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NGC 957
NGC 957 (also known as Collinder 28) is a loosely bound open cluster located in the constellation Perseus. It has an apparent magnitude of 7.6 and an approximate size of 11 arc-minutes. It is young at less than 11 million years old. Location NGC 957 lies in north of the celestial equator, and is therefore easier to be seen from the northern hemisphere. NGC 957 lies 1.5º WNW of NGC 884, which itself is part of the larger Double Cluster. The stars Gamma Persei and Eta Persei point in the general direction of the open cluster. See also *Trumpler 2 - a nearby open cluster References External links * CCD image of NGC 957, Velimir Popov & Emil Ivanov, 2018 Open clusters 957 Year 957 ( CMLVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. Events By place Europe * September 6 – Liudolf, the eldest son of King Otto I, dies of a violent fever nea ... Perseus (constellation) {{star-cluster-stub ... [...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 positions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perseus (constellation)
Perseus is a constellation in the northern sky, being named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as ''Perseus et Caput Medusae''; however, this never came into popular usage. The galactic plane of the Milky Way passes through Perseus, whose brightest star is the yellow-white supergiant Alpha Persei (also called Mirfak), which shines at magnitude 1.79. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightyear
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in 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) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond ( of a degree). This corresponds to astronomical units, i.e. 1\, \mathrm = 1/\tan \left( \ \mathrm \right)\, \mathrm. The nearest star, Proxima Centauri, is about from the Sun. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand. The word ''parsec'' is a portmanteau of "parallax of one second" and was coined by the British astronomer Herbert Hall Turner in 1913 to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though the light-year remains prominent in popula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collinder Catalogue
In astronomy, the Collinder catalogue is a catalogue of 471 open clusters by Swedish astronomer Per Collinder. It was published in 1931 as an appendix to Collinder's paper ''On structural properties of open galactic clusters and their spatial distribution''. Catalogue objects are denoted by ''Collinder'', e.g. "Collinder 399". Dated prefixes include as ''Col + catalogue number'', or ''Cr + catalogue number'', e.g. "Cr 399". Vital statistics * The catalogue contains 471 objects: 452 open clusters, 11 globular clusters, 6 asterisms, 1 stellar moving group, and 1 stellar association. * Objects are spread out across the entire celestial sphere. * Cr 8 is the northernmost Collinder object, located at a declination of +85º in the constellation Camelopardalis. * Cr 411 is the southernmost Collinder object, located at a declination of -79º in the constellation Octans. Collinder objects which are also Messier objects The Collinder Catalogue contains 29 objects which are part of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Cluster
An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. They are loosely bound by mutual gravity, gravitational attraction and become disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a migration to the main body of the galaxy and a loss of cluster members through internal close encounters. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral galaxy, spiral and irregular galaxy, irregular galaxies, in which active star formation is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnitude (astronomy)
In astronomy, magnitude is a unitless measure of the brightness of an object in a defined passband, often in the visible or infrared spectrum, but sometimes across all wavelengths. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. The scale is logarithmic and defined such that a magnitude 1 star is exactly 100 times brighter than a magnitude 6 star. Thus each step of one magnitude is \sqrt \approx 2.512 times brighter than the magnitude 1 higher. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. Astronomers use two different definitions of magnitude: apparent magnitude and absolute magnitude. The ''apparent'' magnitude () is the brightness of an object as it appears in the night sky from Earth. Apparent magnitude depends on an object's intrinsic luminosity, its distance, and the extinction reducing its brightness. The ''absolute'' magnitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minute And Second Of Arc
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 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 957 Map
NGC commonly refers to: * New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy NGC may also refer to: Companies * NGC Corporation, name of US electric company Dynegy, Inc. from 1995 to 1998 * National Gas Company of Trinidad and Tobago, state-owned natural gas company in Trinidad and Tobago * National Grid plc, a former name of National Grid Electricity Transmission plc, the operator of the British electricity transmission system * Northrop Grumman Corporation, aerospace and defense conglomerate formed from the merger of Northrop Corporation and Grumman Corporation in 1994 * Numismatic Guaranty Corporation, coin certification company in the United States Other uses * National Gallery of Canada, art gallery founded in 1880 in Ottawa, Canada * National Geographic, documentary and reality television channel established in the United States in 2001 formerly called National Geographic Channel * Native Girls Code, US non-profit orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 884
NGC 884 (also known as χ Persei) is an open cluster located 7640 light years away in the constellation of Perseus. It is the easternmost of the Double Cluster with NGC 869. NGC 869 and 884 are often designated h and χ Persei, respectively.Some confusion surrounds what Bayer intended by these designations. It is sometimes claimed that Bayer could not have resolved the pair into two patches of nebulosity, and that Chi refers to the Double Cluster and h to a nearby star; see Stephen James O'Meara and Daniel W.E. Green, 2003, "The Mystery of the Double Cluster", ''Sky and Telescope'', Vol. 105, No. 2 (February 2003), p. 116–119. Bayer's ''Uranometria'' chart for Perseus does not show them as nebulous objects, but his chart for Cassiopeia does, and they are described as ''Nebulosa Duplex'' in Schiller's ''Coelum Stellatum Christianum'', which was assembled with Bayer's help; see Morton Wagman, ''Lost Stars'', McDonald & Woodward, 2003, , p. 240. The cluster is about 14 million y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Cluster
The Double Cluster (also known as Caldwell 14) consists of the open clusters NGC 869 and NGC 884 (often designated h Persei and χ (chi) Persei, respectively), which are close together in the constellation Perseus. Both visible with the naked eye, NGC 869 and NGC 884 lie at a distance of about 7,500 light years in the Perseus Arm of the Milky Way galaxy. Membership NGC 869 has a mass of 4,700 solar masses and NGC 884 weighs in at 3,700 solar masses; both clusters are surrounded with a very extensive halo of stars, with a total mass for the complex of at least 20,000 solar masses. They form the core of the Perseus OB1 association of young hot stars. Based on their individual stars, the clusters are relatively young, both 14 million years old. In comparison, the Pleiades have an estimated age ranging from 75 million years to 150 million years. There are more than 300 blue-white super-giant stars in each of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Persei
Gamma Persei (Gamma Per, γ Persei, γ Per) is a binary star system in the constellation Perseus. The combined apparent visual magnitude of the pair is +2.9, making it the fourth-brightest member of the constellation. The distance to this system has been measured using the parallax technique, giving an estimate of roughly with a 4% margin of error. About 4° to the north of Gamma Persei is the radiance point for the annual Perseid meteor shower. This is a wide eclipsing binary system with an orbital period of 5,329.8 days (14.6 years). This eclipse was first observed in 1990 and lasted for two weeks. During an eclipse, the primary passes in front of the secondary, causing the magnitude of the system to decrease by 0.55. The primary component of this system is a giant star with a stellar classification of G9 III. It has a projected rotational velocity of 50.0 km s−1 and a lengthy estimated rotation period of 14.6 years. The classifica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
