered by Draco (constellation), Draco to the north; Boötes, Corona Borealis, and Serpens, Serpens Caput to the east; Ophiuchus to the south; Aquila (constellation), Aquila to the southwest; and Sagitta, Vulpecula, and Lyra to the west. Covering 1225.1 square degrees and 2.970% of the night sky, it ranks fifth among the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanometre
330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re, -er, American spelling) is a units of measurement, unit of length in the International System of Units (SI), equal to one billionth (short scale) of a metre () and to 1000 picometres. One nanometre can be expressed in scientific notation as , and as metres. History The nanometre was formerly known as the millimicrometre – or, more commonly, the millimicron for short – since it is of a micron (micrometre), and was often denoted by the symbol mμ or (more rarely and confusingly, since it logically should refer to a ''millionth'' of a micron) as μμ. Etymology The name combines the SI prefix ''nano-'' (from the Ancient Greek , ', "dwarf") with the parent unit name ''metre'' (from Greek , ', "unit of measurement"). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Stars
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough they can gravitationally distort their mutual outer stellar atmospheres. In some cases, these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-type Main-sequence Stars
A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K. Like other main-sequence stars, a G-type main-sequence star is converting the element hydrogen to helium in its core by means of nuclear fusion, but can also fuse helium when hydrogen runs out. The Sun, the star in the center of the Solar System to which the Earth is gravitationally bound, is an example of a G-type main-sequence star (G2V type). Each second, the Sun fuses approximately 600 million tons of hydrogen into helium in a process known as the proton–proton chain (4 hydrogens form 1 helium), converting about 4 million tons of matter to energy. Besides the Sun, other well-known examples of G-type main-sequence stars include Alpha Centauri, Tau Ceti, Capella and 51 Pegasi. The term ''yello ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-type Subgiants
F-type may refer to: *F-type asteroid, a type of carbonaceous asteroid *F-ATPase, a membrane protein *F-type main-sequence star, a hydrogen-fusing star *F-type Prisons, high-security prisons in Turkey *MG F-type Magna, six-cylinder-engined car produced by the MG Car company from October 1931 to 1932 *Jaguar F-Type, a two-seat sports car manufactured by Jaguar Cars *Renault F-Type engine, straight-4 automobile engine from Renault *Empire F type coaster, a type of prefabricated coastal tanker built in the UK during the Second World War *F connector, a commonly used connector for coaxial cable See also *F class (other) *B type (other) B type or Type B may refer to: Astronomy * B-type asteroid, a type of relatively uncommon type of carbonaceous asteroid * B-type giant, a type of blue giant star * B-type star, a type of star Biology * B type blood, a type in the ABO blood group ... * P-type (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 9079
Gliese may refer to: * Rochus Gliese (1891—1978), a German actor, director, production designer, and art director * Wilhelm Gliese (1915–1993), a German astronomer, best known for the Gliese Catalogue of Nearby Stars * Gliese Catalogue of Nearby Stars, a modern star catalog of stars located within 25 parsecs of the Earth * Gliese 163, a red dwarf located 49 light years from the Sun * Gliese 229, a binary system composed of a red dwarf and a brown dwarf about 19 light years away in the constellation Lepus. * Gliese 581, a red dwarf orbited by several extra-solar planets, at least ** Gliese 581d, a planet in the star's habitable zone * Gliese 667, a triple star system in the constellation of Scorpius containing exoplanet GJ 667 Cc in one of the stars' habitable zone * Gliese 682, a red dwarf in the constellation of Scorpius with two candidate planets, one of which is in the star's habitable zone * Gliese 710, a star projected to pass through the Oort Cloud in 1.35 million years ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 678
HD 158614 is a visual binary star system in the equatorial constellation of Ophiuchus. The system is visible to the naked eye with a combined apparent visual magnitude of +5.31. It is located at a distance of 53.3 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −77 km/s and is predicted to come to within in around 196,000 years. The system has been included as a candidate member of the Zeta Herculis moving group. However, chemical abundances appear to rule that out. The pair were found to be a double star by F. G. W. Struve in 1827 and given the catalogue identifier Σ 2173 (now STF 2173). Since then it has completed multiple orbits, yielding orbital elements showing a period of 46.3 years and an eccentricity of 0.17. The two components have similar spectra that match a stellar classification of G9IV-V. They show almost no luminosity variation; one of the pair appears to vary by 0.002 in magnit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 456
Gliese may refer to: * Rochus Gliese (1891—1978), a German actor, director, production designer, and art director * Wilhelm Gliese (1915–1993), a German astronomer, best known for the Gliese Catalogue of Nearby Stars * Gliese Catalogue of Nearby Stars, a modern star catalog of stars located within 25 parsecs of the Earth * Gliese 163, a red dwarf located 49 light years from the Sun * Gliese 229, a binary system composed of a red dwarf and a brown dwarf about 19 light years away in the constellation Lepus. * Gliese 581, a red dwarf orbited by several extra-solar planets, at least ** Gliese 581d, a planet in the star's habitable zone * Gliese 667, a triple star system in the constellation of Scorpius containing exoplanet GJ 667 Cc in one of the stars' habitable zone * Gliese 682, a red dwarf in the constellation of Scorpius with two candidate planets, one of which is in the star's habitable zone * Gliese 710, a star projected to pass through the Oort Cloud in 1.35 million years ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1 Hydrae ...
This is the list of notable stars in the constellation Hydra, sorted by decreasing brightness. See also *List of stars by constellation References Bibliography * * * * * {{Stars of Hydra *List Hydra Hydra generally refers to: * Lernaean Hydra, a many-headed serpent in Greek mythology * ''Hydra'' (genus), a genus of simple freshwater animals belonging to the phylum Cnidaria Hydra or The Hydra may also refer to: Astronomy * Hydra (constel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Reticuli
Zeta Reticuli, Latinized from ζ Reticuli, is a wide binary star system in the southern constellation of Reticulum. From the southern hemisphere the pair can be seen with the naked eye as a double star in very dark skies. Based upon parallax measurements, this system is located at a distance of about from Earth. Both stars are solar analogs that have characteristics similar to those of the Sun. They belong to the Zeta Herculis Moving Group of stars that share a common origin. Nomenclature At a declination of −62°, the system is not visible from Britain's latitude of +53°, so it never received a Flamsteed designation in John Flamsteed's 1712 ''Historia Coelestis Britannica''. The Bayer designation for this star system, Zeta (ζ) Reticuli, originated in a 1756 star map by the French astronomer Abbé Nicolas-Louis de Lacaille. Subsequently, the two stars received separate designations in the Cape Photographic Durchmusterung, which was processed between 1859 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
