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50-575: (Redirected from G-III ) For the Misplaced Pages G3 criterion for speedy deletion, see Misplaced Pages:Criteria for speedy deletion § G3 . G3 , G03 , G.III , G.3 or G-3 may refer to: Politics [ edit ] G-3 (Europe) , the top three economies in the European Union G-3 (Latin America) , the grouping of Colombia, Mexico and Venezuela G-3,

100-766: A 1915 German medium bomber G-3 U. S. Army Operations (military staff) G3 battlecruiser , a post First World War design for the Royal Navy that was curtailed by the Washington Naval Treaty G3 (NATO) , the Assistant Chief Of Staff or senior staff officer on Operations and Plans at the division level and higher Gotha G.III , a 1916 German heavy bomber Heckler & Koch G3 , a battle rifle produced by Heckler & Koch Soko G-3, improved variant of Soko G-2 airplane USS  G-3  (SS-31) , an early U.S. Navy submarine Group of Three,

150-456: A Brazilian economy airline, IATA designation G3 Gulfstream III , an American business jet, sometimes abbreviated GIII Automobiles [ edit ] BYD G3 , a 2009–2014 Chinese compact sedan Enranger G3 , a 2014–present Chinese subcompact SUV Pontiac G3 , a 2008–2010 American subcompact car XPeng G3 , a 2018–present Chinese compact electric SUV Rail transportation [ edit ] Gaiemmae Station , station G-03 of

200-454: A digital interchangeable lens camera made by Panasonic PowerPC G3 , a microprocessor branding used by Apple Computer LG G3 , an Android smartphone developed by LG Electronics G3 gaming laptops series from Dell iMac G3 , the first product in Apple's iMac line Media [ edit ] g3 (British magazine) , a UK magazine aimed at lesbian and bisexual women G3 (tour) ,

250-748: A fictional character featured in Kamen Rider Agito G3 (company) , or "Good Governance Group", British corporate security and intelligence company G3 Ministries , Christian organization G-3 visa , a type of non-immigrant visa allowing travel to the United States G-III Apparel Group , a clothing manufacturing company G3 Canada , a Canadian grain company and successor to the Canadian Wheat Board See also [ edit ] 3G (disambiguation) GGG (disambiguation) [REDACTED] Topics referred to by

300-524: A group dispatched to Lebanon in 1958, shortly before the 1958 Lebanon crisis Electronics [ edit ] Canon PowerShot G3 , a digital camera made by Canon G3 power state, in computer ACPI power states G3, a fax encoding format G3, a PBX from the Avaya Definity range Gibson G3 , a 1975 bass guitar iAudio G3, an mp3 player from the Cowon iAudio range Panasonic Lumix DMC-G3 ,

350-527: A live music show and guitar tour organized by Joe Satriani and Steve Vai G3: Genes, Genomes, Genetics , a scientific journal in the discipline of genetics, published by the Genetics Society of America GIII , the alternative title for the third and final film in the Gamera heisei trilogy. Science [ edit ] ATC code G03 Sex hormones and modulators of the genital system , subgroup of

400-526: A luminosity class of IIIb, while a luminosity class IIIa indicates a star slightly brighter than a typical giant. A sample of extreme V stars with strong absorption in He II λ4686 spectral lines have been given the Vz designation. An example star is HD 93129 B . Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum. For example, 59 Cygni

450-665: A nearby observer. The modern classification system is known as the Morgan–Keenan (MK) classification. Each star is assigned a spectral class (from the older Harvard spectral classification, which did not include luminosity ) and a luminosity class using Roman numerals as explained below, forming the star's spectral type. Other modern stellar classification systems , such as the UBV system , are based on color indices —the measured differences in three or more color magnitudes . Those numbers are given labels such as "U−V" or "B−V", which represent

500-493: A sequence from the hottest ( O type) to the coolest ( M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g., A8, A9, F0, and F1 form a sequence from hotter to cooler). The sequence has been expanded with three classes for other stars that do not fit in the classical system: W , S and C . Some non-stellar objects have also been assigned letters: D for white dwarfs and L , T and Y for Brown dwarfs . In

550-457: A series of twenty-two types numbered from I–XXII. Because the 22 Roman numeral groupings did not account for additional variations in spectra, three additional divisions were made to further specify differences: Lowercase letters were added to differentiate relative line appearance in spectra; the lines were defined as: Antonia Maury published her own stellar classification catalogue in 1897 called "Spectra of Bright Stars Photographed with

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600-408: A trio of countries consisting of U.S., China and India, first proposed by chief of world economic forum, deeming these countries to be core economic and geopolitical players in this century. Military [ edit ] AEG G.III , a German World War I heavy bomber Albatros G.III , a 1916 German bomber aircraft Caudron G.3 , a 1913 French single-engined biplane Friedrichshafen G.III ,

650-407: Is a synonym for hotter , while "late" is a synonym for cooler . Depending on the context, "early" and "late" may be absolute or relative terms. "Early" as an absolute term would therefore refer to O or B, and possibly A stars. As a relative reference it relates to stars hotter than others, such as "early K" being perhaps K0, K1, K2 and K3. "Late" is used in the same way, with an unqualified use of

700-554: Is based on spectral lines sensitive to stellar temperature and surface gravity , which is related to luminosity (whilst the Harvard classification is based on just surface temperature). Later, in 1953, after some revisions to the list of standard stars and classification criteria, the scheme was named the Morgan–Keenan classification , or MK , which remains in use today. Denser stars with higher surface gravity exhibit greater pressure broadening of spectral lines. The gravity, and hence

750-545: Is different from Wikidata All article disambiguation pages All disambiguation pages AEG G.III Data from German Aircraft of the First World War General characteristics Performance Armament Aircraft of comparable role, configuration, and era K = Kampfflugzeug (battleplane), renamed as G-class, L = bomber midway between K/G and R-classes Stellar classification In astronomy , stellar classification

800-507: Is listed as spectral type B1.5Vnne, indicating a spectrum with the general classification B1.5V, as well as very broad absorption lines and certain emission lines. The reason for the odd arrangement of letters in the Harvard classification is historical, having evolved from the earlier Secchi classes and been progressively modified as understanding improved. During the 1860s and 1870s, pioneering stellar spectroscopist Angelo Secchi created

850-423: Is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines . Each line indicates a particular chemical element or molecule , with the line strength indicating the abundance of that element. The strengths of

900-576: The He  II λ4541 disappears. However, with modern equipment, the line is still apparent in the early B-type stars. Today for main-sequence stars, the B class is instead defined by the intensity of the He ;I violet spectrum, with the maximum intensity corresponding to class B2. For supergiants, lines of silicon are used instead; the Si ;IV λ4089 and Si III λ4552 lines are indicative of early B. At mid-B,

950-588: The Kelvin–Helmholtz mechanism , which is now known to not apply to main-sequence stars . If that were true, then stars would start their lives as very hot "early-type" stars and then gradually cool down into "late-type" stars. This mechanism provided ages of the Sun that were much smaller than what is observed in the geologic record , and was rendered obsolete by the discovery that stars are powered by nuclear fusion . The terms "early" and "late" were carried over, beyond

1000-501: The Secchi classes in order to classify observed spectra. By 1866, he had developed three classes of stellar spectra, shown in the table below. In the late 1890s, this classification began to be superseded by the Harvard classification, which is discussed in the remainder of this article. The Roman numerals used for Secchi classes should not be confused with the completely unrelated Roman numerals used for Yerkes luminosity classes and

1050-496: The Sun is then G2V, indicating a main-sequence star with a surface temperature around 5,800 K. The conventional colour description takes into account only the peak of the stellar spectrum. In actuality, however, stars radiate in all parts of the spectrum. Because all spectral colours combined appear white, the actual apparent colours the human eye would observe are far lighter than the conventional colour descriptions would suggest. This characteristic of 'lightness' indicates that

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1100-630: The 11 inch Draper Telescope as Part of the Henry Draper Memorial", which included 4,800 photographs and Maury's analyses of 681 bright northern stars. This was the first instance in which a woman was credited for an observatory publication. In 1901, Annie Jump Cannon returned to the lettered types, but dropped all letters except O, B, A, F, G, K, M, and N used in that order, as well as P for planetary nebulae and Q for some peculiar spectra. She also used types such as B5A for stars halfway between types B and A, F2G for stars one fifth of

1150-568: The Anatomical Therapeutic Chemical Classification System G3 star, a subclass of G-class stars in stellar classification Group 3 element of the periodic table G3 medium in embryo culture Transportation [ edit ] Galactic 03 (G03), a suborbital tourist spaceflight on 8 September 2023 Air transportation [ edit ] City Connexion Airlines , a former Burundian airline, IATA designation G3 Gol Transportes Aéreos ,

1200-450: The B2 subclass, and moderate hydrogen lines. As O- and B-type stars are so energetic, they only live for a relatively short time. Thus, due to the low probability of kinematic interaction during their lifetime, they are unable to stray far from the area in which they formed, apart from runaway stars . The transition from class O to class B was originally defined to be the point at which

1250-686: The MK system, a luminosity class is added to the spectral class using Roman numerals . This is based on the width of certain absorption lines in the star's spectrum, which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class  0 or Ia+ is used for hypergiants , class  I for supergiants , class  II for bright giants , class  III for regular giants , class  IV for subgiants , class  V for main-sequence stars , class  sd (or VI ) for subdwarfs , and class  D (or VII ) for white dwarfs . The full spectral class for

1300-558: The Tokyo Metro Ginza Line PRR G3 , an American PRR 4-6-0 locomotive WLWR Class G3 , a Waterford, Limerick and Western Railway Irish steam locomotive LNER Class G3 , a class of British steam locomotives Roads and routes [ edit ] G3 Beijing–Taipei Expressway , incomplete expressway intended to link mainland China and Taiwan Watercraft [ edit ] G3 boats, from Yamaha Motor Corporation Other [ edit ] Kamen Rider G3 ,

1350-515: The alphabet. This classification system was later modified by Annie Jump Cannon and Antonia Maury to produce the Harvard spectral classification scheme. In 1897, another astronomer at Harvard, Antonia Maury , placed the Orion subtype of Secchi class I ahead of the remainder of Secchi class I, thus placing the modern type B ahead of the modern type A. She was the first to do so, although she did not use lettered spectral types, but rather

1400-520: The classes indicate the temperature of the star's atmosphere and are normally listed from hottest to coldest. A common mnemonic for remembering the order of the spectral type letters, from hottest to coolest, is " O h, B e A F ine G uy/ G irl: K iss M e!", or another one is " O ur B right A stronomers F requently G enerate K iller M nemonics!" . The spectral classes O through M, as well as other more specialized classes discussed later, are subdivided by Arabic numerals (0–9), where 0 denotes

1450-637: The colors passed by two standard filters (e.g. U ltraviolet, B lue and V isual). The Harvard system is a one-dimensional classification scheme by astronomer Annie Jump Cannon , who re-ordered and simplified the prior alphabetical system by Draper (see History ). Stars are grouped according to their spectral characteristics by single letters of the alphabet, optionally with numeric subdivisions. Main-sequence stars vary in surface temperature from approximately 2,000 to 50,000  K , whereas more-evolved stars – in particular, newly-formed white dwarfs – can have surface temperatures above 100,000 K. Physically,

1500-525: The demise of the model they were based on. O-type stars are very hot and extremely luminous, with most of their radiated output in the ultraviolet range. These are the rarest of all main-sequence stars. About 1 in 3,000,000 (0.00003%) of the main-sequence stars in the solar neighborhood are O-type stars. Some of the most massive stars lie within this spectral class. O-type stars frequently have complicated surroundings that make measurement of their spectra difficult. O-type spectra formerly were defined by

1550-488: The different spectral lines vary mainly due to the temperature of the photosphere , although in some cases there are true abundance differences. The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O , B , A , F , G , K , and M ,

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1600-716: The extreme velocity of their stellar wind , which may reach 2,000 km/s. Because they are so massive, O-type stars have very hot cores and burn through their hydrogen fuel very quickly, so they are the first stars to leave the main sequence . When the MKK classification scheme was first described in 1943, the only subtypes of class O used were O5 to O9.5. The MKK scheme was extended to O9.7 in 1971 and O4 in 1978, and new classification schemes that add types O2, O3, and O3.5 have subsequently been introduced. Spectral standards: B-type stars are very luminous and blue. Their spectra have neutral helium lines, which are most prominent at

1650-614: The help of the Harvard computers , especially Williamina Fleming , the first iteration of the Henry Draper catalogue was devised to replace the Roman-numeral scheme established by Angelo Secchi. The catalogue used a scheme in which the previously used Secchi classes (I to V) were subdivided into more specific classes, given letters from A to P. Also, the letter Q was used for stars not fitting into any other class. Fleming worked with Pickering to differentiate 17 different classes based on

1700-404: The hottest stars of a given class. For example, A0 denotes the hottest stars in class A and A9 denotes the coolest ones. Fractional numbers are allowed; for example, the star Mu Normae is classified as O9.7. The Sun is classified as G2. The fact that the Harvard classification of a star indicated its surface or photospheric temperature (or more precisely, its effective temperature )

1750-408: The intensity of hydrogen spectral lines, which causes variation in the wavelengths emanated from stars and results in variation in color appearance. The spectra in class A tended to produce the strongest hydrogen absorption lines while spectra in class O produced virtually no visible lines. The lettering system displayed the gradual decrease in hydrogen absorption in the spectral classes when moving down

1800-479: The intensity of the latter relative to that of Si II λλ4128-30 is the defining characteristic, while for late B, it is the intensity of Mg II λ4481 relative to that of He I λ4471. These stars tend to be found in their originating OB associations , which are associated with giant molecular clouds . The Orion OB1 association occupies a large portion of a spiral arm of the Milky Way and contains many of

1850-419: The main sequence). Nominal luminosity class VII (and sometimes higher numerals) is now rarely used for white dwarf or "hot sub-dwarf" classes, since the temperature-letters of the main sequence and giant stars no longer apply to white dwarfs. Occasionally, letters a and b are applied to luminosity classes other than supergiants; for example, a giant star slightly less luminous than typical may be given

1900-485: The modern definition uses the ratio of the nitrogen line N IV λ4058 to N III λλ4634-40-42. O-type stars have dominant lines of absorption and sometimes emission for He  II lines, prominent ionized ( Si  IV, O  III, N  III, and C  III) and neutral helium lines, strengthening from O5 to O9, and prominent hydrogen Balmer lines , although not as strong as in later types. Higher-mass O-type stars do not retain extensive atmospheres due to

1950-401: The pressure, on the surface of a giant star is much lower than for a dwarf star because the radius of the giant is much greater than a dwarf of similar mass. Therefore, differences in the spectrum can be interpreted as luminosity effects and a luminosity class can be assigned purely from examination of the spectrum. A number of different luminosity classes are distinguished, as listed in

2000-619: The proposed neutron star classes. In the 1880s, the astronomer Edward C. Pickering began to make a survey of stellar spectra at the Harvard College Observatory , using the objective-prism method. A first result of this work was the Draper Catalogue of Stellar Spectra , published in 1890. Williamina Fleming classified most of the spectra in this catalogue and was credited with classifying over 10,000 featured stars and discovering 10 novae and more than 200 variable stars. With

2050-428: The ratio of the strength of the He  II λ4541 relative to that of He I λ4471, where λ is the radiation wavelength . Spectral type O7 was defined to be the point at which the two intensities are equal, with the He I line weakening towards earlier types. Type O3 was, by definition, the point at which said line disappears altogether, although it can be seen very faintly with modern technology. Due to this,

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2100-447: The same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=G3&oldid=1259356545 " Category : Letter–number combination disambiguation pages Hidden categories: Short description

2150-410: The simplified assignment of colours within the spectrum can be misleading. Excluding colour-contrast effects in dim light, in typical viewing conditions there are no green, cyan, indigo, or violet stars. "Yellow" dwarfs such as the Sun are white, "red" dwarfs are a deep shade of yellow/orange, and "brown" dwarfs do not literally appear brown, but hypothetically would appear dim red or grey/black to

2200-455: The solar chromosphere, then to stellar spectra. Harvard astronomer Cecilia Payne then demonstrated that the O-B-A-F-G-K-M spectral sequence is actually a sequence in temperature. Because the classification sequence predates our understanding that it is a temperature sequence, the placement of a spectrum into a given subtype, such as B3 or A7, depends upon (largely subjective) estimates of

2250-627: The strengths of absorption features in stellar spectra. As a result, these subtypes are not evenly divided into any sort of mathematically representable intervals. The Yerkes spectral classification , also called the MK, or Morgan-Keenan (alternatively referred to as the MKK, or Morgan-Keenan-Kellman) system from the authors' initials, is a system of stellar spectral classification introduced in 1943 by William Wilson Morgan , Philip C. Keenan , and Edith Kellman from Yerkes Observatory . This two-dimensional ( temperature and luminosity ) classification scheme

2300-463: The table below. Marginal cases are allowed; for example, a star may be either a supergiant or a bright giant, or may be in between the subgiant and main-sequence classifications. In these cases, two special symbols are used: For example, a star classified as A3-4III/IV would be in between spectral types A3 and A4, while being either a giant star or a subgiant. Sub-dwarf classes have also been used: VI for sub-dwarfs (stars slightly less luminous than

2350-483: The term indicating stars with spectral types such as K and M, but it can also be used for stars that are cool relative to other stars, as in using "late G" to refer to G7, G8, and G9. In the relative sense, "early" means a lower Arabic numeral following the class letter, and "late" means a higher number. This obscure terminology is a hold-over from a late nineteenth century model of stellar evolution , which supposed that stars were powered by gravitational contraction via

2400-476: The way from F to G, and so on. Finally, by 1912, Cannon had changed the types B, A, B5A, F2G, etc. to B0, A0, B5, F2, etc. This is essentially the modern form of the Harvard classification system. This system was developed through the analysis of spectra on photographic plates, which could convert light emanated from stars into a readable spectrum. A luminosity classification known as the Mount Wilson system

2450-457: Was not fully understood until after its development, though by the time the first Hertzsprung–Russell diagram was formulated (by 1914), this was generally suspected to be true. In the 1920s, the Indian physicist Meghnad Saha derived a theory of ionization by extending well-known ideas in physical chemistry pertaining to the dissociation of molecules to the ionization of atoms. First he applied it to

2500-488: Was used to distinguish between stars of different luminosities. This notation system is still sometimes seen on modern spectra. The stellar classification system is taxonomic , based on type specimens , similar to classification of species in biology : The categories are defined by one or more standard stars for each category and sub-category, with an associated description of the distinguishing features. Stars are often referred to as early or late types. "Early"

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