Download or read book A Comprehensive Study of Star Formation in Blue Compact Dwarf Galaxies written by Ramya Sethuram and published by LAP Lambert Academic Publishing. This book was released on 2012-02 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an observational project on Blue Compact Dwarf Galaxies (BCDG). The book gives an insight into the star formation and star formation history of BCDGs. The data of galaxies deals with optical photometry, medium resolution spectroscopy of nearly 11 galaxies. The data of 5 galaxies from this sample are studied in low frequency radio continuum bands and neutral hydrogen gas is also mapped in these systems. The book forms a guide to understand the broad band and narrow band photometric techniques. A detailed photometric and spectroscopic catalogue of 11 nearby BCDGs is composed. An account of mixed population model, created using Starburst99, that reveals at least three different kinds of population [ 10 Myr, 500 Myr and 4-5 Gyr] existing in these regions is given. A detailed calculation of the amount of metals present in the ionized gas using empirical relations is presented in the book. The intriguing inferences from low frequency radio data are discussed. This book overall forms a guide to observe, infer and understand SF & SFHs of BCDGs using integrated optical & radio light.
Download or read book Star forming Dwarf Galaxies and Related Objects written by D. Kunth and published by Atlantica Séguier Frontières. This book was released on 1985 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On Formation and Evolution of the Blue Compact Dwarf Galaxies and on Star Formation Region Properties written by Yu. I. Izotov and published by . This book was released on 1989 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Mid infrared Study of Blue Compact Dwarf Galaxies written by Yanling Wu and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blue Compact Dwarf Galaxies (BCDs) are characterized by their blue optical colors, low luminosities and small sizes. Typically BCDs are found to have low, subsolar metallicities, and they are proposed to be local analogs to the primeval galaxies in the early universe. The unprecedented sensitivity of the Spitzer Space Telescope has enabled, for the first time, the detection of a large sample of these low luminosity systems. In this dissertation, I will present my work employing Spitzer data to study the dust properties and chemical evolution of blue compact dwarf galaxies. Using Spitzer/IRS low-resolution spectra ([lambda]/[delta][lambda] ~ 100), I investigated the presence/absence of the Polycyclic Aromatic Hydrocarbon (PAH) features in lowmetallicity galaxies. After exploring different physical parameters, I find that the strength of PAH emission is best correlated with a combination of formation and destruction effects. In addition, using the high-resolution spectroscopy ([lambda]/[delta][lambda] ~ 600), I study the elemental abundances of neon and sulfur in BCDs and compare with the optical studies. I find that the infrared derived elemental abundances generally agree with the optical results, though the neon abundances are slightly higher from our study. I also analyze the FIR/radio correlation in BCDs and expand the discussion to the mid-IR. I find that the infrared luminosities are well correlated with the radio luminosities even in these low luminosity systems. A study on the spectral energy distribution (SED) and star formation rates (SFRs) in low-luminosity star-forming galaxies is also included in this thesis. The SEDs appear to be warmer than normal star-forming galaxies, and their SFRs vary over an order of magnitude. Finally, I also present a case study on the famous BCD IZw18, showing the first mid-infrared spectrum for this galaxy.
Download or read book A Study of the Neutral Hydrogen Content of Blue Compact Dwarf Galaxies written by Jeremy A MacHattie and published by . This book was released on 2013 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a study of the neutral hydrogen (HI) content and distribution within a sample of 18 blue compact dwarf galaxies (BCDs) are presented. An investigation of the behaviour of the gas-to-dust ratio (GDR) as a function of metallicity (Z) is also presented. Observations of these BCDs was performed using the Very Large Array (VLA) in 2009, a year in which the array was undergoing a technological upgrade to the the Karl G. Jansky VLA (JVLA). The observations were reduced and images processed using the Astronomical Image Processing Software (AIPS), and data cubes for each galaxy were produced. The results include detections of eleven HI lines (two new detections) and ten background continuum sources (two new discoveries). All detections are at a higher resolution and/or sensitivity than previous measurements. These detections spanned a large range of line widths and HI masses; some masses comparable to those in normal galaxies. Of particular interest was the discovery of a compact absorption feature in the dwarf galaxy Haro 11. A paper submitted to the Monthly Notices of the Royal Astronomical Society (MNRAS) Letters on this discovery is presented. Another significant result was the discovery of a highly extended and massive HI region in the dwarf galaxy CGCG 297-017. For those galaxies with no detected HI line or radio continuum, an upper limit to the flux density was computed, which was used to derive upper limits to the HI mass or star-formation rate (SFR) respectively. Three HI flux density upper limits are new results, and seven continuum flux density upper limits are also new. The GDR-Z relation at low metallicities shows a potential power law or broken power law relation with a turning point at Z=7.96 or Z=8.05. To within error, these turning points and power law indices of the broken power law fits are consistent with other work.
Download or read book NGC 1705 and the Evolution of Blue Compact Dwarf Galaxies written by Hans-Gerhardt R. Meurer and published by . This book was released on 1989 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Galaxies in the Local Volume written by Bärbel Silvia Koribalski and published by Springer Science & Business Media. This book was released on 2009-04-29 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: This timely book presents an overview of the galaxies within the Local Volume, including the Local Group and our closest neighbours, the Andromeda Galaxy and the Magellanic Clouds. Presented here are the latest results from radio, infrared and optical surveys as well as detailed multi-wavelength studies of individual galaxies. The book aims to provide a vibrant forum for presentations and discussions across a broad range of astrophysical topics.
Download or read book The Formation of Stars written by Steven W. Stahler and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 865 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text for physics and astronomy graduate students, and as a reference for professional scientists.
Download or read book The Most Interesting Galaxies in the Universe written by Joel L Schiff and published by Morgan & Claypool Publishers. This book was released on 2018-09-13 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prior to the 1920s it was generally thought, with a few exceptions, that our galaxy, the Milky Way, was the entire Universe. Based on the work of Henrietta Leavitt with Cepheid variables, astronomer Edwin Hubble was able to determine that the Andromeda Galaxy and others had to lie outside our own. Moreover, based on the work of Vesto Slipher, involving the redshifts of these galaxies, Hubble was able to determine that the Universe was not static, as had been previously thought, but expanding. The number of galaxies has also been expanding, with estimates varying from 100 billion to 2 trillion. While every galaxy in the Universe is interesting just by its very fact of being, the author has selected 51 of those that possess some unusual qualities that make them of some particular interest. These galaxies have complex evolutionary histories, with some having supermassive black holes at their core, others are powerful radio sources, a very few are relatively nearby and even visible to the naked eye, whereas the light from one recent discovery has been travelling for the past 13.4 billion years to show us its infancy, and from a time when the Universe was in its infancy. And in spite of the vastness of the Universe, some galaxies are colliding with others, embraced in a graceful gravitational dance. Indeed, as the Andromeda Galaxy is heading towards us, a similar fate awaits our Milky Way. When looking at a modern image of a galaxy, one is in awe at the shear wondrous nature of such a magnificent creation, with its boundless secrets that it is keeping from us, its endless possibilities for harboring alien civilizations, and we remain left with the ultimate knowledge that we are connected to its glory.
Download or read book On the Prevalence of Starbursts in Dwarf Galaxies written by Janice Christine Lee and published by . This book was released on 2006 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: An outstanding question in galaxy evolution research is whether the star formation histories of low mass systems are dominated by global starbursts or modes that are more quiescent and continuous. In this thesis, we quantify the prevalence of global starbursts in dwarf galaxies at the present epoch, and attempt to infer their characteristic durations, frequencies and amplitudes in the past. Our approach is to directly tally the number of bursting dwarfs in a complete local sample, and to compute the fraction of star formation that is concentrated in these systems. The resulting starburst number and mass fractions are then combined with B-V colors from the literature, the H-alpha EWs presented here, and stellar evolutionary synthesis models in order to place constraints on the average starburst duty cycle. The primary dataset used has been put together by the 11 Mpc H-alpha UV Galaxy Survey, who have collected data on an approximately volume-limited, statistical sample of star-forming galaxies within 11 Mpc of the Milky Way. Our main observational results, along with the accumulation of star formation studies of dwarf galaxies over the past three decades, paint a consistent picture where systems that are currently experiencing a massive global burst are just the 6% +/- 3% tip of a low-mass galaxy iceberg. Moreover, bursts are responsible for 22% +/- 10% of the total star formation in the overall dwarf galaxy population, so the majority of stars in low-mass systems do not appear to be formed in this mode today. Over their lifetimes, however, a greater fraction of the stellar mass of a dwarf may be formed in the burst mode. Synthesis modeling suggests that bursts cycles appear to be necessary in order to simultaneously explain the present-day observed blue B-V colors and modest H-alpha EWs of TYPICAL, CURRENTLY NON-BURSTING dwarf irregulars, unlessnon-standard assumptions concerning the IMF and the escape fractions of Lyman continuum photons are made. The starburst cycle that we converge upon involves burst durations of 50-100 Myrs, cycle frequencies of 1 to 3 per Gyr, and elevated burst SFRs that are a factor of 6-10 higher than the rate in the quiescent state. Galaxies characterized by such a SFH would spend 1̃0% of their lives in the burst state, and form 5̃0% of their stellar mass during this time.
Download or read book Star Formation in Dwarf Irregular Galaxies written by Robbie Christopher Dohm-Palmer and published by . This book was released on 1998 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomical Data Analysis Software and Systems XVI written by Richard A. Shaw and published by . This book was released on 2007 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring Star Formation in Dwarf Galaxies at Z1 written by Riona Ramraj and published by . This book was released on 2014 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book FORMATION AND EVOLUTION OF BLUE COMPACT DWARF GALAXIES written by Luz Marina Cairós Barreto and published by . This book was released on 2001 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Outskirts of Galaxy Clusters IAU C195 written by International Astronomical Union. Colloquium and published by Cambridge University Press. This book was released on 2004-12-16 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the International Astronomical Union Colloquium no. 195, held in Torino, Italy in 2004. The meeting investigated the formation of galaxies within a full cosmological context, focusing on the outer regions of galaxy clusters. The observed correlation of optical and radio properties of galaxies with their environment indicates that the formation and evolution of galaxies is intimately linked to the formation of large scale structure. With chapters written by leading authorities in the field, this timely volume investigates the role of the environment in determining the properties of galaxies. It describes the distribution of matter and galaxies on the largest scales in the Universe, the processes of cluster and galaxy formation, their role and interplay. This is a valuable collection of review articles for professional astronomers.
Download or read book Dwarf Galaxies Keys to Galaxy Formation and Evolution written by Polychronis Papaderos and published by Springer Science & Business Media. This book was released on 2012-04-23 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dwarf galaxy research constitutes an extremely vibrant field of astrophysical research, with many long-standing questions still unsettled and new ones constantly arising. The intriguing diversity of the dwarf galaxy population, observed with advanced ground-based and space-borne observatories over a wide spectral window providing an unprecedented level of detail, poses new challenges for both observers and theoreticians. The aim of this symposium was to bring together these two groups to exchange ideas and new results on the many evolutionary aspects of and open issues concerning dwarf galaxies. The main topics addressed include: the birth of dwarf galaxies: theoretical concepts and observable relics across wavelengths and time, the morphological, structural and chemical evolution of dwarf galaxies, possible evolutionary connections between early-type and late-type dwarfs, the star formation history of dwarf galaxies and its dependence on intrinsic and environmental properties, the origin and implications of starburst activity in dwarf galaxies, the fate of dwarfish systems born out of tidally ejected matter in galaxy collisions.
Download or read book Star Formation Histories of Dwarf Galaxies written by John S. Gallagher and published by . This book was released on 1996 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
