- •Государственное образовательное учреждение высшего профессионального образования «Сибирский государственный аэрокосмический университет
- •Preface
- •Credits
- •Table of contents
- •Unit 1 what is science?
- •Part 1: principles of effective reading
- •Skimming: for getting the gist of something
- •Detailed reading: for extracting information accurately
- •Text a the discovery of X-rays
- •Text b call for tolerance towards some 'stem cell tourism'
- •Text c general guidelines
- •Part 2: oral or written?
- •Group 1
- •The academic audience
- •Levels of formality
- •The range of formality Technical → Formal → Informal → Colloquial
- •Part 3: what is science?
- •What is science?
- •Part 4: technology: pros & cons
- •Part 5:listening for academic purposes
- •The Computer Jungle
- •Unit 2 science to life: between the lines
- •Part 1: how effectively can you read?
- •Reading skills for academic study
- •Using the title
- •Part 2: paragraph development and topic sentences
- •Text a Science and Technology
- •Text c Research: Fundamental and Applied, and the Public
- •Part 3: scientists' brain drain Task 16. You are going to read a magazine article (Text a). Choose the most suitable heading from the list (1 – 9) for each part (a – j) of an article
- •Text a highlights of the north
- •Text b bio tech brain drain: are too many talented scientists leaving the southeast?
- •Part 4 reading skills for success
- •Reading skills for success: a guide to academic texts
- •Collocations
- •Part 5: listening for academic purposes
- •Going Digital: The Future of College Textbooks?
- •Part 6: grammar review sentence structure
- •1. Simple sentence:
- •2. Compound sentence:
- •3. Complex sentence:
- •Unit 3 order of importance
- •Part 1 academic vocabulary
- •C a social occasion to which people are invited in order to eat, drink and enjoy themselves
- •A a way of dealing with a problem, an answer
- •Part 2 Coherence
- •The importance of stupidity in scientific research
- •Consumerism is 'eating the future'
- •Now fly me to the asteroids as well
- •Cohesion: Using Repetition and Reference Words to Emphasize Key Ideas in Your Writing
- •Repetition of Key Words
- •Rotation may solve cosmic mystery
- •Part 3 writing & speaking fundamentals
- •Article 1 shapefile technical description
- •Article 2
- •Article 3
- •Article 4 disposable containers for a disposable society
- •Article 5 knowledge, theory, and classification
- •The table of the useful vocabulary
- •Part 4: listening for academic purposes
- •Part 5:grammar review (punctuation)
- •Unit 4 matter of perspectives
- •Part 1 mistakes and negligence
- •Text a mistakes and negligence
- •(1) Changing Knowledge
- •(2) Discovering an Error
- •Part 2 Comparison and Contrast
- •Part 3 listening for academic purposes
- •Recognising lecture structure
- •1. Introducing
- •Unit 5 research misconduct
- •A Breach of Trust
- •Task 4. Study the second case.
- •Treatment of Misconduct by a Journal
- •Part 2 reading skills for academic study: note-taking
- •How to take notes
- •Part 3 preparing an abstract
- •Abstract 1 The hydrodynamics of dolphin drafting
- •Abstract 2 Recomputing Coverage Information to Assist Regression Testing
- •Abstract 3 Methods for determining best multispectral bands using hyper spectral data
- •Abstracts and introductions compared
- •Introduction
- •Introduction
- •Text a The Biosphere: Its Definition, Evolution and Possible Future
- •Introduction
- •Text b The Environment: Problems and Solution
- •Text d The Biosphere: Natural, Man-Disturbed and Man-Initiated Cycles
- •Part 4 listening for academic purposes Giving background information
- •Showing importance/Emphasising
- •Unit 6 finding meaning in literature
- •The Selection of Data
- •Lexical & grammar review
- •Part 2 avoiding plagiarism
- •3. Plagiarism!
- •4. Plagiarism is bad!!
- •5. The importance of recognizing the plagiarism
- •Is It Plagiarism?
- •Part 3 evaluating sources
- •Sample mla Annotation
- •Sample apa Annotation
- •Task 22. Analyse an extract of the following annotated bibliography. Define its format.
- •Ethics in the physical sciences course outline and reference books
- •Philosophy
- •The life of a scientist
- •Ethics for scientists
- •A few cautionary notes on saving Web materials
- •Unit 7 writing & publishing Objectives
- •Part 1 sharing of research results
- •The Race to Publish
- •Part 2 how to read an academic article
- •Article 1
- •50 Million chemicals and counting
- •Article 2 sun is setting on incandescent era
- •How to read a scientific article
- •Part 3 how to write an academic article
- •Publication Practices
- •Restrictions on Peer Review and the Flow of Scientific Information
- •Guidelines for Writing a Scientific Article
- •Part 4 listening for academic purposes
Rotation may solve cosmic mystery
Researchers propose a new explanation for why some tiny galaxies have more than their fair share of dark matter
By Ron Cowen
Web edition : Friday, July 24th, 2009
Dark galaxy
This false-color image shows stars in the dwarf spheroidal galaxy Leo II, just 760,000 light-years from the Milky Way galaxy. The dwarf contains only one-twenty-thousandth the amount of visible material in the Milky Way.
Literally cloaked in darkness, the faintest galaxies in the universe have remained a mystery since their discovery more than two decades ago. Now a team of theorists has come up with a new explanation for the origin of these dim bodies. Known as dwarf spheroidal galaxies, these ancient stellar groupings not only serve as fossil remains of the early universe but have the highest known ratio of dark matter to ordinary, visible matter.
In the most widely accepted model of galaxy formation, an exotic type of invisible material, known as cold dark matter, provides the gravitational glue that draws together stars and gas and keeps galaxies, along with galaxy clusters, from flying apart. It would seem that all galaxies ought to have about the same ratio of dark matter to visible matter, because gravity builds all galaxies in the same way. Yet dwarf spheroidals are the most dark matter–dominated galaxies known, with 10 to 30 times the ratio of dark to visible matter as large galaxies including the Milky Way.
That’s the puzzle that Elena D’Onghia of the University of Zurich and the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and her colleagues set out to solve in a study posted online July 16 (http://arxiv.org/abs/0907.2442) and in an upcoming Nature.
Like other researchers, she and her collaborators assume that dwarf spheroidals were born with a lower, more typical ratio of dark to visible matter, but that much of the visible stuff somehow got pulled out.
Previous models suggest a complex, two-step process to explain the high ratio. But these models require a dwarf spheroidal to lie close to a galaxy as large as the Milky Way. In reality, some spheroidals lie far from such galaxies. Also, these models don’t easily explain the spherical shape of these galaxies or the diversity of their dark matter ratios.
In contrast, the new model proposed by D’Onghia’s team relies on the assumption that stars and gas rotate in fledgling galaxies, a property which the underlying dark matter model of formation requires.
If the rotation and orbit of stars in a dwarf spheroidal are in sync with the rotation of a slightly larger, nearby galaxy — possibly even just another dwarf spheroidal — the gravitational influences of the two galaxies on each other are enhanced, D’Onghia says.
Within 2 to 3 billion years, the gravitational pull would remove many stars from the lower-mass dwarf, D’Onghia says. Because dark matter does not rotate, it would be left behind in the dwarf galaxy. Depending on how closely the rotation of stars and gas aligns in neighboring galaxies, the dwarf spheroidals would end up with varying, but always high, ratios of dark to visible matter.
The proposed interaction could account for dwarf spheroidals, such as the recently discovered galactic duo Leo IV and Leo V, that don’t reside close to a large galaxy like the Milky Way, D’Onghia asserts.
“Certainly this is an idea that needs to be taken very seriously,” comments theorist James Bullock of the University of California, Irvine. “I bet some of the [dwarf spheroidals] formed this way, but I’m not sure if the numbers work out to explain all of them,” he adds.
D’Onghia and her collaborators simulate only the interaction of stars, not gas, cautions Rosemary Wyse of Johns Hopkins University in Baltimore, Md. But D’Onghia says that the rotating gas in a dwarf spheroidal, although more difficult to model than the stars, ought to be removed in a similar manner.
Jorge Peñarrubia of the University of Cambridge in England takes a contrarian view. “In my opinion, the whole problem may be a theoretical misconception,” due to uncertainties about star formation in galaxies, he says. Although dark matter models require that stars form in rotating disks, star-forming regions in the Milky Way indicate that most stars form in clusters instead. If stars in dwarf spheroidals don’t form in rotating disks, the scenario proposed by D’Onghia and her collaborators wouldn’t provide an explanation, he says.