It is about 25,000 light-years away from the Earth and 42,000 light-years from the center of the Galaxy. Although they used to have a more familiar shape, a dramatic collision with another galaxy has … AU - Hunter, DA. Found insideA comprehensive examination of nearly fourteen billion years of galaxy formation and evolution, from primordial gas to present-day galaxies. Irregular galaxy IC 3583 has been found to have a bar of stars running through its center. Stars might also be classified on the basis of the thickness of the disc, halo, or the bulge of the galaxy. The stars in ellipticals tend to be older. N2 - We present deep UBVJHK H alpha images and H I maps of the irregular galaxy NGC 2366. The Canis Major Dwarf galaxy is an irregular galaxy, and, if it really exists, is probably the closest galaxy to our location in the Milky Way, though not the closest to the center of the Milky Way. Type I's are usually single galaxies of peculiar appearance. Found insideThis Carnegie volume discusses the origin and evolution of elements in our galaxy and others. The Small Magellanic Cloud (SMC), or Nubecula Minor, is a dwarf galaxy near the Milky Way. There are many different example of irregular galaxies. Near- and far-IR data and mm-wave CO observations are used to study the star-forming properties of the Magellanic irregular galaxy NGC 4214 and its interstellar medium. Found inside – Page iiIt is sometimes said that astronomy is the crossroads of physics. In the same spirit, it can forcefully be argued that galaxies are the crossroads of astronomy. in order to expose the halo population of this galaxy. Found insideWho—or what—is out there? In Cosmos, Carl Sagan explained the universe. In Contact, he predicts its future—and our own. We investigate the intermediate-age asymptotic giant branch stellar population of two Local Group dwarf irregular galaxies to characterize their carbon star population in near-infrared (IR). Our Milky Way galaxy is an example of the spiral galaxy. Mid-Infrared Images of Stars and Dust in Irregular Galaxies We present mid-IR to optical properties of 22 representative irregulargalaxies: 18 irregular (Im) galaxies, 3 blue compact dwarfs, and 1Magellanic-type spiral galaxy. 2015). free, stellar halos around low-mass galaxies constrain properties such as star formation in the accreted subhalos and the formation of dwarf galaxies. The central bright region at the core of a galaxy is called the “galactic bulge”. They form the disk of the galaxy. Halo is present. The dI galaxies are rich in gas and actively forming stars, usually located in the field, while dSph galaxies do not present significant star formation activity (Mayer et al. Millions of stars are present in the galaxy and the diameter of galaxy ranges from 1000 light years to one million light years. We present resolved-star VI photometry of the Local Group dwarf irregular galaxy IC1613 reaching I~23.5, obtained with the wide-field camera at the 2.5m Isaac Newton Telescope. Irregular galaxies often appear disorganized, and many are undergoing relatively intense star formation activity. Presents latest research results on star formation and chemical evolution in the context of the early Universe, for researchers. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in ... The enormously powerful phenomena of starbursts are examined in this book. These spectacular star-forming events are seen on large scales in some galaxies, often triggered by galactic interactions. These galaxies have no discernible shape or structure. Bright stars are mostly concentrated toward the galaxy center, and only a few of them are present at large galactocentric distances, in agreement with what was already observed in other dwarf irregular galaxies, (e.g., Tosi et al. The majority of irregular galaxies are very bright, which is a result of the gas and dust in them. Spiral galaxies are the most common type in the universe. Explanation: The reason is because irregular galaxies do not look like regular shaped galaxies like elliptical galaxies and spiral galaxies because all of their stars are shaped in an irregular shape or a shape that has not been seen before by the Hubble Space telescope. Galaxies are composed of stars, dust, and dark matter, all held together by gravity. 2007), producing 13 galaxies, which defines our irregular galaxy sample. Q. Irregular Galaxy – smaller, fainter, spread unevenly Explanation: The reason is because irregular galaxies do not look like regular shaped galaxies like elliptical galaxies and spiral galaxies because all of their stars are shaped in an irregular shape or a shape that has not been seen before by the Hubble Space telescope. Irregular Galaxy – Irregular Galaxies are young galaxies with more gases and dust, this makes them very bright. Figure 12a is an example of the optical spectral energy distribution of an old, gasless stellar population. Answer: Several billion stars that are arranged in a shape that has uneven edges. The galaxy is forming stars at present at about 0.5-1 solar mass/yr in its central few arcmin, if the new stars follow the Salpeter initial mass function from 0.1 to 100 solar masses. Get the latest updates on NASA missions, watch NASA TV live, and learn about our quest to reveal the unknown and benefit all humankind. Y1 - 2001/8/1. Because of all this dust and gas, an irregular galaxy has lots of new star formations going on. These galaxies span a wide range of sizes, from dwarf galaxies containing as few as 100 million stars to giant galaxies with more than a trillion stars. The Large and Small Magellanic Clouds are examples of irregular galaxies. In Section 2, we present the observations, data reduction, and profile-fitting photometry. In addition to the two super-star clusters that are well known, we identify … Distribution of star … The specific star-formation rate (sSFR = SFR/M∗) of radiative-mode AGN hosts compared with normal star-forming galaxies (SFGs) as a function of redshift. They are among the smallest galaxies and are full of gas and dust. Another Dwarf Irregular Galaxy with a Population II Stellar Halo Dante Minniti 1,2, Albert A. Zijlstra 3,4 & M. Victoria Alonso5 ABSTRACT We have obtained V and I-band photometry for about 17500 stars in the field of the dwarf irregular galaxy NGC 3109, located in the outskirts of the Local Group. The present-day solar photospheric elemental abundances as a function of atomic number. Irregular galaxies are particularly underevolved compared to spiral and elliptical galaxies and so they pose an interesting glimpse of the early stages of galaxy evolution. The Local Group is part of the Virgo Supercluster, which contains hundreds of galaxies. Irregular galaxies often appear disorganized, and many are undergoing relatively intense star formation activity. The stars, planets and galaxies only make up 4% of the universe, the 96% cannot be seen or understood. This type of Galaxy can be identified in a very easy way.Such a Galaxy has a disk, a bulge and a halo.Such a galaxy has a nucleus at the center, which is located in the center as a bulge in the shape of a solid round ball.Where many stars, clouds of dust and gas are present.In the arms of such galaxies that are away from the center, new wires are formed there. (There are quite a few dwarf galaxies nearby.) No regular shape. The central bar of the galaxy contains the oldest stars and no star … Universe –everything that exists, 10 billion-20 billion years old. Sometimes they get lumped in with the so-called "peculiar" galaxies due to their unusual shapes or other characteristics. stars in the tidal tail region which were formed later than most stars in the main body of the galaxy. Spiral Galaxies ... •Gas and dust rotate around the central hub of the galaxy •Both young and old stars are present Found inside – Page 253IRAS Observations of Irregular Galaxies D. Hunter Dept. of Terrestrial ... We present preliminary results from an investigation of the dust content of ... Irr I galaxies are similar to spirals because they have lots of gas and young stars. This gas and dust means that many stars are formed within an irregular galaxy, giving them their brightness. The most massive can contain nearly a trillion stars, or about a thousand times more than the Milky Way. In § 5 we present models for two irregular galaxies, NGC 1560 and II Zw 33, for which the amount of nonbaryonic dark matter is known. Q. Ursa Major is also called “Great Bear” and is one of the largest constellations. Astronomers classify galaxies into three major categories: elliptical, spiral and irregular. The stars in elliptical galaxies are old Population II stars. We examine star clusters in the irregular starburst galaxy NGC 1569 from Hubble Space Telescope images taken with filters F336W, F555W, and F814W. Bright stars are mostly concentrated toward the galaxy center, and only a few of them are present at large galactocentric distances, in agreement with what was already observed in other dwarf irregular galaxies, (e.g., Tosi et al. 1. In fact, there are two types of irregular galaxy. This book contains the proceedings of the second conference. It is suitable for researchers and PhD students in Astrophysics. The young stars are formed in the outer arms of the galaxy while the old stars are formed in the inner arms. Galaxies are made up of interstellar gas, dust and loads of stars and dark matter all bound together by a gravitational bond. In Hubble’s scheme, which is based on the optical appearance of galaxy images on photographic plates, galaxies are divided into three general classes: ellipticals, spirals, and irregulars. The book begins with relevant scientific fundamentals and progresses through an exploration of the solar system, stars, galaxies, and cosmology. The universe has more than 1000 solar system that has not been even discovered by humans. Did You Know…the Milky Way contains around 400 billion stars and possbily that many planets? A galaxy is a gravitational bond between different stars, gases, dust, and dark matter. These units are woven together to flow naturally for the person who wants to read the text like a book, but it is also possible to assign them in different orders, or skip certain units altogether. Do irregular galaxies have gas and dust? Irregular galaxies are those galaxies, which look neither Elliptical nor Spiral and have no true shape or form. Hubble classified galaxies that do not have the regular shapes associated with the categories we just described into the catchall bin of an irregular galaxy, and we continue to use his term. We have to use clever tricks to study it. Here we present gi photometry of resolved stars in isolated Local Group dwarf irregular galaxy IC 1613 (Må ∼ 108 Me). This volume provides very up-to-date material on the subject of the interstellar medium in galaxies and is useful both as a basic reference for professional scientists in this field and as an introductory book for astronomers who want to ... There are three major types of irregular galaxies:An Irr-I galaxy ( Irr I) is an irregular galaxy that features some structure but not enough to place it cleanly into the Hubble sequence. ...An Irr-II galaxy ( Irr II) is an irregular galaxy that does not appear to feature any structure that can place it into the Hubble sequence.A dI-galaxy (or dIrr) is a dwarf irregular galaxy. ... The Elliptical Galaxy […] And there are also galaxies that aren’t spirals or ovals. RR Lyrae and short-period variable stars in the dwarf irregular galaxy NGC 68221 Gisella Clementini,2 Enrico V. Held,3 Lara Baldacci,2,4 Luca Rizzi3,5 ABSTRACT arXiv:astro-ph/0304076v1 3 Apr 2003 We report the discovery of a large number of short-period variable stars in the dwarf irregular galaxy NGC 6822, based on deep time-series imaging carried out with the ESO Very Large Telescope. 2001; Gallart et al. https://www.le.ac.uk/ph/faulkes/web/galaxies/r_ga_irregular.html In this chapter, the idea of star formation in spiral galaxies is addressed. In addition to the two super star clusters that are well known, we identify 45 other clusters that are compact but resolved. The closest galaxy to the Milky Way happens to be an irregular galaxy called the Canis Major Dwarf. Irregular galaxies are particularly underevolved compared to spiral and elliptical galaxies and so they pose an interesting glimpse of the early stages of galaxy evolution. T1 - Neutral hydrogen and star formation in the irregular galaxy NGC 2366. This book succeeds in making the immense and remote universe of galaxies much more accessible to our imagination. It also conveys the excitement and wonder of this rapidly changing area of scientific inquiry. Synonyms for irregular galaxy include galaxy, nebula, cluster, constellation, heavens, stars, spiral galaxy, star system, trichiliocosm and Seyfert galaxy. The IRAS survey showed that far-IR emission is ubiquitous among spiral and irregular galaxies, even some for which optical data suggested a very modest dust content. NASA.gov brings you the latest images, videos and news from America's space agency. Irregular galaxies often appear disorganized, and many are undergoing relatively intense star formation activity. Irregular galaxies have no particular shape. A fit to the stellar density distribution shows an exponential profile of scale length 2.9' ± 0.1' and gives a central surface brightness μ V,0 = 22.7 ± 0.6. For stars like the Sun, the mass-to-light ratio is 1 by our definition. Galaxies are not, of course, composed entirely of stars … Studying our own galaxy is difficult since we can't get outside of it and look back. The Irregular Galaxy. AU - van Woerden, H. PY - 2001/8/1. They contain both young population I stars and old population II stars. Irregulars make up a smaller percentage of all galaxies, estimated to be about 25%; they were probably more prevalent in the early Universe. Answer: Several billion stars that are arranged in a shape that has uneven edges. An irregular galaxy is the catchall name given to any galaxy that does not neatly fit into one of the categories of the Hubble classification scheme. Irregular galaxies are often chaotic in shape, with no central bulge or spiral arms. This second edition has been updated and substantially expanded. So this is a grand tour indeed, encompassing the birth of the universe with the Big Bang, hypotheses on its eventual demise, and fascinating conjectures about its shape and possible alternate "mulitiverses. Found insideThis second edition includes substantial new material throughout, including the latest findings from the New Horizons, Rosetta, and Dawn space missions, and images from professional telescopes such as the Hubble Space Telescope and the ... Galaxy Spectra. They don’t seem to fit into either the spiral or elliptical galaxy categories. The list of galaxies was then cross referenced to determine the inclusion in SDSS DR5 (Adleman-McCarthy et al. Irregular galaxies comprise both old and young stars, substantial volumes of dust and gas, and generally displaying bright bulges of star formation. This comprehensive volume reviews our current knowledge of the origin and evolution of elements, from stellar nucleosynthesis to the chemical evolution of the cosmos. Long [gamma]-ray bursts (GRBs) are uniquely powerful explosions at cosmological distances. Found inside – Page 35This galaxy is classified as a clumpy irregular galaxy (ClG) according to its morphological properties (cf. ... The response of gas clouds are also investigated in order to estimate star formation rates in such collisions. ... (1988) and Noguchi and lshibashi (1986). ln the present model, an intruding galaxy with the same mass of a target galaxy moves on a rectilinear orbit which passes the center of the target. The Andromeda Galaxy is the nearest spiral galaxy to our Milky Way, but not the closest galaxy. Typically, irregular galaxies have lower masses and luminosities than spiral galaxies. Found inside – Page 53( Author ) A91-10687 Supernova - driven wind models and the early evolution of sphoroidal star systems . L. Angeletti and P. ... 99-105 . 38 refs . A detailed analysis of the characteristics of the dwarf irregular galaxy IC 4662 is presented . However, few observational searches for stellar halos in dwarfs exist. Near the poles, the stars appear to rotate in a circle in the sky and never set. Some irregular galaxies clearly look like two galaxies ran into each other! Many characteristics of the gas and stars are consistent with a picture in which NGC 4449 has been disturbed by an external perturber, and the gas has not yet returned to equilibrium. INTRODUCTION UGC 7636 (VCC 1249) is a dwarf irregular galaxy (Im III-IV: Binggeli et al. Found inside – Page 116Individual star-forming regions in BCDs are relatively large, giving the galaxies a clumpy, irregular appearance in Hα (Kunth et al. 1988; Cairós et al. ). This book will show what is out there in the universe, what it’s like in other galaxies, what they might look like, and how cosmic processes might affect life in other solar systems. Found inside – Page 33Supernova Rate The estimated age of M 82 since the burst of star formation ranges from 5 to 18 x 10 ? yr , according to the ... One important aspect of this problem is the number of supernova remnants produced by the massive stars present in ... The plan of the paper is as follows. Galaxies and the Universe. They have neither noticeable symmetry nor an obvious central nucleus, and they are generally bluer in colour than are the arms and disks of spiral galaxies. Spiral Galaxy. Usually rich in gas and dust. The specific star-formation rate (sSFR = SFR/M∗) of radiative-mode AGN hosts compared with normal star-forming galaxies (SFGs) as a function of redshift. galaxy - galaxy - Irregular galaxies: Most representatives of this class consist of grainy, highly irregular assemblages of luminous areas. In this paper, we present and analyze the results of a search for Cepheid stars in the dwarf irregular galaxy of Pegasus, using data spanning 11 years. These stars are present in elliptical galaxies, and they form very early in the galaxy's history of star formation. A coherent introduction for researchers in astronomy, particle physics, and cosmology on the formation and evolution of galaxies. Galaxies and Constellation. Structure and Evolution of Irregular Galaxies. 4.Young and old stars are present. The present-day solar photospheric elemental abundances as a function of atomic number. 1.NO predictable shape 2.MAY have bulge and /or disk 3.USUALLY rich in gas and dust 4.Young and old stars are present. Spiral galaxy is the Galaxy that was formed in a spiral shape with a distinct flattened disk-like structure with a bright center called a nucleus. Example of Irregular Galaxy is Magellanic Cloud. A galaxy contains trillions of stars within it. In general, irregular galaxies contain large amounts of gas and dust, and can exhibit a significant degree of star formation activity. The masters of stellar population synthesis code (building a galaxy from individual stars) are Bruzual & Charlot.The Kennicutt atlas of optical galaxy spectra of various types can be found here.A popular set of UV galaxy templates are those of Coleman, Wu & Weedman.Here is a short introduction to the stellar populations found within typical galaxy spectra. NGC 2337 is an irregular galaxy that resides 25 million light-years away in the constellation of Lynx. We present deep Hubble Space Telescope (HST) single-star photometry of Leo A in B, V, and I. It could contain up to one billion stars, with an unusually high proportion of red stars. Found inside – Page 1This book reviews the history behind the discovery of spiral galaxies and the problems faced when trying to explain the existence of spiral structure within them. However, few observational searches for stellar halos in dwarfs exist. Its membership of Having a lot of gas and dust means that these galaxies have a lot of star formation going on within them. They come in a variety of shapes, sizes, and ages. They’re called elliptical galaxies. All galaxies fainter than M ~ -18 (in the V band) situated beyond the nominal virial radius of the Milky Way and M31 (> 300 kpc) are included in this volume-limited sample, for a total of 42 targets. Traditionally, dwarf galaxies are classified in two main categories, the dwarf Irregular (dI) and the dwarf Spheroidal (dSph). Irregular galaxies will have stars mostly clustered inside nebulous areas. Found inside – Page 1This book is intended to be a course about the creation and evolution of the universe at large, including the basic macroscopic building blocks (galaxies) and the overall large-scale structure. 1985) located 50:5 southeast of the center of the giant elliptical galaxy NGC 4472 (M49), the brightest galaxy in … Stars, Galaxies, and the Universe Section Summary These odd, blobby ones are called "irregular" galaxies. They have irregular shapes and look like blobs. galaxy are billions of other galaxies, many which contain billions of stars. faint variable stars in the isolated dwarf irregular galaxy ic 1613 A galaxy is a huge assembly of stars, dust and gases, mutually held together by gravitational force . There are, however, two general types of irregulars. Galaxies range from 1,000 to 100,000 parsecs in diameter and are usually separated by millions of parsecs. Readers are introduced to the large-scale shock scenario, which … ii. Describe Quasars. Find 6 ways to say IRREGULAR GALAXY, along with antonyms, related words, and example sentences at Thesaurus.com, the world's most trusted free thesaurus. Barred spiral - This type of galaxy is similar to the spiral but has a long bar in the middle with spirals coming off the ends. galaxy. Basing his theory on the observation of the change in distanct galaxies, called red shift, Hubble showed that this is a Doppler effect, or alteration in the wavelength of light, resulting from the rapid motion of celestial objects away from ... Q. Around 20% of all galaxies are irregular. An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. May show signs of a disk and/or bulge. Here we present gi photometry of resolved stars in isolated Local Group dwarf irregular galaxy IC 1613 (M-* similar to 10(8) M-circle dot). This means they are full of gas and dust and usually very small with no particular shape. The significant number of red giant branch (RGB) stars present … The galaxy is more than 13.5 billion years old and consists of our solar system in which the earth is present. They don’t have nice spiral arms, but they do have dark patches of gas and dust. Found insideFundamentals of Galaxy Dynamics, Formation and Evolution is written for advanced undergraduates and beginning postgraduate students, providing a useful tool to get up to speed in a starting research career. Irregular Galaxies. This class includes any galaxy which cannot be classified as either spiral or elliptical. Find more similar words at wordhippo.com! Irregular galaxies have no identifiable shape or structure to them. Other galaxies are smooth and oval shaped. Irregular; Spiral Galaxy. Astronomers have discovered there are four main types of galaxies; the elliptical, spiral, lenticular and irregular. ... Technology found six star forming galaxies about 13.2 billion light ... Galaxies) is an example of a present merger. Some irregular galaxies were once spiral or elliptical galaxies but were deformed by an uneven external gravitational force. Irregular galaxies may contain abundant amounts of gas and dust. This is not necessarily true for dwarf irregulars. Irregular galaxies are commonly small, about one tenth the mass of the Milky Way galaxy. Edwin Hubble invented a classification of g… This can make them very bright. Many spirals have a halo of stars and star clusters arrayed above and below the disk. AU - Elmegreen, BG. Irregular Galaxy. This type of population is typical of the bulge and old disk populations in galaxies. Mid-Infrared Images of Stars and Dust in Irregular Galaxies We present mid-IR to optical properties of 22 representative irregulargalaxies: 18 irregular (Im) galaxies, 3 blue compact dwarfs, and 1Magellanic-type spiral galaxy. This volume deals with the most recent theories of violent star formation. There can be anywhere from 10 million to 100 trillion stars in one galaxy! It is the largest galaxy in the "Local Group" of 50 galaxies with about a trillion stars. Found inside – Page 156FOUR YEARS OF IUE RESEARCH ON CLUMPY IRREGULAR GALAXIES P. Benvenuti C. Casini J. Heidmann ESA IUE ... B type stars are present with indication of supergiant stars . iii ) the continuum could be accounted for by the radiation of ... It is an immense cosmic dance, choreographed by gravity. Cosmic Collisions contains a hundred new, many thus far unpublished, images of colliding galaxies from the NASA/ESA Hubble Space Telescope. Also, in some irregular galaxies, like M82, young stars eject energetic bubbles gas, giving the galaxy a blobby look. As their name suggests, elliptical galaxies are round or oval, with stars distributed fairly uniformly throughout. Sometimes the faint remnants of spiral arms can be seen. Thus in some sense every irregular galaxy is unique in it's appearance. In particular the affect that certain models of spiral structure have on the location of star formation in spiral galaxies is discussed. This books looks at 60 of those that possess some unusual qualities that make them of particular interest, from supermassive black holes and colliding galaxies to powerful radio sources. Population I stars are younger and more metal rich. Irregular galaxies are divided into two classes, Im and IO. The light that we see from each of these galaxies comes from the stars inside it. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): We examine star clusters in the irregular, starburst galaxy NGC 1569 from HST images taken with filters F336W, F555W, and F814W. The Milky Way is the second largest galaxy with roughly 300 billion stars. In the center of the spiral galaxy are older stars while the arms are generally made of new stars. Irregular galaxies are appropriately named. AB - We present high-resolution interferometric data of the inner 30' of the H I gas of the irregular galaxy NGC 4449. The closest galaxy to the Milky Way happens to be an irregular galaxy called the Canis Major Dwarf. Structure and Evolution of Irregular Galaxies. Open clusters are not seen in elliptical galaxies: star formation ceased many millions of years ago in ellipticals, and so the open clusters which were originally present have long since dispersed. Elliptical - A mass of stars clumped together in the shape of an elliptical disc. Galaxy Type . There's another set of galaxies that are rather shapeless, don't necessarily have spiral arms, but do have a lot of sites where stars are forming. In irregular galaxies, open clusters may be found throughout the galaxy, although their concentration is highest where the gas density is highest. We report the detection of metal-poor red horizontal branch stars, which demonstrate that Leo A is not a young galaxy. We present resolved-star VI photometry of the Local Group dwarf irregular galaxy IC 1613 reaching I ~ 23.5, obtained with the wide-field camera at the 2.5 m Isaac Newton Telescope. After galaxies form, they evolve primarily by mergers and interactions. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Received xxx; accepted xxx Aims. Describe Elliptical Galaxy. A concise and up-to-date guide to the shape of galaxies and how they can be classified, by one of the pioneers of the field. Population I stars are newer, more luminous, and hotter than Population II stars. SDSS DR5 g ' images of these galaxies are shown in Figures 1 – 3 . Another Dwarf Irregular Galaxy with a Population II Stellar Halo Dante Minniti 1,2, Albert A. Zijlstra 3,4 & M. Victoria Alonso5 ABSTRACT We have obtained V and I-band photometry for about 17500 stars in the field of the dwarf irregular galaxy NGC 3109, located in the outskirts of the Local Group. The mid-IR is based on images from theSpitzer Space Telescope archives. Irregular Galaxy - A fourth type of galaxy is known as the irregular galaxy. Our Milky Way is a spiral, as is the rather close-by Andromeda Galaxy. We investigate how the cosmic environment affects galaxy evolution in the Universe by studying gas-phase chemical abundances and other galaxy properties as a function of the large-scale environment and local density of galaxies. The two best-known irregular galaxies are the Large Magellanic Cloud and Small Magellanic Cloud ( Figure 26.9 ), which are at a distance of a little more than 160,000 light-years away and are among our nearest extragalactic … Describe Irregular Galaxy. Smecker-Hane, Tammy A. At least half of all galaxies in the Universe are thought to belong to similar groups. This authoritative volume provides a comprehensive synthesis of what is known about the Local Group. They contain both young population I stars and old population II stars. The present study investigates a novel method for studying the star formation histories of nearby irregular galaxies. With just one billion stars, it appears to be a small galaxy in the process of being consumed by our own galaxy. galaxy - galaxy - Types of galaxies: Almost all current systems of galaxy classification are outgrowths of the initial scheme proposed by the American astronomer Edwin Hubble in 1926.