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Altair
Altair is the brightest star in the constellation of Aquila (constellation), Aquila and the list of brightest stars, twelfth-brightest star in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinisation of names, Latinised from α Aquilae and abbreviated Alpha Aql or α Aql. Altair is an A-type main-sequence star, A-type main-sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle Asterism (astronomy), asterism; the other two vertices are marked by Deneb and Vega. It is located at a distance of from the Sun. Altair is currently in the G-cloud—a nearby interstellar cloud formed from an accumulation of gas and dust. Altair rotates rapidly, with a velocity at the equator of approximately 286 km/s.From values of ''v'' sin ''i'' and ''i'' in the second column of Table 1, Monnier et al. 2007. This is a significant fraction of the star's estimated breakup speed of 400 km/s. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquila (constellation)
Aquila is a constellation on the celestial equator. Its name is Latin for 'eagle' and it represents the bird that carried Zeus/Jupiter's thunderbolts in Greco-Roman mythology, Greek-Roman mythology. Its brightest star, Altair, is one vertex of the Summer Triangle asterism (astronomy), asterism. The constellation is best seen in the northern summer, as it is located along the Milky Way. Because of this location, many clusters and planetary nebula, nebulae are found within its borders, but they are dim and galaxies are few. History Aquila was one of the 48 constellations described by the second-century astronomer Ptolemy. It had been earlier mentioned by Eudoxus of Cnidus, Eudoxus in the fourth century BC and Aratus in the third century BC. It is now one of the 88 constellations defined by the International Astronomical Union. The constellation was also known as ''Vultur volans'' (the flying vulture) to the Ancient Rome, Romans, not to be confused with ''Vultur cadens'' which wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
γ Aquilae
Gamma Aquilae is a star in the constellation of Aquila. Its name is a Bayer designation that is Latinized from γ Aquilae, and abbreviated gamma Aql or γ Aql. The star is formally known as Tarazed, pronounced . It has an apparent visual magnitude of 2.712, making it readily visible to the naked eye at night. Parallax measurements place it at a distance of from the Sun. The star is drifting closer to the Sun with a radial velocity of −2.8 km/s. Properties Gamma Aquilae is a relatively young star with an age of about 270 million years. Nevertheless, it has reached a stage of its evolution where it has consumed the hydrogen at its core and expanded into what is termed a bright giant star, with a stellar classification of K3 II. The star is now burning helium into carbon in its core. After it has finished generating energy through nuclear fusion, Gamma Aquilae will become a white dwarf. The star has an estimated 3.5 times the mass of the Sun and has expanded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
β Aquilae
Beta Aquilae is a triple star system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from β Aquilae, and abbreviated Beta Aql or β Aql. This system is visible to the naked eye as a point-like source with an apparent visual magnitude of 3.87. Based on parallax measurements, it is located at a distance of 44.4 light-years. It is drifting closer to the Sun with a radial velocity of −40 km/s, and is predicted to approach to within in roughly 207,000 years. Its two visible components are designated Beta Aquilae A and B. The former is formally named Alshain , the traditional name for the system. Nomenclature ''β Aquilae'' (Latinised to ''Beta Aquilae'') is the system's Bayer designation. The designations of the two components as ''Beta Aquilae A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summer Triangle
The Summer Triangle is an astronomical asterism in the northern celestial hemisphere. The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation ( Aquila, Cygnus, and Lyra, respectively). The greatest declination is +45° and lowest is +9° meaning the three can be seen from all places in the Northern Hemisphere and from the home of most people resident in the Southern Hemisphere. The two stars in Aquila and Cygnus represent the head of an eagle and tail of a swan that looks east inscribed into the triangle and forming the altitude of the triangle. Two small constellations, Sagitta and Vulpecula, lie between Aquila in the south of the triangle and Cygnus and Lyra to the north. History The term was popularized by the American author H. A. Rey and the British astronomer Patrick Moore in the 1950s. The name can be found in constellation guidebooks as far back as 1913. The Austrian astronomer ... [...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] |
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, and one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun". Vega was the northern pole star around 12,000 BCE and will be so again around the year 13,727, when its declination will be . Vega was the first star other than the Sun to have its image and spectrum photographed. It was one of the first stars whose distance was estimated through parallax measurements. Vega has functioned as the baseline for calibrating the photometric brightness scale and was one of the stars ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palomar Testbed Interferometer
The Palomar Testbed Interferometer (PTI) was a near infrared, long-baseline stellar interferometer located at Palomar Observatory in north San Diego County, California, United States. It was built by Caltech and the Jet Propulsion Laboratory and was intended to serve as a testbed for developing interferometric techniques to be used at the Keck Interferometer. It began operations in 1995 and achieved routine operations in 1998, producing more than 50 refereed papers in a variety of scientific journals covering topics from high precision astrometry to stellar masses, stellar diameters and shapes. PTI concluded operations in 2008 and has since been dismantled. PTI was notable for being equipped with a "dual-star" system, making it possible to simultaneously observe pairs of stars; this cancels some of the atmospheric effects of astronomical seeing and makes very high precision measurements possible. A groundbreaking study with the Palomar Testbed Interferometer revealed that the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deneb
Deneb () is a blue supergiant star in the constellation of Cygnus. It is the brightest star in the constellation and the 19th brightest in the night sky, with an apparent magnitude slightly varying between +1.21 and +1.29. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. Its Bayer designation is α Cygni, which is Latinised to Alpha Cygni, abbreviated to Alpha Cyg or α Cyg. Deneb rivals Rigel, a closer blue supergiant, as the most luminous first-magnitude star. However, its distance, and hence luminosity, is poorly known; its luminosity is estimated to be between 55,000 and 196,000 times that of the Sun. Distance estimates range from 1,400 to 2,600 light-years; assuming its highest value, it is the farthest star with an apparent magnitude brighter than 2.50. Nomenclature ''α Cygni'' (Latinised to ''Alpha Cygni'') is the star's designation given by Johann Bayer in 1603. The traditional name ''De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Scuti Variable
A Delta Scuti variable (sometimes termed dwarf cepheid when the V-band amplitude is larger than 0.3 mag.) is a class of pulsating star, comprising several sub-classes of object with A- or F-type spectra. The variables follow a period-luminosity relation in certain passbands like other standard candles such as Cepheids. and, together with classical cepheids, are important standard candles. They have been used to establish the distance to the Large Magellanic Cloud, globular clusters, open clusters, and the Galactic Center. The OGLE and MACHO surveys have detected nearly 3,000 Delta Scuti variables in the Large Magellanic Cloud. Typical brightness fluctuations of Delta Scuti variables are from 0.003 to 0.9 magnitudes in V over a period of a few hours, although the amplitude and period of the fluctuations can vary greatly. They are usually A0 to F5 type giant, subgiant, or main sequence stars. The high-amplitude Delta Scuti variables are also called AI Velorum stars, after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Brightest Stars
This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. Stars in binary systems (or other multiples) are listed by their ''total'' or ''combined'' brightness if they appear as a single star to the naked eye, or listed separately if they do not. As with all magnitude systems in astronomy, the scale is logarithmic and inverted i.e. lower/more negative numbers are brighter. Most stars on this list appear bright from Earth because they are nearby, not because they are intrinsically luminous. For a list which compensates for the distances, converting the ''apparent'' magnitude to the ''absolute'' magnitude, see the list of most luminous stars. Measurement The Sun is the brightest star as viewed from Earth, at −26.78 mag. The second brightest is Sirius at −1.46 mag. Fo ... [...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] |
Star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night; their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and traces of heavier elements. Its stellar mass, total mass mainly determines it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
