Avatar

Which type of galaxies contains primarily population ii metal poor dwarf stars

Which type of galaxies contains primarily population ii metal poor dwarf stars

It has already been noted (e. Elliptical galaxies are nearly pure Population II, while irregular galaxies are spiral galaxy, contains no stars of young age and a low heavy-metal abundance, . , populationII). The numerical values of these exponents can be derived from the detailed behavior of the red and blue GC fractions with galaxy mass and provide a self-consistent set of relations. In spiral galaxies, they tend to be found in the arms and disk. As radially pulsating low-mass horizontal branch (HB) stars in the phase of core helium burning, RR Lyrae variables are good tracers of old ( 10Gyr) and metal-poor populations (i. The period of revolution of the Sun about the galactic center is closest to a. A fraction of these high-mass, metal-free stars enriches the surrounding intergalac-tic medium (IGM) when they go supernova (SN), which occur in stars with ˘<40M in Type II supernovae (SNe) or in stars roughly between 140 M and 260 M in pair-instability SNe (PISNe; Heger & Woosley, 2002). hydrogen and helium) they contain. 1962, ELS): the halo is There is also a weak, blue horizontal branch, so Fornax clearly must contain only a small old, metal-poor component (despite having a globular cluster population). 1 Stellar Evolution and Nucleosynthesis. g. 2, adding to the rapidly growing sample of extremely metal-poor (EMP) stars being identified in Milky Way satellite galaxies. 001 to 0. First Stars / Population III. D) accretion disk. Until recently, it was suspected that such metal-poor galaxies were very old, but because of their small size, it seemed possible that they might have formed so recently that 17. Although a more refined means of classifying stellar populations has since been established (according to whether they are found in the thin disk , thick disk , halo or bulge of the galaxy ), astronomers have continued to coarsely classify stars as either Population I (Pop I) or Population II (Pop II). Population I stars contain approximately 2-3% metals, they are found in the spiral arms or in the disks of galaxies. Nomenclature. II), and dwarf irregular galaxies contain red and blue stars, which indicate a younger population (which he called population I). , White & Frenk 1991; Diemand et al. The number of metal poor stars in galaxies is at least a factor of two less than predicted by the Simple model, exactly similar to the ``G Dwarf The Hubble law applies only to galaxies that are not gravitationally bound to the Milky Way. If these are indeed a distinct population, they would be described as metal-poor (but not as poor as the halo stars), that the dwarf Ellipticals (includes dwarf Spheroidals) of the Local Group show a variety of star-formation histories. while the E0 has primarily Population I stars. Elliptical galaxies are capable of containing all types of stars, however, they tend to be dominated by low-mass, metal-poor, highly ancient Population II stars with relatively low surface temperatures. Intermediate Population I stars are common in the bulge near the centre of our galaxy, whereas Population II stars found in the galactic halo are older and thus more metal-poor. What part of the Milky Way contains mostly old (population II) stars and globular clusters The spherical halo component A small group of stars that has just formed and is still partially enshrouded in its cloud of gas and dust is called “A Photometric Study of the DwarfSpheroidal Galaxies Leo IV and Bootes II. “As far as can be established only two second generation stars were found. Hence, the dIrr’s are also one of the possible sources for the damped Lyα absorption (DLA) systems metal poor stars Question 6 Who first used RR Lyrae variable stars to determine distances in the Milky Way? Harlow Shapley Question 7 Refer to Figure 12-1. These are metal-poor (low metallicity). The smallest ellipticals are called dwarf ellipticals. Note that metallicity also correlates with color: metal poor makes stars bluer; metal rich makes stars redder; Why? Line blanketing: lots of metals (particularly Fe) in the atmospheres of stars absorb preferentially blue light, so the star looks a bit redder. are primarily found in the disk of the galaxy. Globular clusters are made of Population II stars. A division of the stars on basis of age. The Bulge: The central spherical region of our galaxies, which contains mostly old population II stars. A) young and metal-rich. ) are rare Such systems are less affected by reionization and continue to form stars until z = 0, causing higher-metallicity tails. • For the Milky Way companions these range from basically single old stellar populations (Ursa Minor) through to systems like Carina, Fornax and Leo I which have had complex star formation histories, and contain stars as young as ~1 Gyr (or Stellar populations. 1998; Strader et al. Population I stars are younger and generally hotter and bluer than ~[⇑] stars. Although a more refined means of classifying stellar populations has since been established (according to whether they are found in the thin disk, thick disk, halo or bulge of the galaxy), astronomers have continued to coarsely classify stars as either Population I (Pop I) or Population II Early-type Wolf-Rayet stars, which are thought to be responsible for much of the He II λ4686 emission in star-forming galaxies. "Around 400 million years after the Big Bang, the first stars appeared, composed of the elements the Big Bang produced - hydrogen, helium and lithium. It also is thought to hold a massive black hole. The orbits of population I stars The Milky Way: the galaxy we know the most about (by far) Key points: Parts of a spiral galaxy: nucleus, bulge, disk, halo, dark matter; population I and II stars; formation of the Milky Way As we have already discussed, what we see of the Milky Way in visible light is so strongly affected by interstellar dust Although Leo A has one of the lowest metalabundances of known nearby galaxies, detection of tracers of an olderstellar population (RR Lyrae variable stars, horizontal branch stars,and a well-populated red giant branch) indicate that it is not a newlyformed galaxy, as has been proposed for some other similarlow-metallicity star-forming galaxies. 87 An astronomer studying a cluster of galaxies finds a galaxy that is round and has a disk and central bulge like a spiral galaxy but has no spiral arms. Well-studied BCGs include IZw18 (the most metal poor galaxy known), ESO338-IG04 and Haro11. edu is a platform for academics to share research papers. mass and rate of rotation [3, 16]. The past star formation history of an elliptical thus must be very different than that which occurred in the Galaxy. The concept of different populations of stars has undergone considerable change over . B) They have a smooth light distribution with various degrees of elongation from a circular shape. The halo stars are metal-poor (0. The majority of the stars in these examination of the metallicities and kin­ galaxies are more metal-poor than the ematics of the Local Group dwarf irregu-majority of stars examined in the other lar galaxies, and that these galaxies, dwarf galaxies (e. III. Population II stars are older, cooler, less luminous and composed of lighter elements. The importance of this halo in terms of galaxy formation theories was recognized very early on (Eggen et al. The metallicity of these old stars is very low at [Fe/H] ≈ −2.   a. Because of their age, population II stars are found in all galaxies, generally near the galactic bulge. Sol is located 67 ly north of the galactic plane within a roughly 200-ly wide band that is rich in gas, dust, and newborn stars, particularly the associations of extremely bright, bluish, and massive O and B stars and emission nebulae (H II) that light up and define the spiral arms. Capture from other galaxies is increasingly seen as Population II Stars observed in galaxies were originally divided into two populations by Walter Baade in the 1940s. Green Pea galaxies (GPs) are small compact galaxies resembling primordial starbursts. 103 metal-poor, proto-Galactic fragments by the dominant building block: a Based on a comparison of the stellar populations, dark matter, variable stars, and . Astronomy and Astrophysics Review, 2000. Dwarf elliptical galaxies contain only about a few million stars compared to 100 billion in the Milky way. 3 million years. In essence, he first suggested the idea of an LZR. Dwarf ellipticals (dE galaxies) include an assortment of morphological types and range from M V ~ -19 down at least to M V ~ -12 mag, where their numbers are rising steeply and where surveys become seriously incomplete. Most BCGs show signs of recent mergers and/or close interactions. d. 2003; Puzia et al. 9) As Figure 19-19 shows, there are two types of Cepheid variables. Globular clusters and It is admitted, that the galaxy does not contain only Population III stars. The spectrum of a galaxy consists of the sum of the spectra of all its stars. • Spiral galaxies have a variety of star populations. contains stars primarily associated with the disk component of our galaxy. A normal spiral, such as the nearby Andromeda galaxy, has a spherical bulge of stars at its center. The first generation of low-mass, long-lived Pop II stars, the relics of which can be found in the Galactic stellar halo and ultra-faint dwarf satellite galaxies (UFDs), encodes a crucial empirical record of Population II stars. That changed in 1951, when the astronomers Joseph W. • Disk - young stars. The idea here is to scrutinize their chemical abundance patterns and derive constraints on. massive stars in the most metal poor systems, and thus they all have a primary origin (independent of metallicity) at low metallicity – C and N have secondary origin (dependent on metallicity) at higher metallicity The HCN/12CO and HCN/13CO ratios of all 4 early-type galaxies resemble those of nearby Seyfert and dwarf galaxies with normal star formation rates, rather than those of starburst galaxies. (c)Population II stars and tend to be red. However, more detailed studies of star formation histories and chemical evolution properties of populations, like Main Sequence dwarf stars and Red Giant Branch stars, allow a better understanding of the evolutionary context in which AGB stars can be observed. The spheroid is thought to be among the first stellar components to form. Within two billion years, the remaining material settles into a galactic disk. Another prominent member of the Local Group is M33, which is a beautiful Sc spiral galaxy, though it is considerably smaller and less luminous than the Milky Way and M31. The globular cluster M80. These regions have acquired a variety of aliases, all of which refer to essentially the same type of object, dwarf irregular galaxies with spectra dominated by narrow emission lines. The observed old stars are primarily red giants, although a number of horizontal branch stars and red clump Life Cycle of Galaxy. Spiral galaxies like the Milky Way are observed as two basic types. The old stars probably formed from 12 to 6 billion years ago. 03 times solar abundance), but the abundance increases inward toward the center. Ellipsoidally-shaped galaxy, generally tri-axial, consisting primarily of an old ~ (Population II); with properties similar to the bulges of disk galaxies. Giant elliptical galaxies are about 20 times larger than typical elliptical galaxies and often found in clusters of galaxies. Population II stars, on the other hand, were the second type discovered: with much weaker absorption features in their spectra. This is a Type II supernova. Giant H II regions similar to those in spiral galaxy disks are also found in dwarf irregular galaxies. We present a chemical abundance analysis of the brightest star in the newly discovered ultra-faint dwarf galaxy candidate Tucana III. He further noted that while an exclusively old population has been observed, a young population was never seen without an old underlying, fainter, population of red stars, which is called ‘Baade’s Sheet’. (b)a lot of dust, but very little gas. AGB stars are on the whole a very sparse and unrepresentative stellar population in most Local Group galaxies. Dwarf galaxies are the most numerous type of galaxy in the Local Group and provide the opportunity to study a relatively simple, typically metal-poor, environment that is likely similar to the conditions in the early history of all galaxies. Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars? A) Elliptical galaxies B) Barred spiral galaxies C) Starburst galaxies D) Flocculent spiral galaxies Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars? Elliptical galaxies An astronomer studying a cluster of galaxies finds a galaxy that is round and has a disk and central bulge like a spiral galaxy, but has no spiral arms. While population I stars are often present in the discs or the arms of spiral galaxies, Population II stars are found in the nucleus of the galaxy or the globular clusters. A modern de nition of Population II stars would be age 1010 yr, and [Fe=H] −1:0. (b)* Population I stars and tend to be blue. E) red and very low luminous Existence of r-rich stars and r-poor stars No r-process enhanced EMP star is found in dwarf galaxies yet. Academia. D) They cover the entire range of masses from the smallest to the largest galaxies in the universe. attribute this enhancement to Type II SNe . Continue reading "Second-Generation Star Supports Cannibal Theory of Milky Way" to find metal-poor stars in dwarf galaxies were biased in a way that caused the surveys to miss the most metal A small population of galaxies somewhere in between red (late type) and blue (early type) galaxies in the bimodal distribution of galaxy types. Stellar halo (Population II) The stellar halo of the Milky Way includes the system of globular clusters, metal-poor high-velocity stars in the solar neighborhood, and metal-rich dwarf stars seen toward the galactic center. 54, which means that they contain 100 times less heavy elements than the Sun.   IV. dwarf galaxies, as a whole, are very metal deficient, and they host some 30% of the most metal­poor stars observed to date. . However, there is a mystery, explains de Bruyn. 03± and MM(red) h ∼ 1. They are believed to be from Population II Stars. The metal abundance The metal-rich stars in the thin disc have metallicities close to that of the sun (≈ ) and are referred to as population I (pop I) stars while the stars that populate the thick disc are more metal-poor (≈ ) and are referred to as population II (pop II) stars (see stellar population). Redder than Spiral Galaxies. They are mainly to be found in globular clusters, in the halo of the Milky Way. Where would you look in our galaxy to find older, metal-poor stars? A) in the disk and spiral arms B) everywhere in the galaxy C) in the globular clusters in the galactic halo D) only at the galactic center 3. We develop a simple spectral synthesis formulation for all phases of single star evolution from the ZAMS to the white dwarf cooling track that requires only one or two parameters for each choice of age and Most BCGs show signs of recent mergers and/or close interactions. C) a mix of stars with a wide metallicity range. ABUNDANCES IN METAL-POOR DWARF GALAXIES. The Disk: The flat disk-shaped part of the Milky Way, which contains the four spiral arms, and our Sun. Motivated by the Intermediate population II stars are less metal rich than population I stars, are found in the nuclear bulge, are approximately 2–10 billion years old, and have moderately elliptical orbits. e. The gross structural properties of galaxies and their distribution in space are determined primarily by the processes of galaxy formation The Draco Dwarf contains primarily an old population of stars and insignificant amounts of interstellar matter (being basically dust free). This is partly due to ellipticals being characteristically devoid of the interstellar gas and dust clouds necessary to fuel the birth of new stars. Stars observed in galaxies were originally divided into two populations by Walter Baade in the 1940s. Population I stars predominate in the spiral arms of galaxies, while ~[⇑] stars are found in the nuclei of spiral galaxies and in elliptical galaxies POSITION ANGLE Sextans contains several notable deep sky objects, among them the Spindle Galaxy (NGC 3115), the spiral galaxies NGC 3166 and NGC 3169, and the irregular galaxies Sextans A and Sextans B. Very large elliptical galaxies can reach 300 million light years in diameter. In the hierarchical picture of galaxy formation, large galaxies arise through the assembly of smaller aggregates (e. These beauties contain carbon, hydrogen and iron, and are capable of All of the Local Group galaxies contain a significant population of old, relatively metal-poor stars (Population II). (d)Population II stars and tend to be blue. Little interstellar gas and dust, very few young stars (mostly old, red Population II stars). Population I stars are generally found in the disk of spiral galaxies. These types of stars are usually. D) found only in globular clusters. While the auroral lines are routinely observed in local or low redshift, metal-poor, star-forming galaxies (Kennicutt et al. are primarily old low mass stars. Population II stars are older, red stars with lower metallicities and are typically located in globular clusters in ~[⇑] s, The Population I stars are in the disk component of the Galaxy. Type 0 galaxies are the central galaxies of main subhaloes and so can be considered as the principal galaxies of their FOF groups. Elliptical galaxies vary widely in size. 21 0. 02 ± 0. cause of the correlation was a variable ratio of Population I (young, metal-rich) to Population II (old, metal-poor) stars. The structure of the rest of paper is as Request PDF on ResearchGate | Carbon-enhanced metal-poor stars in dwarf galaxies | We investigate the frequency and origin of carbon-enhanced metal-poor (CEMP) stars in Local Group dwarf galaxies Request PDF on ResearchGate | Ultracool Subdwarfs: Metal-poor Stars and Brown Dwarfs Extending into the Late-type M, L and T Dwarf Regimes | Recent discoveries from red optical proper motion and The spheroid is the smooth elliptical distribution of stars found in elliptical galaxies. 2000; Buonanno et al. Which class of galaxies has the greatest range of sizes from largest to the smallest in the universe? 57. 1996a, 1996b). Although a more refined means of classifying stellar populations has since been established (according to whether they are found in the thin disk, thick disk, halo or bulge of the galaxy ), astronomers have continued to coarsely classify stars as either Population I (Pop I, metal-rich) or Population II (Pop II, metal-poor). 25 million years. A ~ is a group of stars or galaxies. The stars we observe throughout the universe today all contain metals, such as Population I stars, which are metal-rich, and Population II stars that are metal-poor. Aller found the first two Population II stars, with about one three-hundredth the amount of iron as our sun. metal-poor as the oldest globular clusters in the Milky Way (½Fe=H < 1:0, >10 Gyr) and are significantly more metal-poor than their associated field-star populations (Strader et al. lifetime of O and B stars), 10,000,000 years Population II. Stars found in the spiral arm s of galaxies, including our Sun, are generally younger and have high metallicities. They are referred to as Population I stars. The high specific frequencies found by us and others in dIrrs (Seth et al. There are also Population II stars near the core of This White Paper summarizes the current knowledge on extremely (sub-SMC) metal poor massive stars, highlighting the most outstanding open questions and the need to supersede the SMC as standard. Finkelstein et al  13 Apr 2010 age of arms of Milky Way (also approx. This classification was made on the basis of the abundance of metal. The host halo and the neighboring halos are then Our sample includes gas-poor dwarf spheroidal galaxies (dSphs) whose star formation ceased shortly after the beginning of the Universe, dSphs with extended star formation that shut down only very recently, and gas-rich dwarf irregular galaxies (dIrrs) that are still forming stars today. Representative objects include stars of type A and later, planetary nebulae, and white dwarfs. It contains over 100 galaxies of many types - including spirals, ellipticals, and irregular galaxies. 5%), and harbour on average are as highly star forming and dusty as those at z ∼ 2 are rare in the local Universe. Cooler gas frag - ments into smaller star-forming clumps than warmer gas, meaning metal-rich stars will generally start smaller than metal-poor ones. Population II stars  I. It is this variation in metallicity that gives rise to the two distinct types of GC in galaxies. This entire sys-tem is embedded in a massive halo of dark material of unknown composition and poorly known spatial distribution. B and early-A blue supergiants (BSGs) in the metal-poor dwarf galaxy NGC 3109. Population I star orbits are orderly: roughly circular orbits close to the mid-plane of the galactic disk. 2004; Georgiev et al. Spirals and Gas. The second column gives [Fe/H], and the third column gives nebular oxygen abundances, when available. In the disc of the Milky Way galaxy, we find metal-rich Population I stars. The chemical abundance of population I stars indicates that the material they formed from had been enriched with material from supernovae. The Milky Way's dwarf galaxies are ideal self-contained systems for us to study early chemical evolution, test theories of galaxy formation on small scales, and understand the assembly history of the Finding the most metal-poor stars in the Milky Way's dwarf galaxies | Carnegie Observatories The stars we observe throughout the universe today all contain metals, such as Population I stars, which are metal-rich, and Population II stars that are metal-poor. Archaeological … - 1903. In general, the stars have a moderately low metallicity (-1 [Fe/H] 0. 2. This would support the view that SF in low-mass systems has Dwarf galaxies, the surviv ors who form the local metal-poor galaxy population, may thus be the principal building blocks of the Universe on lar ge scales. Within the next billion years, globular clusters, the central supermassive black hole and galactic bulge of metal-poor Population II stars form. contain more heavy metals than population I stars. , Simon & Geha, since they formed and evolved in relative 2007; Kirby et al. • The ISM of spiral galaxies is quite complex and show Despite differences in populations the red (mostly ellipticals ). 3 dex, very similar to the typical Milky Way halo abundance pattern. These distinct ages and metallicities in the different Elliptical (E) galaxies are, together with lenticular galaxies (S0) with their large-scale disks, and ES galaxies with their intermediate scale disks, a subset of the "early-type" galaxy population. This pristine population has never been observed, but they left their chemical signature in the next generation of stars. mainly on their structural properties. These low SFefficiencies (compared to the one for the Milky Way disc) adopted forthe dSph galaxies are the main reason for the differences between thetrends of [Ba/Fe] and [Eu/Fe] predicted and observed in these galaxiesand in the metal-poor stars of our Galaxy. They have at best little overall angular momentum , and contain at best a small disk component . It is not clear whether these galaxies are simply outliers among the early and late type distributions, are in transition between the two populations, or are another class of galaxy alltogether. It turns out that their long periods can be accounted for if they are younger than the II-a clusters. In the present contribution, I will mainly concentrate on the dwarf galaxies of the LG. Our own galactic ~, the Local Group, is about 5 million light-years across and contains about 30 galaxies (the largest of which are the Andromeda galaxy, Triangulum, and our Milky Way). These ultra-faint dwarfs are the oldest, most dark matter-dominated, most The LMC also contains a population of massive star clusters that is quite distinct from the Galactic globular or open cluster populations. B) old and metal-poor. all the stars are distributed in a spiral pattern. In astronomy and physical cosmology , the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium . The vast majority of the stars in this galaxy are "metal-poor" stars, which have a very low abundance of elements heavier than helium, compared to stars such as our Sun. However, dwarf spheroidals are found primarily in the cores of dense clusters, indicating they have already undergone signi cant evolution through a. Population II stars. Question 9 Population II stars I. IV.   III. Population II Globular clusters, the central supermassive black hole, and a galactic bulge of metal-poor Population II stars form. Galactic halo. They have a wide range of ages, from 0 to 10 billion years old. Spirals contain both old (Pop II) and young (Pop I) stars. Francesca . III & IV That changed in 1951, when the astronomers Joseph W. Stellar Populations Of Globular Clusters. Young stars in the disc. Daniel Kunth. I fit Dartmouth isochrones to the color-magnitude diagrams (CMD’s) of both objects and derive their ages relative to the old metal poor globular Stars in globular clusters are mainly older metal-poor members of Population II. contains stars primarily associated with the spherical component of our galaxy. Little Galaxies is a weekly meeting where members of CCAPP, OSU Astronomy, and OSU Physics come together to discuss papers and recent developments in astronomy and astrophysics relating to many aspects of "little galaxies", in an informal setting. Mix of young and old stars in the bulge. Thus it contains Population II and/or Population I stars, which have much higher metal content. Globular cluster. Globular clusters are fairly common; there are about 150 to 158 currently known globular clusters in the Milky Way, Early-type, gas-deficient, quiescent dwarfs (such as dwarf ellipticals, dwarf spheroidals, or ultra-compactdwarfs) are primarily found in high-density environments, e. Furthermore, the populations vary with galaxy mass; while the Milky Way Galaxy, a massive example of a spiral galaxy, contains no stars of young age and a low heavy-metal abundance, low-mass galaxies, such as the dwarf irregulars, contain young, low heavy-element stars, as the buildup of heavy elements in stars has not proceeded far in such 4. Population II) Vigorous star formation along the spiral arms. Morphological segregation is not the only indicator of evolution in the cluster, the interstellar Type I supernovae on the other hand, usually occur in the core of elliptical galaxies. Population II. c. The First Stars in the Universe. 2007), and metal-deficie While spiral galaxies are bright, elliptical galaxies are dim. The S0 will be likely to contain supernova remnants while ellipticals never contain supernova remnants. Bar in the Central Bulge. when the stars die they spread these heavier elements into the galaxy around them. 1999; Da Costa & Mould 1988; Durrell et al. Most of these systems ceased star formation long ago, but they retain signatures of their past that can be unraveled by detailed study of their resolved stars. The initial distributions are modified, perhaps Galactic archaeologists uncover new insights into the formation of the earliest stars and galaxies. An old, metal-poor globular cluster in Sextans A and the metallicity floor of globular cluster systems; A metal-poor ultra compact dwarf galaxy at a kiloparsec distance from the low-mass elliptical galaxy FCC47; Satellites of Satellites: The Case for Carina and Fornax; HST resolves stars in a tiny body falling on the dwarf galaxy DDO 68 AGB stars are on the whole a very sparse and unrepresentative stellar population in most Local Group galaxies. ) Globular clusters are old clusters of ~ stars. a, b and d ____ 20. The most metal-poor BCDs (12 + log(O=H) .   II. Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars? 58. It is also home to the most distant known galaxy cluster, CL J1001+0220, and the Cosmos Redshift 7 galaxy, which contains stars formed soon after the Big Bang. We compare projected sightlines from our simulations to the observed metal-poor DLAs and find that our models The galaxy contains Population III (first generation) stars, formed during the reionization epoch, when the Universe was only 800 million years old, not long after the Big Bang. This is probably due to the fact that if a spectrograph was used to detect metals it would see light from the whole galaxy or a large part of it. ” Population I stars. Globular clusters also contain high numbers of population II stars. 250 million years. Population II stars are old, metal-poor stars, and are not found in the disk. 96 0. 42. We confirm the dispersions in very metal-poor GCs (M15, M92 ?). Globular clusters are found in the halo of a galaxy and contain considerably more stars and are much older than the less dense open clusters, which are found in the disk of a galaxy. Thick disks in external galaxies We can look at edge-on external galaxies, such as NGC 891, which is very similar to our Galaxy11 and construct equivalent “BS84” and “G84” models. These old stars, however, are not standard Population II stars as in the Milky Way Galaxy, because spectroscopic analysis shows that many of them have a metallicity like the Sun, or even a greater abundance of heavy elements. Stars like the sun consist of only about 2% metals (the rest being hydrogen and helium); these stars are called “population I” stars and are found primarily in the disk of spiral galaxies. On the basis of the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies3 claimed that the true Galactic building blocks must have been vastly different from We measure an iron abundance of [Fe/H] = -3. Population III Stars and the Big Bang Model. SPIRAL GALAXIES • They have flat, disk-like shapes. One of the beauties of some star-forming dwarf galaxies is that they can be so metal-poor that their abundance analysis bear strong cosmological implications. , Einasto et al. 2010, 2014) possess My main research focuses on massive stars (ultracompact HII regions and OB-type stars) and star clusters in our Milky Way galaxy and nearby star-forming galaxies. , in the vicinity of massive galaxies in groups and clusters. CCD observations of the populous clusters reveal a bimodal age distribution, with virtually all of the clusters being either younger than 3 Gyr old or older than 12 Gyr [10]. Third, the strength of a Ca II index sensitive to hot stars does not jibe with the predicted number of A-type horizontal branch stars. Further, the  Although a more refined means of classifying stellar populations has since been halo or bulge of the galaxy), astronomers have continued to coarsely classify stars as Pop II stars are metal-poor, with metallicities ranging from approximately primarily in Type II supernova explosions (the explosions of massive stars  Dwarf ellipticals, which are very common, may contain only 1/100,000th as many stars as the Milky Way! As you might expect, the bulge is composed primarily of Population II stars. I use space- and ground-based imaging and spectroscopic data to study how those massive systems regulate star formation and evolution activities in galaxies. In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium. 0. II   d. But evidence is mounting that the for-mation of our galaxy was less straightfor-ward than this model suggests. Since light metals are produced primarily in Type II supernova explosions (the explosions of massive stars which have lifetimes of only a few million years), while the heavier elements can only be produced in Type Ia supernova explosions (the explosion of a much older white dwarf in a binary system ), The largest range of sizes of galaxies is found in which class of galaxies? 56. The average [Fe/H] of their stars may be as low as about −2. Chapter 17: A Diversity of Galaxies Describing Galaxies It appears that little star formation is still going on in most ellipticals. The halo includes the metal-poor subdwarfs in the solar neighborhood that have large velocities with respect to the sun, globular clusters which are the true tracers of the halo and contain Population II cepheids, and RR Lyrae variables among other stars. , 2008). 2 billion years. Because they swarm around the center like bees around a hive, the globular clusters were used to locate the center of the Galaxy as described above. For this purpose, the stars with the lowest CaT metallicities were followed up with high resolution spectroscopy in order to accurately determine metallicities and abundances of several other elements. The distributions of stars in the Galaxy over position and velocities are linked through gravitational forces, and through the star formation rate as a function of position and time. Then, second-generation Population II (Pop II) stars formed from sufficiently metal-enriched gas elements. Extreme population II stars are the most metal-poor stars, are found in the halo and in globular clusters, are about 10–14 billion years old and have highly elliptical orbits. 4. “Among the new extremely metal-poor stars discovered in these dwarf galaxies, three have a relative amount of heavy chemical elements between only 1/3000 and 1/10 000 of what is observed in our white dwarf stars 4. The Milky Way (MW) has an extended halo consisting of old and metal-poor stars, the so-called Population-II stars (Baade 1944). While star formation in the outer halo largely ceased more than 10^10 years ago, the situation in the inner kpc of the galaxy is not so clear. 5) compared to the Sun. 2 Measuring metallicities of stellar populations. The creation of a supermassive black hole appears to play a key role in actively regulating the growth of galaxies by limiting the total amount of additional matter added. A the most metal-poor field stars agrees. (Population I) Old stars in globular clusters in the halo. are located in globular 2011). III & IV   b. 13. Astronomers refer to this as the missing G-dwarf star. Whatever the formation mechanism, all of the different types of elliptical galaxies contain significantly less dust and gas than spiral galaxies and irregular galaxies, and certainly not enough to support much star formation at present times. Type c spiral galaxies have the most gas and dust. Some astronomers have identified an intermediate population of stars, variously called the "metal weak thick disk", the "intermediate population II", et al. are located primarily in the halo. Young metal rich stars are called Population I and old metal poor stars are called ~. contains a (small) population of glob- . They are particularly found in the spiral arms. (see 4d(ii) below for further discussion of vertical disk structure)  4 Feb 2019 Type Ia supernovae are an additional important source of elements. Dwarf ellipticals, which are very common, may contain only 1 Galaxy Cosmos Redshift 7 contains old Population II (metal-poor) and Population III (extremely metal-poor) stars, according to astronomers, and is three times brighter than the brightest distant galaxies (redshift, z > 6) detected up to the time of its discovery. In fact, elliptical galaxies contain primarily old, red stars (also known as Population II stars). 25 billion years. It is composed primarily of an old, metal-poor, population of stars typically having ages „ 12 Gyr or more. for the older stars, which are primarily those stars of later spectral types. Metals make things difficult for star growth, for two reasons. Understanding the properties of stars and gas at low metallicity is of large relevance for a variety of fields in astrophysics, since it relates to multiple topical questions which range from understanding the properties of galaxies that contributed to cosmic reionization to the evolution of metal-poor massive stars that give rise to the The ICM contains as many metals as all the stars in all the cluster galaxies Abundance analysis suggests the metals were generated by Type II (core collapse) SN the ICM and its metals probably originated from starburst driven superwinds. A rich, regular cluster of galaxies differs from a rich, irregular cluster in that it D) Has fewer spirals and more ellipticals and S0 galaxies than an irregular cluster 17. Populations I and II Stars. Populations of Galaxies –Done primarily for stars in solar neighborhood (detected Heavy Metal Enrichment •A population will be enriched with metals • Two more massive galaxies: – Irregular Large MagellanicCloud – Small (dwarf) elliptical galaxy M32 • The rest are dwarf galaxies (dI, dE, dSph) with MV> -18 The Local Group Inventory • The Local Group does not contain: – Blue compact dwarf galaxies – Dwarf spirals – Massive ellipticals – Active galaxies The Large MagellanicCloud (LMC) II, Intermediate Population II, and Halo Population II. – Thick spheroid of stars with little gas or dust. Significant Metal poor stars; GCs, dwarfs; low-density hot gas . A Dwarf Galaxy Reveals The Universe's Secrets The most ancient oxygen-deficient galaxies are so remote and faint that they are almost undetectable. I & II   c. Very metal-poor damped Lyα systems (DLAs) recently identified at z ∼ 2 may represent the gas that formed at least some of the observed stars in UFDs. extensive studies on the stellar population of Crater II. " There are two types of dwarf galaxies: gas-poor dwarf spheroidals (dSph), and gas-rich irregulars (dIrr). are located in globular clusters. 5” stars (Mackey et al. First, "seed" proto-stars formed from the collapsing core of gas clouds that go through a stage as a flattened disc, with two The Milky Way may actually contain as much as the mass of a trillion suns like Sol, although the 400 billion, estimated luminous stars mass only about 175 billion suns. The most metal-poor galaxies. GPs are generally metal poor (oxygen abundance ~20% solar), The Milky Way (MW) has an extended halo consisting of old and metal-poor stars, the so-called Population-II stars (Baade 1944). e. Lyman-alpha emitters are typically young, extremely distant, low-mass galaxies that have the highest specific star formation rate of any galaxies known. A modi ed method is presented which does not require use of the Balmer jump as an independent T eff indicator, as in previous studies. What is the star's absolute magnitude?-1 Question 8 The chemical abundance of population I stars they contain a significant fraction of metal-poor stars with an enhanced α-element abundance consistent with the stellar MW halo, indicating that the dSph systems may be important contributors to the MW. It also implies that the UVX in galaxies is not produced by metal poor subpopulations similar to the clusters. What galactic type contains both the A high-mass star reaches the end of its life and forms an iron core. In general dSph galaxies contain little or no gas, and no H II regions. The G Dwarf Problem Exists in Other Galaxies. The proximity 2003), corresponding to the magnitudes of stars well below the Population II Furthermore, the LG contains a variety of different galaxy types. Some stars have even fewer metals, perhaps only one one-hundredth the amount found in the sun. Chamberlain and Lawrence H. We determine stellar e ective tem-peratures, gravities, metallicities, reddening, and luminosities, and combine our sample Among them are extremely metal-poor stars found in the halo of the Milky Way. (2001) also noted that there exist two different populations, suggesting that while the giant galaxies are virialized, the dwarf population is still in-falling. [9] Here we report the kinematic detection of a stellar stream in one of the satellite galaxies of Andromeda, the dwarf spheroidal Andromeda II, which has a mass of only 10 7 solar masses in stars 9 The blue solid line is the isochrone of a 13-Gyr old meta-poor population of stars, precisely what dominates faint MW dwarf galaxies. IV   e. b. Their stars have lower metal abundances than Sun-like stars because they formed at an earlier epoch when the interstellar medium was less en-riched in heavy elements (4). 1962, ELS): the halo is The lowest mass galaxies are dwarf irregular (dI) and dwarf spheroidal (dSph) type galaxies. The youngest ones are in the spiral arms. Finally, we predict the existence of extremely low metallicity stars in LG UFD galaxies that preserve the pure chemical signatures of Population III nucleosynthesis. The disk contains a large quantity of . Stars in globular clusters are mainly older metal-poor members of Population II. The young metal-rich stars in the Milky Way are called Population I stars, and the old metal-poor stars are called Population II stars; following this terminology, the stars with no metals at all—the very first generation—are sometimes called Population III stars. The stellar population of Leo T consists of both old and young stars. The largest known galaxies are the so-called cD, or supergiant, ellipticals. 5. These may represent high-luminosity blue compact galaxies. observations of ultrafaint dwarfs (UFDs), the least massive known galaxies. ” I present a photometric study of the ultra-faint dwarf (UFD) galaxies Leo IV and Boötes II in the V and IC filters. A team led by David Sobral has just spectroscopically confirmed that one of the most distant, luminous galaxies in the Universe may be housing a group of Population III stars, which would make it specific frequencies such as to preserve the observed high ratio between metal-poor GCs and metal-poor field stars in massive galaxies. 1. !type. 5, a value slightly less than for most metal­poor, old It is therefore essential to test the reliability of the CaT metallicity estimate and confirm or disprove the existence of extremely metal poor stars in classical dwarf spheroidal galaxies (dSphs). Thus, most of the galaxy's mass must be composed of "dark" matter, of which brown dwarfs, neutron stars, black holes, gas, and dust are estimated to make up only a minor share. II. Outline The disk population Eggen, Lynden-Bell and Sandage collapse model The thick disk Globular clusters The Sagittarius dwarf. BCDs contain much less heavy elements than the majority of high-z galaxies. Most of the LG galaxies are smaller ellipticals, sometimes called dwarf ellipticals and sometimes dwarf spheroidals. Blue compact dwarf galaxies (BCD galaxies) are small compact galaxies. The only difference between these low mass dSphs and dIs seems to be the presence of gas and current star formation in dIs. metal-poor stars, as well as ∼160 globular clusters and a small number of satellite dwarf galaxies. 3. Both the largest and the smallest known galaxies are elliptical. like stars in globular clusters, old; metal poor. But these “Population II. cases. In dwarf galaxies, the GCs are also more metal-poor than the field stars on average. 41. and globular clusters (open circles) belonging to early-type dwarf galaxies. While Population III stars were presumably very mas-sive, shortlived objects, stars at the low-mass end of the subsequent, “second” generation of early star formation may still exist today and can be observed as extremely metal-poor stars (Mackey, Bromm, & Hernquist 2003). The cluster contains not only galaxies filled with stars but also gas so hot it glows in X-rays . However, more detailed studies of star formation histories and chemical evolution properties of populations, such as main sequence dwarf stars and red giant branch stars, allow a better understanding of the evolutionary context in which AGB stars can be observed. Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars? Elliptical galaxies An astronomer studying a cluster of galaxies finds a galaxy that is round and has a disk and central bulge like a spiral galaxy, but has no spiral arms. radii in local group galaxies indicate that the paucity of metal poor stars applies globally, rather than only in the nuclei. A handful of of these stars in type II clusters with intermediate metal abundance (their group II-a). subpopulations of metal-poor (blue) and metal-rich (red) GCs. Chemical Evolution of Dwarf Galaxies and Stellar Clusters. The HCN/HCO+ ratio is relatively high in the 3 galaxies with detected HCN emission, mimicking the behaviour in other star-forming galaxies but being higher than in starburst galaxies. Most emphasis has been laid on the role of dwarf spheroidals in galaxy merging. Therefore some of the local group galaxies show small blue shifts. 7:6) have therefore been pointed out as particularly good candidate \primeval" galaxies in the nearby Universe that started to form stars no more than 40Myr ago (IT99). 1974) that dSphs predominantly lie close to our galaxy (< 250kpc away), and dIs The Local Group contains approximately 40 known members, although more, small faint dwarf galaxies probably remain to be discovered in the group. There’s also a hint of the Blue Horizontal Branch visible (at gmag ~ 21. During 1944, Walter Baade categorized groups of stars within the Milky Way into stellar Between the population types, significant differences were found with their Observation of stellar spectra has revealed that stars older than the Sun have fewer Population II, or metal-poor, stars are those with relatively little metal. UV, optical and infrared spectra of galaxies contain a wealth of . The total mass of the stellar halo is only about 10^9 M_sun . Spectroscopic analysis reveal that these stars are metal poor. Aside form the three prominent spiral galaxies, the Milky Way, M31 and M33, its population consists primarily of low mass irregular and dwarf spheroidal (DSph) galaxies. With the model of heavy element formation in supernovae, this suggests that the gas from which they formed had been seeded with the heavy elements formed from previous giant stars. See only old Pop II stars Irregulars: Can range up to 90% gas Often a great deal of on-going star formation Dominated by young Pop I stars Dwarf Irregulars: Very metal poor (<1% solar) Forming stars for the first time only now. dark matter, dwarf galaxies, galaxy kinematics and dynamics, Local Group, metal-poor stars Abstract The lowest luminosity (L<105 L ) Milky Way satellite galaxies rep-resent the extreme lower limit of the galaxy luminosity function. The mean metallicity of the stellar populations of dwarf galaxies shows a The dependence of SN or T on galaxy type has been reviewed by Brodie  eg classification bins : simple E0-6 compared with all the spiral types not just smooth, considerable Wide range in stellar populations: "hot" mainly dispersion supported bulge and halo stars. Young (1999) looked for neutral hydrogen in and around Fornax and found none, to the column density limit of 4 × 10 18 cm -2 in the galaxy center, and 10 19 cm -2 out to the tidal radius. First, metals cause gas to cool faster. Download with Google Download with Facebook or download with email. For M31 and the Galaxy, these stars are found predominantly in the stellar halo, while for the dwarfs, Population II stars tend to be the dominant component. Their photometric and pulsation properties The very brightest of them, called cD galaxies, are found at the centers of clusters, and are among the most luminous galaxies in the Universe. Spiral galaxiesSpiral galaxies. As the IGM condenses into galaxies it contains the primordial abundances of H, D, 3 He, 4 He and 7 Li. (A possibly helpful mnemonic: II stars are older than I stars because II is bigger than I. C) gravitational influence on visible stars. For this reason they are now observed to consist primarily of old, red, population II stars. Do they contain the purest, most metal-poor, most ancient populations known? In the Milky Way the stellar halo consists of old, metal-poor stars and globular Prominent morphological evidence of ongoing dwarf galaxy accretion has Classical bulges (found in early-type to Sbc spirals) resemble elliptical galaxies in their bulges having formed 10 to 30% of their mass in the past 1 to 2 Gyr ( Thomas  Rotationally supported, lots of gas, dust, star formation occurs in disks, Bulge- oldish stars-tends to be metal poor. Because of the dominance of metal rich stars, primordial galaxies will have a plentiful dust supply early in their star formation history, and thus will probably have weak Lyα emission, as is apparently observed. The other type is the barred spiral, which has an elongated central bulge called a bar. Scalo, 1980a), as metals are more depleted in cold clouds than in the warm  Our galaxy, the Milky Way, contains maybe 400 billion stars (plus or minus 200 O and B stars and emission nebulae (H II) that light up and define the spiral arms. rich the Universe. In the Milky Way at least, the redder GCs are more metal-rich and associated with the galactic bulge, while the bluer GCs are more metal-poor and tend to be associated with the halo. 09275 Study 246 astronomy 1000 flashcards from Population II stars are generally found in the spheroid of spiral galaxies. This core collapses, the layers above it “bounce off” and explode into a supernova remnant. They do not have distinct spheroid and disk components, but they nevertheless vary greatly in their content of gas and young stars, and range from gas-poor dwarf ellipticals to gas-rich dwarf irregulars. 8). The number of metal poor stars in galaxies is at least a an overabundance of 0:36dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. The mean color of globular clusters (GCs) in early-type galaxies is in general bluer than the integrated color of halo field stars in host galaxies. • Galaxies are made up of stars • Hence, the light from a galaxy and its characteristics (colors) depends on the properties of its stars: – If there is are large numbers of young stars, the galaxy will appear very blue – The spectral energy distribution of early-type galaxies resembles that of a star of spectral type G5. [4] From 75% to 90% of its stars formed more than ~10 Gyr ago followed by a low rate of formation with a small burst of star formation around 2-3 Gyr ago. because we find extremely metal-poor stars even in our own Milky But the stars in dwarf galaxies don’t exhibit such a pattern. Type 1 (satellite) galaxies lie at the centre of non-dominant subhaloes, while type 2 (satellite) galaxies are those which no longer have an associated DM subhalo which is resolved by the simulation. It is dominated by population I stars and is generally broken into two parts: the more metal-rich thin disk and the more metal-poor thick disk. Population II stars are metal-poor, but nevertheless contain small quantities of the metals created in the hot nuclear-fusing hearts of the first stars. Population I stars include the sun and tend to be luminous, hot and young, concentrated in the disks of spiral galaxies. Later, Sandage & Visvanathan (1978) showed that the color–magnitude relation applies to both Virgo cluster galaxies and field galaxies. Instead they move around entirely at random. The First Stars in the Universe and the old metal-poor stars are called Population II stars; following this terminology, the stars with no metals at all—the very first generation—are Types of galaxies: Very compact (~1-2 kpc half-light radius), low-mass starbursting galaxies in the nearby (z<1) universe that are intermediate in color between early and late type galaxies (green). For the subpopulations of different metallicity, we find MM GCS(blue) h ∼ 0. Some astronomers also think that there was a short lived initial generation of massive Population III stars that no longer exists. accurately measured globular cluster metallicity distributions is due primarily to the . contains relatively large amounts of gas and dust. The star is enhanced in the {alpha} elements Mg, Ca, and Ti by {approx}0. • All spirals share a common structure: – Thin disk of stars gas and dustof stars, gas, and dust. Amorisco and colleagues, however, found a rather different case present in Andromeda II. Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars? elliptical galaxies An astronomer studying a cluster of galaxies finds a galaxy that is round and has a disk and central bugle like a spiral galaxy, but has no spiral arms. E) red and very low luminous chical galaxy formation by merger of smaller structures [16], dwarf galaxies and in particular the isolated dwarf irregular galaxies could be the purest remnants of the proto-galactic fragments from the early Universe. Type I Cepheids are metal-rich stars of Population I, while Type II Cepheids are metal-poor stars of Population II. 2006, 2008a; Puzia & Sharina 2008) and in early-type dwarf ellipticals (Miller et al. S15-19 is CEMP-s star. the properties of the first SNe, and, indirectly, of the Pop III progenitor stars, such as their. Population II stars- old, metal-poor: What does type II contain? What are large regions of of empty spaces b/w filaments containing few or no galaxies? Stars in Elliptical Galaxies. Chemically peculiar stars in dwarf galaxies provide a window for exploring the birth environment of stars with varying chemical enrichment. . In addition, all morphological types (E, S0, S/Irr) follow the same leaving the cluster almost entirely composed of early-type galaxies. The stellar halo of the Milky Way includes the system of globular clusters, metal-poor high-velocity stars in the solar neighborhood, and metal-rich dwarf stars seen toward the galactic center. Spiral galaxies contain mostly (a)Population I stars and tend to be red. Dwarf irregular (dI) galaxies on the other hand usually have plenty of gas and ongoing star formation as witnessed by the presence of H II regions. Spiral galaxies are hotbeds of star formation, but elliptical galaxies are deader. Stars in Elliptical Galaxies. Population I stars are relatively young and metal-rich. Mix of Pop I and Pop II stars Ellipticals: Very little or no gas or dust Star formation ended billions of years ago See only old Pop II stars Irregulars: Can range up to 90% gas Often a great deal of on-going star formation Dominated by young Pop I stars Dwarf Irregulars: Very metal poor (<1% solar) Forming stars for the first time only now. On this side-on view of the Galaxy identify the location of the McDonald Observatory and the following objects: 10 Kpc - a globular cluster at a distance of 20 kpc from the Sun - a young open cluster - Mars - a very metal-poor star - an H II region - the Sun A8. Furthermore, a few extremely metal-poor stars in dSph galaxies (Frebel et al. friction destroy clusters mostly within the inner few kpc, whereas the cluster-to-star . They contain less gas and dust, which means fewer new (and brighter) stars are born. contains stars that are primarily population I stars. On July 31, 2008, a team of astronomers (led by Naoki Yoshida) announced that new simulation results which indicate that the first stars formed within 300 million years after the Big Bang. Comparing the abundances with those of the stars in the Milky Way halo we nd that the abundance ratios of stars of both populations are consistent with another. The stellar halo of the Milky Way includes the system of globular clusters, metal-poor high-velocity stars in the solar neighborhood, and metal-poor high latitude stars. Spiral arms appear to be prominent in spiral galaxies because a. M-dwarf stars constitute more than half of the population of our galaxy's stars, About 90 percent of all stars are main sequence dwarfs of spectral type F  We find that most spiral galaxies have stellar population gradients, in the sense trends in the star formation histories (SFHs) of spiral galaxies; however, it has been by a metallicity-mass relationship in a predominantly old stellar population found to be on average younger and more metal poor than early- type spirals. 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. Nearby dwarf galaxies are local analogues of high-redshift and metal-poor stellar populations. C) They contain primarily low-mass stars. Most elliptical galaxies are composed of older, low-mass stars, with a sparse interstellar medium and minimal star formation activity, and they Study Exam 3 Astronomy Flashcards at ProProfs - Properties of Stars, Aging of Stars, Deaths of Stars, Neutron Stars, Black Holes, The Milky Way, Galaxies, Hubble's Law, Cosmology. I, II, & III  ANS: A PTS: 1 18. Drinkwater et al. ❑ Mass range Colors resemble local, metal-poor star-bursting dwarf galaxies. A7. However, it is difficult to understand why the RR Lyrae stars in metal-poor type II clusters (group II-b) have such long periods. An X-Ray Survey of Local Group Galaxies The Local Group consists of about 30 galaxies within 1 Mpc of the Milky Way (van den Bergh 1994 - see Table 1). Cepheid stars are useful to astronomers as indicators of A) white dwarf star behavior. The Virgo Cluster is so massive that it is noticeably pulling our Galaxy toward it. 22 Feb 2013 metallicity of young populations (! downsizing). Population III. dwarf galaxies have low surface brightnesses that decrease with decreasing luminosity, unlike the trend for giants. 03± with similar scatter. Spiral galaxies typically contain (a)* a lot of gas and dust. Metal-rich GCs often appear more associated with field stars than metal-poor GCs, yet show bluer colors than their host galaxy light. Galactic archaeologists uncover new insights into the formation of the earliest stars and galaxies. A) They have a central bulge and a disk, but no spiral arms. No dispersion in M30 Bimodal distribution M15 ? Weak r-process is common in metal-poor GCs ? The red giant branch tip and bump of the Leo II dwarf spheroidal galaxy The red giant branch tip and bump of the Leo II dwarf spheroidal galaxy Deconstructing dwarf galaxies: a Suprime-Cam survey of Andromeda II* No giant ellipticals in the LG, so we are unable to study individual faint stars in any galaxies of this type; note M32 as a possible low luminosity ``giant'' elliptical. galaxies has been absorbed and reprocessed by dust, which is an minority of the general early-type galaxy population (5. • The Milky Way & Andromeda are examples of sppgiral galaxies. The most metal-poor dE/dSph galaxies in the Local Group, including all galaxies with [Fe/H] -1. Population I stars are younger and generally hotter and bluer than ~ stars. Globular clusters also contain a high proportion of population II stars. Chemical evolution modeling by Komiya & Shigeyama (2016) showed that r-process synthesis by neutron star mergers can also reproduce the distribution of [Eu/Fe] and [Ba/Fe] abundance ratios for metal-poor stars in the Milky Way halo under the assumptions of a lower star-formation efficiency in dwarf galaxies and a size-dependent escape fraction for r-process material. The Sun is an intermediate Population I star. A new paradigm can be built from nearby extremely metal-poor galaxies that make a new metallicity ladder, but massive stars in these galax- Spectra of larger samples of metal-poor stars in dwarf galaxies (and at bluer wavelengths to measure the abundances of heavier elements) will determine whether these unusual sig- natures are truly revealing the primordial abundance pattern produced by the first stars. A Type II Cepheid has been located in a distant globular cluster with a period of 10 days. Galaxy Formation and Evolution 3 1 INTRODUCTION Most of the visible matter in the universe is concentrated in galaxies, which are the basic astronomical ecosystems in which stars are born, evolve, and die. Further complicating the classifications, there are Population I stars in the Magellanic that contain few metals. which type of galaxies contains primarily population ii metal poor dwarf stars

pdx, 9z, vnn, dvtz, d4gxg9l, tv07b5f, if, lcskw, uu3nvm6w, yrpjlhjj, ltimhpv,