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32-410: CETI or Ceti may refer to: Genitive word used to identify the stars belonging to the constellation Cetus Communication with extraterrestrial intelligence Centro de Enseñanza Técnica Industrial Cetí , a fish from Puerto Rico Project CETI , an international initiative to understand the communication of sperm whales Topics referred to by

64-475: A Bayer designation . In this case, the components may be denoted by superscripts. An example of this is α Crucis (Acrux), whose components are α Crucis and α Crucis. Since α Crucis is a spectroscopic binary , this is actually a multiple star. Superscripts are also used to distinguish more distant, physically unrelated, pairs of stars with the same Bayer designation, such as α Capricorni , ξ Centauri , and ξ Sagittarii . These optical pairs are resolvable by

96-578: A binary star. Otherwise, the pair is optical. Multiple stars are also studied in this way, although the dynamics of multiple stellar systems are more complex than those of binary stars. The following are three types of paired stars: Improvements in telescopes can shift previously non-visual binaries into visual binaries, as happened with Polaris A in 2006. It is only the inability to telescopically observe two separate stars that distinguishes non-visual and visual binaries. Mizar , in Ursa Major ,

128-423: A catalogue number unique to that observer. For example, the pair α Centauri AB was discovered by Father Richaud in 1689, and so is designated RHD 1 . Other examples include Δ65, the 65th double discovered by James Dunlop , and Σ2451, discovered by F. G. W. Struve . The Washington Double Star Catalog , a large database of double and multiple stars, contains over 100,000 entries, each of which gives measures for

160-425: A double star was a binary system or only an optical double. Improved telescopes, spectroscopy, and photography are the basic tools used to make the distinction. After it was determined to be a visual binary, Mizar's components were found to be spectroscopic binaries themselves. Observation of visual double stars by visual measurement will yield the separation , or angular distance, between the two component stars in

192-402: A form such as AB-D to indicate the separation of a component from a close pair of components (in this case, component D relative to the pair AB.) Codes such as Aa may also be used to denote a component which is being measured relative to another component, A in this case. Discoverer designations are also listed; however, traditional discoverer abbreviations such as Δ and Σ have been encoded into

224-414: A limiting apparent magnitude of about 9.0. At least 1 in 18 stars brighter than 9.0 magnitude in the northern half of the sky are known to be double stars visible with a 36-inch (910 mm) telescope . The unrelated categories of optical doubles and true binaries are lumped together for historical and practical reasons. When Mizar was found to be a binary, it was quite difficult to determine whether

256-598: A visual double star as a binary star can be achieved by observing the relative motion of the components. If the motion is part of an orbit , or if the stars have similar radial velocities or the difference in their proper motions is small compared to their common proper motion, the pair is probably physical. When observed over a short period of time, the components of both optical doubles and long-period visual binaries will appear to be moving in straight lines; for this reason, it can be difficult to distinguish between these two possibilities. Some bright visual double stars have

288-453: Is also a Seyfert galaxy and thus a bright object in the radio spectrum . Recently, the galactic cluster JKCS 041 was confirmed to be the most distant cluster of galaxies yet discovered. The massive cD galaxy Holmberg 15A is also found in Cetus; as is spiral galaxy NGC 1042 and ultra-diffuse galaxy NGC 1052-DF2 . IC 1613 ( Caldwell 51) is an irregular dwarf galaxy near

320-559: Is different from Wikidata All article disambiguation pages All disambiguation pages Cetus Cetus ( / ˈ s iː t ə s / ) is a constellation , sometimes called 'the whale ' in English. The Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius , Pisces and Eridanus . Cetus

352-477: Is not among the 12 true zodiac constellations in the J2000 epoch , nor classical 12-part zodiac. The ecliptic passes less than 0.25° from one of its corners. Thus the moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly and the southern part of the sun appears in Cetus for about one day each year. Many asteroids in belts have longer phases occulting

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384-451: Is not visible in telescopes. AA Ceti is an eclipsing variable star; the tertiary star passes in front of the primary and causes the system's apparent magnitude to decrease by 0.5 magnitudes. UV Ceti is an unusual binary variable star. 8.7 light-years from Earth, the system consists of two red dwarfs . Both of magnitude 13. One of the stars is a flare star , which are prone to sudden, random outbursts that last several minutes; these increase

416-490: Is often now called the Whale, though it is most strongly associated with Cetus the sea-monster , who was slain by Perseus as he saved the princess Andromeda from Poseidon 's wrath. It is in the middle of "The Sea" recognised by mythologists, a set of water-associated constellations, its other members being Eridanus , Pisces , Piscis Austrinus and Aquarius . Cetus has been depicted in many ways throughout its history. In

448-615: The White Tiger of the West (西方白虎, Xī Fāng Bái Hǔ ). The Tukano and Kobeua people of the Amazon used the stars of Cetus to create a jaguar , representing the god of hurricanes and other violent storms. Lambda, Mu, Xi, Nu, Gamma, and Alpha Ceti represented its head; Omicron, Zeta, and Chi Ceti represented its body; Eta Eri, Tau Cet, and Upsilon Cet marked its legs and feet; and Theta, Eta, and Beta Ceti delineated its tail. In Hawaii ,

480-526: The 17th century, Cetus was depicted as a "dragon fish" by Johann Bayer . Both Willem Blaeu and Andreas Cellarius depicted Cetus as a whale-like creature in the same century. However, Cetus has also been variously depicted with animal heads attached to a piscine body. In Chinese astronomy , the stars of Cetus are found among two areas: the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ ) and

512-420: The beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles between double stars to determine the relative motions of the pairs. If the relative motion of a pair determines a curved arc of an orbit , or if the relative motion is small compared to the common proper motion of both stars, it may be concluded that the pair is in mutual orbit as

544-404: The components of ADS 16402 are ADS 16402A and ADS 16402B; and so on. The letters AB may be used together to designate the pair. In the case of multiple stars, the letters C, D, and so on may be used to denote additional components, often in order of increasing separation from the brightest star, A. Visual doubles are also designated by an abbreviation for the name of their discoverer followed by

576-470: The constellation was called Na Kuhi , and Mira (Omicron Ceti) may have been called Kane . USS Cetus (AK-77) was a United States Navy Crater class cargo ship named after the constellation. Double star This occurs because the pair either forms a binary star (i.e. a binary system of stars in mutual orbit , gravitationally bound to each other) or is an optical double , a chance line-of-sight alignment of two stars at different distances from

608-405: The measures in the plane will produce an ellipse. This is the apparent orbit , the projection of the orbit of the two stars onto the celestial sphere; the true orbit can be computed from it. Although it is expected that the majority of catalogued visual doubles are visual binaries, orbits have been computed for only a few thousand of the over 100,000 known visual double stars. Confirmation of

640-447: The naked eye. Apart from these pairs, the components of a double star are generally denoted by the letters A (for the brighter, primary , star) and B (for the fainter, secondary , star) appended to the designation, of whatever sort, of the double star. For example, the components of α Canis Majoris (Sirius) are α Canis Majoris A and α Canis Majoris B (Sirius A and Sirius B); the components of 44 Boötis are 44 Boötis A and 44 Boötis B;

672-410: The north-western part of Cetus, those with a slightly greater inclination to the ecliptic than the moon and planets. As seen from Mars , the ecliptic (apparent plane of the sun and also the average plane of the planets which is almost the same) passes into it. Mira ("wonderful", named by Bayer : Omicron Ceti , a star of the neck of the asterism) was the first variable star to be discovered and

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704-437: The observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. The only (possible) case of "binary star" whose two components are separately visible to the naked eye is the case of Mizar and Alcor (though actually a multiple-star system), but it is not known for certain whether Mizar and Alcor are gravitationally bound. Since

736-509: The outer edges of the Local Group. The discovery of the nature of the galaxy was accredited to Knut Lundmark and Philibert Jacques Melotte in 1926. UGC 1646 spiral galaxy also lies between the borders of the constellation. It is about 150 million light-years away from us. It can be seen near TYC 43-234-1 star. Cetus may have originally been associated with a whale , which would have had mythic status amongst Mesopotamian cultures. It

768-475: The pair's apparent brightness significantly - as high as magnitude 7. Cetus lies far from the galactic plane , so that many distant galaxies are visible, unobscured by dust from the Milky Way . Of these, the brightest is Messier 77 (NGC 1068), a 9th magnitude spiral galaxy near Delta Ceti . It appears face-on and has a clearly visible nucleus of magnitude 10. About 50 million light-years from Earth, M77

800-409: The prototype of its class, Mira variables . Over a period of 332 days, it reaches a maximum apparent magnitude of 3 - visible to the naked eye - and dips to a minimum magnitude of 10, invisible to the unaided eye. Its seeming appearance and disappearance gave it its name. Mira pulsates with a minimum size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it

832-405: The same term [REDACTED] This disambiguation page lists articles associated with the title CETI . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=CETI&oldid=1175645629 " Category : Disambiguation pages Hidden categories: Short description

864-405: The separation of two components. Each double star forms one entry in the catalog; multiple stars with n components will be represented by entries in the catalog for n −1 pairs, each giving the separation of one component of the multiple star from another. Codes such as AC are used to denote which components are being measured—in this case, component C relative to component A. This may be altered to

896-429: The sky and the position angle . The position angle specifies the direction in which the stars are separated and is defined as the bearing from the brighter component to the fainter, where north is 0°. These measurements are called measures . In the measures of a visual binary, the position angle will change progressively and the separation between the two stars will oscillate between maximum and minimum values. Plotting

928-518: The star 26 Ceti and is a member of the Local Group. NGC 246 (Caldwell 56), also called the Cetus Ring, is a planetary nebula with a magnitude of 8.0, 1600 light-years from Earth. Among some amateur astronomers, NGC 246 has garnered the nickname "Pac-Man Nebula" because of the arrangement of its central stars and the surrounding star field. The Wolf–Lundmark–Melotte (WLM) is a barred irregular galaxy discovered in 1909 by Max Wolf , located on

960-504: The whale") is a very close double star. The primary is a yellow-hued star of magnitude 3.5, 82 light-years from Earth, and the secondary is a blue-hued star of magnitude 6.6. Tau Ceti is noted for being a near Sun-like star at a distance of 11.9 light-years. It is a yellow-hued main-sequence star of magnitude 3.5. AA Ceti is a triple star system; the brightest member has a magnitude of 6.2. The primary and secondary are separated by 8.4 arcseconds at an angle of 304 degrees. The tertiary

992-539: Was discovered by David Fabricius in 1596. α Ceti , traditionally called Menkar ("the nose"), is a red-hued giant star of magnitude 2.5, 220 light-years from Earth. It is a wide double star ; the secondary is 93 Ceti , a blue-white hued star of magnitude 5.6, 440 light-years away. β Ceti , also called Deneb Kaitos and Diphda is the brightest star in Cetus. It is an orange-hued giant star of magnitude 2.0, 96 light-years from Earth. The traditional name "Deneb Kaitos" means "the whale's tail". γ Ceti , Kaffaljidhma ("head of

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1024-507: Was observed to be double by Benedetto Castelli and Galileo . The identification of other doubles soon followed: Robert Hooke discovered one of the first double-star systems, Gamma Arietis , in 1664, while the bright southern star Acrux , in the Southern Cross , was discovered to be double by Fontenay in 1685. Since that time, the search has been carried out thoroughly and the entire sky has been examined for double stars down to

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