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A History of Ideas - Descartes Cogito Ergo SumFriday, 17th April 2015 12:04 - BBC Radio 4Stephen Fry explains Rene Descartes argument 'Cogito Ergo Sum' - 'I think, therefore I am'. Watch now: OU on the BBC: A History of Ideas - Descartes Cogito Ergo Sum
The RavensSaturday, 18th April 2015 23:05 - BBC World Service Radio
The RavensSunday, 19th April 2015 04:05 - BBC World Service Radio
Thinking Allowed: The Ethnography Award 'Shortlist' 2015Monday, 20th April 2015 00:15 - BBC Radio 4
A History of Ideas - Erving Goffman's Performed SelfAvailable until Thursday, 14th April 2016 08:15Do you have a fixed character? Or do you play many roles based on the situation? Stephen Fry explains Erving Goffman... Watch now: OU on the BBC: A History of Ideas - Erving Goffman's Performed Self
Thinking Allowed: The Ethnography Award 'Shortlist' 2015Available until Friday, 15th April 2016 09:45
A History of Ideas - John Locke and personal memoryAvailable until Thursday, 14th April 2016 11:15
OU on The BBC: A History of Ideas - What does it mean to be me?Available until Wednesday, 13th April 2016 10:45
The Secret History Of Our Streets - Deptford High StreetHow did the "Oxford Street of South London" come to be one of the poorest shopping streets in... Read more: The Secret History Of Our Streets - Deptford High Street
The Election Debate Visualisation ProjectEven though social media is thoroughly embedded in voters’ culture we have yet to come up with an... Read more: The Election Debate Visualisation Project
Writing what you knowDo you want to improve your descriptive writing? This free course, Writing what you know, will... Try: Writing what you know now
Succeed with maths – Part 1[BETA] If you feel that maths is a mystery that you want to unravel then this short 8-week course... Try: Succeed with maths – Part 1 now
Introduction to active galaxies
The field of active galaxies is recognised as one of increasing importance. But how do...
The field of active galaxies is recognised as one of increasing importance. But how do we know there are different kinds of galaxy? What are active galaxies? How are they powered? This unit examines the different types of active galaxy and looks at the crucial role of the active galactic nucleus and the energy source at its heart.
By the end of this unit you should be able to:
- explain how and why the optical spectrum of an active or starburst galaxy differs from that of a normal galaxy;
- explain how and why the broadband spectrum of an active or starburst galaxy differs from that of a normal galaxy;
- describe briefly the observed features of starburst galaxies and the four main classes of active galaxies (quasars, radio galaxies, Seyfert galaxies and blazars);
- understand the evidence that indicates the presence of a compact active galactic nucleus (AGN) in active galaxies;
- explain why an AGN should emit broad lines, narrow forbidden lines and continuous radiation;
- give an account of an accreting massive black hole as the engine of the AGN and relate its luminosity to the mass accretion rate;
- outline some of the outstanding problems relating to the evolution of active galaxies.
- Current section: Introduction
- Learning outcomes
- 1 Overview
- 2 The spectra of galaxies
- 3 Types of active galaxies
- 4 The central engine
- 5 Models of active galaxies
- 6 Outstanding Issues
- 7 Unit Summary
Introduction to active galaxies
Active galaxies provide a prime example of high-energy processes operating in the Universe. This unit introduces the evidence for activity from the spectra of some galaxies, and the concept of a compact active galactic nucleus as a unifying model for the observed features of several types of active galaxy. It also develops the key skill of applying arithmetic and simple algebra to solving scientific problems.
This course is an adapted extract fromt he course