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55-450: UMP may refer to: Science [ edit ] Ultra metal-poor star , refers to a type of star with extremely low levels of heavier elements Uniformly most powerful test , in statistical hypothesis testing Uridine monophosphate , a nucleotide Utility maximization problem Organisations [ edit ] Ulba Metallurgical Plant Ulyanovsk Mechanical Plant Union for

110-422: A spheroidal galactic bulge around the galactic core. However, some stars inhabit a spheroidal halo or galactic spheroid , a type of galactic halo . The orbital behaviour of these stars is disputed, but they may exhibit retrograde and/or highly inclined orbits, or not move in regular orbits at all. Halo stars may be acquired from small galaxies which fall into and merge with the spiral galaxy—for example,

165-588: A supermassive black hole at their centers. In our own galaxy, for instance, the object called Sagittarius A* is a supermassive black hole. There are many lines of evidence for the existence of black holes in spiral galaxy centers, including the presence of active nuclei in some spiral galaxies, and dynamical measurements that find large compact central masses in galaxies such as Messier 106 . Bar-shaped elongations of stars are observed in roughly two-thirds of all spiral galaxies. Their presence may be either strong or weak. In edge-on spiral (and lenticular) galaxies,

220-556: A "metal", including chemical non-metals such as oxygen. Observation of stellar spectra has revealed that stars older than the Sun have fewer heavy elements compared with the Sun. This immediately suggests that metallicity has evolved through the generations of stars by the process of stellar nucleosynthesis . Under current cosmological models, all matter created in the Big Bang was mostly hydrogen (75%) and helium (25%), with only

275-678: A Popular Movement or UMP, as of 2015 the former name of the main right-wing political party in France Union of Moderate Parties or UMP, the main Vanuatuan francophone and conservative party United Midwestern Promoters , a racing sanctioning body Universiti Malaysia Pahang , a university in Malaysia Places [ edit ] Indianapolis Metropolitan Airport (by FAA code) Uzumba-Maramba-Pfungwe , Zimbabwe Other [ edit ] Heckler & Koch UMP ,

330-496: A bright pocket of early population stars in the very bright galaxy Cosmos Redshift 7 from the reionization period around 800 million years after the Big Bang, at z = 6.60 . The rest of the galaxy has some later redder population II stars. Some theories hold that there were two generations of population III stars. Current theory is divided on whether the first stars were very massive or not. One possibility

385-425: A density wave, it gets squeezed and makes new stars, some of which are short-lived blue stars that light the arms. The first acceptable theory for the spiral structure was devised by C. C. Lin and Frank Shu in 1964, attempting to explain the large-scale structure of spirals in terms of a small-amplitude wave propagating with fixed angular velocity, that revolves around the galaxy at a speed different from that of

440-406: A flat, rotating disk containing stars , gas and dust , and a central concentration of stars known as the bulge . These are often surrounded by a much fainter halo of stars, many of which reside in globular clusters . Spiral galaxies are named by their spiral structures that extend from the center into the galactic disc. The spiral arms are sites of ongoing star formation and are brighter than

495-452: A hypothetical population of extremely massive, luminous and hot stars with virtually no "metals" , except possibly for intermixing ejecta from other nearby, early population III supernovae. The term was first introduced by Neville J. Woolf in 1965. Such stars are likely to have existed in the very early universe (i.e., at high redshift) and may have started the production of chemical elements heavier than hydrogen , which are needed for

550-580: A later stage in the universe's development. Scientists have targeted these oldest stars in several different surveys, including the HK objective-prism survey of Timothy C. Beers et al . and the Hamburg- ESO survey of Norbert Christlieb et al., originally started for faint quasars . Thus far, they have uncovered and studied in detail about ten ultra-metal-poor (UMP) stars (such as Sneden's Star , Cayrel's Star , BD +17° 3248 ) and three of

605-482: A low relative velocity . It was earlier hypothesized that the high metallicity of population I stars makes them more likely to possess planetary systems than the other two populations, because planets , particularly terrestrial planets , are thought to be formed by the accretion of metals. However, observations of the Kepler Space Telescope data have found smaller planets around stars with

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660-480: A quarter 2.5 billion years ago, until present, where over two-thirds of the galaxies in the visible universe ( Hubble volume ) have bars. The Milky Way is a barred spiral, although the bar itself is difficult to observe from Earth's current position within the galactic disc. The most convincing evidence for the stars forming a bar in the Galactic Center comes from several recent surveys, including

715-407: A range of metallicities, while only larger, potential gas giant planets are concentrated around stars with relatively higher metallicity – a finding that has implications for theories of gas-giant formation. Between the intermediate population I and the population II stars comes the intermediate disc population. Population II, or metal-poor, stars are those with relatively little of

770-501: A submachine gun Umpila language , by ISO 639 code Universal mapping property See also [ edit ] ump , slang term for " umpire " WUMP , a sports radio station in Huntsville, Alabama, known as SportsRadio 730 The UMP Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title UMP . If an internal link led you here, you may wish to change

825-467: A very tiny fraction consisting of other light elements such as lithium and beryllium . When the universe had cooled sufficiently, the first stars were born as population III stars, without any contaminating heavier metals. This is postulated to have affected their structure so that their stellar masses became hundreds of times more than that of the Sun. In turn, these massive stars also evolved very quickly, and their nucleosynthetic processes created

880-594: Is a goal of NASA's James Webb Space Telescope . On 8 December 2022, astronomers reported the possible detection of Population III stars, in a high- redshift galaxy called RX J2129–z8He II. Spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence . Most spiral galaxies consist of

935-584: Is an extremely old spiral galaxy located in the Abell 1689 galaxy cluster in the Virgo constellation. A1689B11 is 11 billion light years from the Earth, forming 2.6 billion years after the Big Bang. In June 2019, citizen scientists through Galaxy Zoo reported that the usual Hubble classification , particularly concerning spiral galaxies , may not be supported, and may need updating. The pioneer of studies of

990-433: Is clear that the elliptical orbits come close together in certain areas to give the effect of arms. Stars therefore do not remain forever in the position that we now see them in, but pass through the arms as they travel in their orbits. The following hypotheses exist for star formation caused by density waves: Spiral arms appear visually brighter because they contain both young stars and more massive and luminous stars than

1045-466: Is that despite their lower overall metallicity, they often have a higher ratio of " alpha elements " (elements produced by the alpha process , like oxygen and neon ) relative to iron (Fe) as compared with population I stars; current theory suggests that this is the result of type II supernovas being more important contributors to the interstellar medium at the time of their formation, whereas type Ia supernova metal-enrichment came at

1100-402: Is that these stars were much larger than current stars: several hundred solar masses , and possibly up to 1,000 solar masses. Such stars would be very short-lived and last only 2–5 million years. Such large stars may have been possible due to the lack of heavy elements and a much warmer interstellar medium from the Big Bang. Conversely, theories proposed in 2009 and 2011 suggest that

1155-524: Is the central value; it is useful to define: R o p t = 3.2 h {\displaystyle R_{opt}=3.2h} as the size of the stellar disk, whose luminosity is L t o t = 2 π I 0 h 2 {\displaystyle L_{tot}=2\pi I_{0}h^{2}} . The spiral galaxies light profiles, in terms of the coordinate R / h {\displaystyle R/h} , do not depend on galaxy luminosity. Before it

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1210-560: Is the oldest and most distant known spiral galaxy, as of 2024.The galaxy has a redshift of 4.4, meaning its light took 12.4 billion years to reach Earth. The oldest grand design spiral galaxy on file is BX442 . At eleven billion years old, it is more than two billion years older than any previous discovery. Researchers believe the galaxy's shape is caused by the gravitational influence of a companion dwarf galaxy . Computer models based on that assumption indicate that BX442's spiral structure will last about 100 million years. A1689B11

1265-446: The Big Bang – are observed in quasar emission spectra . They are also thought to be components of faint blue galaxies . These stars likely triggered the universe's period of reionization , a major phase transition of the hydrogen gas composing most of the interstellar medium. Observations of the galaxy UDFy-38135539 suggest that it may have played a role in this reionization process. The European Southern Observatory discovered

1320-461: The Milky Way galaxy. The Sun is considered as an intermediate population I star, while the sun-like μ Arae is much richer in metals. (The term "metal rich star" is used to describe stars with a significantly higher metallicity than the Sun; higher than can be explained by measurement error.) Population I stars usually have regular elliptical orbits of the Galactic Center , with

1375-555: The Sagittarius Dwarf Spheroidal Galaxy is in the process of merging with the Milky Way and observations show that some stars in the halo of the Milky Way have been acquired from it. Unlike the galactic disc, the halo seems to be free of dust , and in further contrast, stars in the galactic halo are of Population II , much older and with much lower metallicity than their Population I cousins in

1430-554: The Spitzer Space Telescope . Together with irregular galaxies , spiral galaxies make up approximately 60% of galaxies in today's universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters. Spiral galaxies may consist of several distinct components: The relative importance, in terms of mass, brightness and size, of the different components varies from galaxy to galaxy. Spiral arms are regions of stars that extend from

1485-463: The interstellar medium via planetary nebulae and supernovae, enriching further the nebulae, out of which the newer stars formed. These youngest stars, including the Sun , therefore have the highest metal content, and are known as population I stars. Population I stars are young stars with the highest metallicity out of all three populations and are more commonly found in the spiral arms of

1540-415: The bulge of Sa and SBa galaxies tends to be large. In contrast, the bulges of Sc and SBc galaxies are much smaller and are composed of young, blue Population I stars . Some bulges have similar properties to those of elliptical galaxies (scaled down to lower mass and luminosity); others simply appear as higher density centers of disks, with properties similar to disk galaxies. Many bulges are thought to host

1595-446: The center of barred and unbarred spiral galaxies . These long, thin regions resemble a spiral and thus give spiral galaxies their name. Naturally, different classifications of spiral galaxies have distinct arm-structures. Sc and SBc galaxies, for instance, have very "loose" arms, whereas Sa and SBa galaxies have tightly wrapped arms (with reference to the Hubble sequence). Either way, spiral arms contain many young, blue stars (due to

1650-495: The earlier history of the universe. Scientists have found evidence of an extremely small ultra metal-poor star , slightly smaller than the Sun, found in a binary system of the spiral arms in the Milky Way . The discovery opens up the possibility of observing even older stars. Stars too massive to produce pair-instability supernovae would have likely collapsed into black holes through a process known as photodisintegration . Here some matter may have escaped during this process in

1705-505: The early universe. Unlike high-mass black hole seeds, such as direct collapse black holes , they would have produced light ones. If they could have grown to larger than expected masses, then they could have been quasi-stars , other hypothetical seeds of heavy black holes which would have existed in the early development of the Universe before hydrogen and helium were contaminated by heavier elements. Detection of population III stars

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1760-425: The elements heavier than helium. These objects were formed during an earlier time of the universe. Intermediate population II stars are common in the bulge near the centre of the Milky Way , whereas population II stars found in the galactic halo are older and thus more metal-deficient. Globular clusters also contain high numbers of population II stars. A characteristic of population II stars

1815-643: The first 26 elements (up to iron in the periodic table ). Many theoretical stellar models show that most high-mass population III stars rapidly exhausted their fuel and likely exploded in extremely energetic pair-instability supernovae . Those explosions would have thoroughly dispersed their material, ejecting metals into the interstellar medium (ISM), to be incorporated into the later generations of stars. Their destruction suggests that no galactic high-mass population III stars should be observable. However, some population III stars might be seen in high- redshift galaxies whose light originated during

1870-587: The first drawing of Andromeda Galaxy 's spiral structure. In 1852 Stephen Alexander supposed that Milky Way is also a spiral nebula. The question of whether such objects were separate galaxies independent of the Milky Way, or a type of nebula existing within our own galaxy, was the subject of the Great Debate of 1920, between Heber Curtis of Lick Observatory and Harlow Shapley of Mount Wilson Observatory . Beginning in 1923, Edwin Hubble observed Cepheid variables in several spiral nebulae, including

1925-409: The first star groups might have consisted of a massive star surrounded by several smaller stars. The smaller stars, if they remained in the birth cluster, would accumulate more gas and could not survive to the present day, but a 2017 study concluded that if a star of 0.8 solar masses ( M ☉ ) or less was ejected from its birth cluster before it accumulated more mass, it could survive to

1980-514: The form of relativistic jets , and this could have distributed the first metals into the universe. The oldest stars observed thus far, known as population II, have very low metallicities; as subsequent generations of stars were born, they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations of stars from population III. As those population II stars died, they returned metal-enriched material to

2035-483: The galactic disc (but similar to those in the galactic bulge). The galactic halo also contains many globular clusters. The motion of halo stars does bring them through the disc on occasion, and a number of small red dwarfs close to the Sun are thought to belong to the galactic halo, for example Kapteyn's Star and Groombridge 1830 . Due to their irregular movement around the center of the galaxy, these stars often display unusually high proper motion . BRI 1335-0417

2090-404: The galaxy rotates. The arm would, after a few galactic rotations, become increasingly curved and wind around the galaxy ever tighter. This is called the winding problem . Measurements in the late 1960s showed that the orbital velocity of stars in spiral galaxies with respect to their distance from the galactic center is indeed higher than expected from Newtonian dynamics but still cannot explain

2145-411: The galaxy's gas and stars. They suggested that the spiral arms were manifestations of spiral density waves – they assumed that the stars travel in slightly elliptical orbits, and that the orientations of their orbits is correlated i.e. the ellipses vary in their orientation (one to another) in a smooth way with increasing distance from the galactic center. This is illustrated in the diagram to the right. It

2200-501: The high mass density and the high rate of star formation), which make the arms so bright. A bulge is a large, tightly packed group of stars. The term refers to the central group of stars found in most spiral galaxies, often defined as the excess of stellar light above the inward extrapolation of the outer (exponential) disk light. Using the Hubble classification, the bulge of Sa galaxies is usually composed of Population II stars , which are old, red stars with low metal content. Further,

2255-421: The later formation of planets and life as we know it. The existence of population III stars is inferred from physical cosmology , but they have not yet been observed directly. Indirect evidence for their existence has been found in a gravitationally lensed galaxy in a very distant part of the universe. Their existence may account for the fact that heavy elements – which could not have been created in

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2310-428: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=UMP&oldid=1152422201 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Ultra metal-poor star Baade observed that bluer stars were strongly associated with

2365-674: The oldest stars known to date: HE 0107-5240 , HE 1327-2326 and HE 1523-0901 . Caffau's star was identified as the most metal-poor star yet when it was found in 2012 using Sloan Digital Sky Survey data. However, in February ;2014 the discovery of an even lower-metallicity star was announced, SMSS J031300.36-670839.3 located with the aid of SkyMapper astronomical survey data. Less extreme in their metal deficiency, but nearer and brighter and hence longer known, are HD 122563 (a red giant ) and HD 140283 (a subgiant ). Population III stars are

2420-418: The presence of the bar can sometimes be discerned by the out-of-plane X-shaped or (peanut shell)-shaped structures which typically have a maximum visibility at half the length of the in-plane bar. The bulk of the stars in a spiral galaxy are located either close to a single plane (the galactic plane ) in more or less conventional circular orbits around the center of the galaxy (the Galactic Center ), or in

2475-1059: The present day, possibly even in our Milky Way galaxy. Analysis of data of extremely low- metallicity population II stars such as HE 0107-5240 , which are thought to contain the metals produced by population III stars, suggest that these metal-free stars had masses of 20~130 solar masses. On the other hand, analysis of globular clusters associated with elliptical galaxies suggests pair-instability supernovae , which are typically associated with very massive stars, were responsible for their metallic composition. This also explains why there have been no low-mass stars with zero metallicity observed, despite models constructed for smaller population III stars. Clusters containing zero-metallicity red dwarfs or brown dwarfs (possibly created by pair-instability supernovae ) have been proposed as dark matter candidates, but searches for these types of MACHOs through gravitational microlensing have produced negative results. Population III stars are considered seeds of black holes in

2530-412: The rest of the galaxy. As massive stars evolve far more quickly, their demise tends to leave a darker background of fainter stars immediately behind the density waves. This make the density waves much more prominent. Spiral arms simply appear to pass through the older established stars as they travel in their galactic orbits, so they also do not necessarily follow the arms. As stars move through an arm,

2585-462: The rotation of the Galaxy and the formation of the spiral arms was Bertil Lindblad in 1925. He realized that the idea of stars arranged permanently in a spiral shape was untenable. Since the angular speed of rotation of the galactic disk varies with distance from the centre of the galaxy (via a standard solar system type of gravitational model), a radial arm (like a spoke) would quickly become curved as

2640-417: The so-called "Andromeda Nebula" , proving that they are, in fact, entire galaxies outside our own. The term spiral nebula has since fallen out of use. The Milky Way was once considered an ordinary spiral galaxy. Astronomers first began to suspect that the Milky Way is a barred spiral galaxy in the 1960s. Their suspicions were confirmed by Spitzer Space Telescope observations in 2005, which showed that

2695-568: The space velocity of each stellar system is modified by the gravitational force of the local higher density. Also the newly created stars do not remain forever fixed in the position within the spiral arms, where the average space velocity returns to normal after the stars depart on the other side of the arm. Charles Francis and Erik Anderson showed from observations of motions of over 20,000 local stars (within 300 parsecs) that stars do move along spiral arms, and described how mutual gravity between stars causes orbits to align on logarithmic spirals. When

2750-750: The spiral arms, and yellow stars dominated near the central galactic bulge and within globular star clusters . Two main divisions were defined as Population I star and population II , with another newer, hypothetical division called population III added in 1978. Among the population types, significant differences were found with their individual observed stellar spectra. These were later shown to be very important and were possibly related to star formation, observed kinematics , stellar age, and even galaxy evolution in both spiral and elliptical galaxies. These three simple population classes usefully divided stars by their chemical composition or metallicity . By definition, each population group shows

2805-422: The stability of the spiral structure. Since the 1970s, there have been two leading hypotheses or models for the spiral structures of galaxies: These different hypotheses are not mutually exclusive, as they may explain different types of spiral arms. Bertil Lindblad proposed that the arms represent regions of enhanced density (density waves) that rotate more slowly than the galaxy's stars and gas. As gas enters

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2860-472: The surrounding disc because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin. The proportion of barred spirals relative to barless spirals has likely changed over the history of the universe , with only about 10% containing bars about 8 billion years ago, to roughly

2915-422: The theory is applied to gas, collisions between gas clouds generate the molecular clouds in which new stars form, and evolution towards grand-design bisymmetric spirals is explained. The stars in spirals are distributed in thin disks radial with intensity profiles such that with h {\displaystyle h} being the disk scale-length; I 0 {\displaystyle I_{0}}

2970-459: The trend where lower metal content indicates higher age of stars. Hence, the first stars in the universe (very low metal content) were deemed population III, old stars (low metallicity) as population II, and recent stars (high metallicity) as population I. The Sun is considered population I, a recent star with a relatively high 1.4% metallicity. Note that astrophysics nomenclature considers any element heavier than helium to be

3025-572: Was understood that spiral galaxies existed outside of our Milky Way galaxy, they were often referred to as spiral nebulae , due to Lord Rosse , whose telescope Leviathan was the first to reveal the spiral structure of galaxies. In 1845 he discovered the spiral structure of M51, a galaxy nicknamed later as the " Whirlpool Galaxy ", and his drawings of it closely resemble modern photographs. In 1846 and in 1849 Lord Rosse identified similar pattern in Messier 99 and Messier 33 respectively. In 1850 he made

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