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Beta Serpentis
Beta Serpentis, Latinized from β Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with a combined apparent visual magnitude of +3.65. Based upon an annual parallax shift of 21.03 mas as seen from Earth, it is located around 155 light years from the Sun. The system is a member of the Ursa Major Moving Group. Components The visual magnitude +3.68 primary, component A, is either an ordinary A-type main-sequence star or somewhat evolved subgiant with a stellar classification of A2 V or A2 IV, respectively. The star is about 267 million years old with nearly double the mass of the Sun. It is spinning rapidly with a projected rotational velocity of 207 km/s. The secondary component, visual magnitude 9.7 B, lies at an angular separation of 30.6 arc seconds. It is a main-sequence star with a class of K3 V. There is a magnitude +10.98 visual companion, designa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodies) can be used to generate an ephemeris, a table of values giving the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arc Second
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in astro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Serpentis
Epsilon Serpentis, Latinized from ε Serpentis, is a single, white-hued star in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with an apparent visual magnitude of +3.69. Based upon an annual parallax shift of 46.30 mas as seen from Earth, it is located 70 light years from the Sun. It is moving closer to the Sun with a radial velocity of −9 km/s. This is an Am star on the main-sequence with a stellar classification of kA2hA5mA7 V. This notation indicates the spectrum displays the calcium K-line of an A2 star, the hydrogen lines of an A5 star, and the metal lines of an A7 star. It has been examined for the presence of a magnetic field, but the detected level was not statistically significant. Epsilon Serpentis has an estimated 1.82 times the mass of the Sun and 1.78 times the Sun's radius. The star is radiating 12 times the Sun's luminosity from its photosphere at an effective temperature of around 7,928 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Serpentis
Alpha Serpentis or α Serpentis, formally named Unukalhai (), is a double star in the head (Serpens Caput) of the equatorial constellation of Serpens. With an apparent visual magnitude of 2.6, this star is the brightest in the constellation and it can be viewed with the naked eye from most of the Earth. Parallax measurements yield an estimated distance of about from the Sun. Properties Alpha Serpentis is a giant star with a stellar classification of K2IIIbCN1, having consumed the hydrogen at its core and evolved away from the main sequence. It has 1.7 times the mass and 13.5 times the radius of the Sun. The effective temperature of the outer envelope is 4,498 K, giving it an orange hue that is characteristic of a K-type star. It has been classified as a strong CN star, showing a higher than expected strength in the cyanogen bands. This star is radiating about 38 times the luminosity of the Sun, while a further 32 times the Sun's luminosity is being emitted in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Serpentis
Delta Serpentis, Latinized from δ Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). The light from the two stars in the system give a combined apparent magnitude of +3.80, which is bright enough to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 230 light years from the Sun. The system is moving closer with a radial velocity of ~42 km/s, and may come to within in 1.2 million years. The primary, component A, is a yellow-white F-type subgiant with an apparent magnitude of +4.25. It is classified as a Delta Scuti type variable star and its magnitude varies by 0.04 with a period of 0.1557 days. Its binary companion, component B, is also an F-type subgiant which is slightly dimmer, with a magnitude of +5.2. A and B are separated by four arcseconds in the sky, and perform one orbit around their centre of mass once every 3,200 years. Naming It was a member of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa Herculis
Kappa Herculis (κ Herculis, abbreviated Kappa Her, κ Her) is an optical double star in the constellation of Hercules. The two components, Kappa Herculis A (Marsic , the traditional name of the system) and B, were 27.3 arc seconds apart in 2000. Based on parallax measurements from the Hipparcos mission, κ Her A is about 113 parsecs (370 light-years) from the Sun and κ Her B is 600 parsecs (2,000 light-years); more recent parallax measurements suggest that B is around 5% more distant than A. A faint third component Kappa Herculis C is just over 1 arc-minute away. It is at the same distance as κ Her A and has an almost-identical space motion. The star 8 Herculis forms a naked eye pair with Kappa Herculis away. Nomenclature κ Herculis ( Latinised to ''Kappa Herculis'') is the system's Bayer designation. The designations of the components as ''Kappa Herculis A'', ''B'' and ''C'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for mul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heavenly Market Enclosure
The Heavenly Market Enclosure (天市垣, ''Tian Shi Yuan''), is one of the ''San Yuan'' or Three enclosures. Stars and constellations of this group are visible during late summer and early autumn in the Northern Hemisphere (late winter and early spring in the Southern). The Summer Triangle lies directly to the northeast. Asterisms The asterisms are : See also * Twenty-eight mansions * 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, Cygnu ... Chinese constellations {{china-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" (宿 ''xiù'') system also took shape around this period, by the time of King Wu Ding (1250–1192 BCE). Detailed records of astronomical observations began during the Warring States period (fourth century BCE) and flourished from the Han period onward. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Serpentis
Gamma Serpentis (γ Serpentis, γ Ser) is a star in the equatorial constellation Serpens, in the part of the constellation that represents the serpent's head (Serpens Caput). It has an apparent visual magnitude +3.85, which means it is visible to the naked eye. Based upon parallax measurements by the Hipparcos spacecraft, this star is approximately 36.7 light years from Earth. Properties Gamma Serpentis is an ordinary F-type main sequence star with a stellar classification of F6 V. It is larger and more massive than the Sun, with three times the solar luminosity. Based upon its mass, it may have a convection zone in its core region. The projected rotational velocity along the equator is 10.2 km/s. It is younger than the Sun with an estimated age of 3.5 billion years. The effective temperature of the star's outer atmosphere is 6,350 K, giving it the yellow-white-hued glow of an F-type star. Occasionally Gamma Serpentis is listed as having two 10th magnitud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Herculis
Gamma Herculis, Latinized from γ Herculis, is a magnitude 3.74 binary star system in the northern constellation of Hercules. Properties This is known to be a spectroscopic binary system, although there is no information about the secondary component. Based upon parallax measurements, this system is located at a distance of about from the Earth. The spectrum of the primary star matches a stellar classification of A9III, which indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. The effective temperature is about 7,031 K, giving the star a white hue characteristic of A-type stars. It is rotating rapidly with a projected rotational velocity of . The interferometry-measured angular diameter of this star is , which, at its estimated distance, equates to a physical radius of about six times the radius of the Sun. Observations by German astronomer Ernst Zinner in 1929 gave indications that this may be a vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Herculis
Beta Herculis (β Herculis, abbreviated Beta Her, β Her), formally named Kornephoros , or Rutilicus, is a binary star and the brightest star in the northern constellation of Hercules at a base apparent visual magnitude of 2.81. This is a suspected variable star with an apparent magnitude that may rise as high as 2.76. Based upon parallax measurements, it is located at a distance of from the Sun. Although Beta Herculis appears to the naked eye to be a single star, in July 1899 the American astronomer W. W. Campbell discovered from spectroscopic measurements that its radial velocity varies, and concluded that it has a companion. Properties At Palomar Observatory, Antoine Labeyrie and others used speckle interferometry with the Hale Telescope to resolve the system in 1977. The Hipparcos satellite observed the orbital motion of the primary relative to other stars, and an orbit was computed in 2005 using spectroscopic data together with these measur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
