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Brocchi's Cluster
Brocchi's Cluster (also known as Collinder 399, Cr 399 or Al Sufi's Cluster) is an asterism of 10 stars. Six of the stars appear in a row, across 1.3° of the night sky. The cluster is in the south of the constellation Vulpecula, near the border with Sagitta. Its nickname is the Coathanger. None of these ten stars are believed to be gravitationally bound to each other, thus they are not a star cluster, a fact established by measurements taken by the Hipparcos satellite in 1997. An additional 30 or so much fainter stars are considered by some to be part of the asterism. History It was first described by the Persian astronomer Al Sufi in his ''Book of Fixed Stars'' in 964. In the 17th century, it was independently rediscovered by the Italian astronomer G. B. Hodierna. In the 1920s, Dalmero Francis Brocchi, an amateur astronomer and chart maker for the American Association of Variable Star Observers (AAVSO), created a map of the stars for use in calibrating photometers. In 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observational astronomy, observed pattern or group of stars in the sky. Asterisms can be any identified star pattern, and therefore are a more general concept than the IAU designated constellations, 88 formally defined constellations. Constellations are based upon asterisms, but unlike asterisms, constellations are defined regions with official boundaries which together encompass the entire sky. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye. The Milky Way is a barred spiral galaxy with a Galaxy#Isophotal diameter, D25 isophotal diameter estimated at , but only about 1,000 light-years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc). The Milky Way has several List of Milky Way's satellite galaxies, satellite galaxies and is part of the Local Group of galaxies, forming part of the Virgo Supercluster which is itself a component of the Laniakea Supercluster. It is estimated to contain 100–400 billion stars and at least that number of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterisms (astronomy)
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Asterism may refer to: * Asterism (astronomy), a pattern of stars * Asterism (band), a Japanese rock band * Asterism (gemology), an optical phenomenon in gemstones * Asterism (typography), (⁂) a moderately rare typographical symbol denoting a break in passages See also * * * Aster (other) * Asterisk (other) An asterisk is a typographic symbol, the glyph ⟨*⟩. Asterisk may also refer to: * Asterisk (esports), an esports organization * Asterisk (liturgy), a liturgical implement * Asterisk (PBX), a software implementation of a private branch excha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7 Vul
7 Vulpeculae is a binary star system approximately 910 light years away in the slightly northern constellation of Vulpecula. It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.3. The system currently has a heliocentric radial velocity of −38 km/s. This is a single-lined spectroscopic binary star system with an orbital period of 69.3 days and an eccentricity of 0.16. The visible component is a Be star with a stellar classification of B4–5 III–IVe that appears to be nearing the end of its main sequence lifetime. The system shows a rapid projected rotational velocity of 300 km/s, which is just below the estimated critical velocity for a binary of 367 km/s. There is a small variability in the magnitude over a 0.559-day cycle; this is likely the rotation period of the primary star. The companion is a hot subdwarf, either a subdwarf B or subdwarf O star, with a mass of 48% the Sun's mass. It has a cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bright Giant
A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III. The terms ''giant'' and ''dwarf'' were coined for stars of quite different luminosity despite similar temperature or spectral type (namely K and M) by Ejnar Hertzsprung in 1905 or 1906. Giant stars have radii up to a few hundred times the Sun and luminosities over 10 times that of the Sun. Stars still more luminous than giants are referred to as supergiants and hypergiants. A hot, luminous main-sequence star may also be referred to as a giant, but any main-sequence star is properly called a dwarf, regardless of how large and luminous it is. Formation A star becomes a giant after all the hydrogen available for fusion at its core has been depleted and, as a result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5 Vul
5 Vulpeculae is a single, white-hued star in the northern constellation of Vulpecula. It is situated amidst a random concentration of bright stars designated Collinder 399, or Brocchi's Cluster. This is a faint star that is just visible to the naked eye with an apparent visual magnitude of 5.60. Based upon an annual parallax shift of , it is located around 235 light years from the Sun. It is moving closer with a heliocentric radial velocity of −21 km/s, and will make its closest approach in 2.5 million years at a separation of around . This is a young A-type main-sequence star with a stellar classification of A0 V. It is a rapidly rotating star with a projected rotational velocity of 154 km/s. The star has an estimated 2.33 times the mass of the Sun and about 2.7 times the Sun's radius. It is radiating 34 times the Sun's luminosity from its photosphere at an effective temperature of 8,940 K. A warm debris disk was detected by the Spitzer Space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or lower. The appearance of the red giant is from yellow-white to reddish-orange, including the stellar classification, spectral types K and M, sometimes G, but also S-type star, class S stars and most carbon stars. Red giants vary in the way by which they generate energy: * most common red giants are stars on the red-giant branch (RGB) that are still stellar nucleosynthesis, fusing hydrogen into helium in a shell surrounding an inert helium core * red-clump stars in the cool half of the horizontal branch, fusing helium into carbon in their cores via the triple-alpha process * asymptotic-giant-branch (AGB) stars with a helium burning shell outside a degenerate carbon–oxygen core, and a hydrogen-burning shell just beyo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Vul
4 Vulpeculae is a single, orange-hued star in the northern constellation of Vulpecula. It forms part of the asterism, formerly thought to be an open cluster, called the coathanger or Brocchi's Cluster. The star is faintly visible to the naked eye with an apparent visual magnitude of 5.16. The distance to this star, based upon an annual parallax shift of , is around 260 light years. At the age of about 2.6 billion years old, this is an aging giant star with a stellar classification of K0 III, having exhausted the supply of hydrogen at its core and evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ... off the main sequence. It is now a red clump giant, indicating that it is on the horizontal branch and is generating energy through the fusion of helium at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-type Main-sequence Star
An A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1.7 and 2.1 solar masses (), have surface temperatures between 7,600 and 10,000 K, and live for about a quarter of the lifetime of our Sun. Bright and nearby examples are Altair (A7), Sirius A (A1), and Vega (A0). A-type stars do not have convective zones and thus are not expected to harbor magnetic dynamos. As a consequence, because they do not have strong stellar winds, they lack a means to generate X-ray emissions. Spectral standard stars The revised Yerkes Atlas system listed a dense grid of A-type dwarf spectral standard stars, but not all of these have survived to this day as standards. The "anchor points" and "dagger standards" of the MK spectral classification system among the A-type main-sequence dwarf stars, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-type Main-sequence Star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have strong neutral helium absorption lines, which are most prominent at the B2 subclass, and moderately strong hydrogen lines. Examples include Regulus, Algol A and Acrux. History This class of stars was introduced with the Harvard sequence of stellar spectra and published in the ''Revised Harvard photometry'' catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is 1/5 of the way from type B (or ... [...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] |
Light Year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astronomical Union (IAU), a light-year is the distance that Speed of light, light travels in vacuum in one Julian year (astronomy), Julian year (365.25 days). Despite its inclusion of the word "year", the term should not be misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a Galaxy, galactic scale, especially in public understanding of science, non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years). Definitions As defined by the International Astronomical Union (IAU), the light-year is the product of the Julian year (astronomy), Julian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
