|
Cepheus (constellation)
Cepheus is a constellation in the far northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times. The constellation's brightest star is Alpha Cephei, with an apparent magnitude of 2.5. Delta Cephei is the prototype of an important class of star known as a Cepheid variable. RW Cephei, an orange hypergiant, together with the red supergiants Mu Cephei, MY Cephei, SW Cephei, VV Cephei, and V354 Cephei are among the largest stars known. In addition, Cepheus also has the hyperluminous quasar S5 0014+81, which hosts an ultramassive black hole in its core, reported at 40 billion solar masses, about 10,000 times more massive than the central black hole of the Milky Way, making this among the most massive black holes currently known. This paper does acknowledge the possibility of an optical illusion that would cause an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monarch
A monarch is a head of stateWebster's II New College DictionarMonarch Houghton Mifflin. Boston. 2001. p. 707. Life tenure, for life or until abdication, and therefore the head of state of a monarchy. A monarch may exercise the highest authority and power in the Sovereign state, state, or others may wield that power on behalf of the monarch. Usually a monarch either personally inheritance, inherits the lawful right to exercise the state's sovereign rights (often referred to as ''the throne'' or ''the Crown, the crown'') or is elective monarchy, selected by an established process from a family or cohort eligible to provide the nation's monarch. Alternatively, an individual may self-proclaimed monarchy, proclaim themself monarch, which may be backed and Legitimacy (political), legitimated through acclamation, right of conquest or a combination of means. If a young child is crowned the monarch, then a regent is often appointed to govern until the monarch reaches the requisite adult a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of the world, the lives and activities of List of Greek mythological figures, deities, Greek hero cult, heroes, and List of Greek mythological creatures, mythological creatures, and the origins and significance of the ancient Greeks' own cult (religious practice), cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of myth-making itself. The Greek myths were initially propagated in an oral tradition, oral-poetic tradition most likely by Minoan civilization, Minoan and Mycenaean Greece, Mycenaean singers starting in the 18th century BC; eventually the myths of the heroes of the Trojan War and its after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole
A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary (topology), boundary of no escape is called the event horizon. Although it has a great effect on the fate and circumstances of an object crossing it, it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with thermal radiation, the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly. Obje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S5 0014+81
S5 0014+81 is a distant, compact, hyperluminous, broad-absorption-line quasar, or blazar, located near the high declination region of the constellation Cepheus, near the North Equatorial Pole. Characteristics The object is an OVV (optically violent variable) quasar, a type of blazar. It belongs to the most energetic subclass of active galactic nuclei, which are produced by the rapid accretion of matter by a central supermassive black hole, changing gravitational energy to light energy that can be visible across cosmic distances. In the case of S5 0014+81, it is one of the most luminous quasars known, with a total luminosity of over 1041 watts, equal to an absolute bolometric magnitude of −31.5. If the quasar were at a distance of 280 light-years from Earth, it would give out as much energy per square meter as the Sun does at Earth, despite being 18 million times more distant. The quasar's luminosity is therefore about 3 × 1014 (300 trillion) times that of the Sun, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasar
A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up because of friction and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosity, luminosities thousands of times greater than that of a galaxy such as the Milky Way. Usually, quasars are categorized as a subclass of the more general category of AGN. The redshifts of quasars are of Expansion of the universe, cosmological origin. The term originated as a Contraction (grammar), contraction of "quasi-stellar ''[star-like]'' radio source"—because quasars were first identified during the 1950s as sour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Largest Stars
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the Solar radius, radius of the Sun (approximately ). The angular diameters of stars can be measured directly using Astronomical optical interferometry, stellar interferometry. Other methods can use lunar occultations or from eclipsing binaries, which can be used to test indirect methods of finding stellar radii. Only a few useful supergiant stars can be occulted by the Moon, including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere (Opacity (optics), opacity) differs depending on the wavelength of light in which the star is observed. Uncertainties remain with the membership and order of the lists, especially when deriving various parameters used in calcu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V354 Cephei
V354 Cephei is a red supergiant star located within the Milky Way. It is an irregular variable located over 8,900 light-years away from the Sun. It has an estimated radius of . If it were placed in the center of the Solar System, it would extend to between the orbits of Mars and Jupiter. Identification V354 Cephei is identified as a red supergiant variable star and included on surveys such as IRAS and 2MASS, but prior to its inclusion in the General Catalogue of Variable Stars in 1981, it was referred to only by its listings on relatively obscure catalogs. It is too faint to be included in catalogs such as the Henry Draper Catalogue or Bonner Durchmusterung. It was included on a 1947 Dearborn Observatory survey as star 41575, but that ID is hardly ever used. V354 Cephei has been referred to as Case 75. This is from one of several listings of cool stars made using the Burrell Schmidt telescope at the Warner and Swasey Observatory of Case Western Reserve University, alth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VV Cephei
VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus, approximately 5,000 light years from Earth. It is both a B star and . VV Cephei is an eclipsing binary with the third longest known period. A , it fills its when closest to a companion blue star, the latter appearing to be on the . Matter flows fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MY Cephei
MY Cephei (IRC +60375) is a red supergiant located in open cluster NGC 7419 in the constellation of Cepheus (constellation), Cepheus. It is a semiregular variable star with a maximum brightness of magnitude 14.4 and a minimum of magnitude 15.5. MY Cephei has an unusual spectral type of M7.5, one of the latest spectral types of any supergiant, and is one of the List of most luminous stars, most luminous and List of coolest stars, coolest red supergiants, as well as one of the List of largest stars, largest known stars. If placed at the center of the Solar System, the star's surface would engulf the orbit of Jupiter and possibly even the orbit of Saturn. Observations and variability Observations of the open cluster NGC 7419 in 1954 showed that four of its members were luminous red stars, most likely red supergiants. In addition, an unusually red star was found to be variable and probably an even more luminous supergiant. This star was given the variable star designat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Cephei
Mu Cephei ( Latinized from μ Cephei, abbreviated Mu Cep or μ Cep), also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified. Mu Cephei is visually nearly 100,000 times brighter than the Sun, with an absolute visual magnitude of −7.6. It is also one of the largest known stars with a radius around or over 1,000 times that of the sun (), and were it placed in the Sun's position it would engulf the orbit of Mars and Jupiter. History The deep red color of Mu Cephei was noted by William Herschel, who described it as "a very fine deep garnet colour, such as the periodical star ο Ceti". It is thus commonly known as Herschel's "Garnet Star". Mu Cephei was called ''Garnet sidus'' by Giuseppe Piazzi in his catalogue. An a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars. Classification Stars are classified as supergiants on the basis of their spectral luminosity class. This system uses certain diagnostic spectral lines to estimate the surface gravity of a star, hence determining its size relative to its mass. Larger stars are more luminous at a given temperature and can now be grouped into bands of differing luminosity. The luminosity differences between stars are most apparent at low temperatures, where giant stars are much brighter than main-sequence stars. Supergiants have the lowest surface gravities and hence are the largest and brightest at a particular temperature. The ''Yerkes'' o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RW Cephei
RW Cephei is a hypergiant variable star in the constellation Cepheus (constellation), Cepheus, at the edge of the Sharpless 132 HII region and close to the small open cluster Berkeley 94. One of the List of largest known stars, largest stars known, RW Cephei's radius is more than 1,000 times that of the Sun (), thus larger than the orbit of Jupiter. RW Cephei is also a semi-regular variable star of type Semiregular variable, SRd, meaning that it is a slowly varying yellow giant or supergiant. The visual magnitude range is from 6.0 to 7.6, while the photographic range is from 8.6 - 10.7. The General Catalogue of Variable Stars gives a period of approximately 346 days, but other studies suggest different periods and certainly no strong periodicity. The spectral has been classified as early as G8 and as late as M2, but it isn't clear that there has been actual variation. In the first MK spectral atlas, it was listed M0:Ia. RW Cephei was later listed as the standard st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Red Supergiant")
