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ASTROPHYSICS NOTES - CAMBRIDGE UNIVERSITY SYLLABUS 2022.
Author of this note Mr. K. Prasad BSc from University of Calicut, MSc from university of Delhi, and M.B.A from IGNOU Delhi, These notes were prepared during my teaching session for graduate students and 11th and 12th class of my college Physics department. This note is helpful for under graduate students and junior level graduates. I declare that these notes are my original works based on my knowledge in physics and the books mentioned below are the reference books I used for preparing these notes. TABLE OF CONTENTS, (1) Electromagnetic radiation, (2) Electromagnetic Theory, (3) Properties of Electromagnetic Radiation, (4) Electromagnetic Spectrum, (5) Waves and their Qualities,
(6) Gamma-rays definition, (7) X-rays definition, (8) Ultraviolet radiation, (9) Infrared radiation, (10)Frequency modulation, (11)Transparency of the atmosphere, Reference Books
**- Shu, F.H., The Physical Universe, chaps. 5-10, University Science Books, California, (1982).
- Accretion Power in Astrophysics (Cambridge Astrophysics) Hardcover – 17 Jan. 2002 by Juhan Frank, Andrew King, Derek Raine. CUP † Carroll, B.W. & Ostlie, D.A. An Introduction to Modern Astrophysics (Addison- Wesley) 2017. Goldstein Classical Mechanics, Addison-Wesley (2nd edition 1980). † Binney, J. & Tremaine, S.D. Galactic Dynamics, Princeton University Press (2008). Landau & Lifshitz Mechanics, Pergamon (3rd edition 1976, reprinted 1994). † Binney, J. & Merrifield, M. Galactic Astronomy, Princeton University Press (1998). Sparke, L.D. & Gallagher, J.S. Galaxies in the Universe - An Introduction CUP (2000) (ISBN 0- 521 - 59740 - 4)**
Electromagnetic waves can travel through empty space. Waves other than electromagnetic waves need to go through some substance. For instance, sound waves will require a solid, fluid or gas to go through. The speed of light which is 2.99792458 x 108 m/s is consistently consistent. Frequency is ordinarily portrayed by the symbol 'λ'. It is characterized as the distance between two most close to focuses in phase with one another. Consequently, two neighboring crests or troughs on a wave are isolated by a distance of a single complete wavelength. Electromagnetic Spectrum,
Electromagnetic spectrum is the range of frequencies Electromagnetic radiations alongside their related frequencies and photon energies. It comprises of Gamma- beams, X-beams, ultraviolet beams, infrared beams, radio waves and microwaves. Electromagnetic radiations have a great many frequencies, frequencies and photon energy levels. These waves travel at the speed of light in vacuum. Waves and their Qualities Electromagnetic radiation happens when a nuclear molecule, similar to an electron, is accelerated rapidly by an electric field, making it speed up. Electromagnetic waves and their attributes is made sense of momentarily in the points highlighted below. Frequency Frequency (λ) is the distance between progressive crests of a wave, particularly focuses in an electromagnetic wave or sound wave. It tends to be basically characterized as the distance of one full cycle of the oscillation. If 'λ' is the frequency, 'c' is the speed of light and 'ν' is recurrence. Then we can infer the connection given beneath. c = λ ν The shorter the wavelength, the more prominent the frequency and, the higher the energy. Amplitude Amplitude is the separation from the center of the wave to the greatest vertical displacement of the wave. Bigger the amplitude, the higher the energy and the lower the amplitude, the lower the energy. Amplitude informs us concerning the brightness or intensity of a wave compared with different waves. Frequency The number of cycles in each second is characterized as frequency. It is characterized as Hertz (Hz) or sec-1. On the off chance that 'E' is the energy, 'h' is
your body in different shades of black and white. This is because different tissues absorb different amounts of radiation. Use of x ray is to produce images of internal tissues, bones, and organs on film or digital media. Standard X-rays are performed for many reasons, including diagnosing tumors or bone injuries. There are two types of X-ray generated: characteristic radiation and bremsstrahlung radiation. Ultraviolet radiation Ultraviolet radiation is .Invisible rays that are part of the energy that comes from the sun. Ultraviolet radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB. UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and sun tanning. Infrared radiation, Infrared radiation, that portion of the electromagnetic spectrum that extends from the long wavelength, or red, end of the visible-light range to the microwave range. Invisible to the eye, it can be detected as a sensation of warmth on the skin. Frequency modulation waves, Frequency modulation or FM is a form of modulation which conveys information by varying the frequency of a carrier wave; the older amplitude modulation or AM varies the amplitude of the carrier, with its frequency remaining constant. In FM broadcasts, sound signals are encoded by changing the frequency of radio waves. Frequency modulation allows FM waves to encode more information than does amplitude modulation, so FM broadcasts usually produce clearer sounds than AM broadcasts. Transparency of the atmosphere,
The environment is in consistent movement with evolving temperatures, air flows or wind and weather conditions fronts, making stars sparkle. The pictures of glimmering stars are exceptionally twisted and how much light contacting us through the air is likewise impacted, so it changes from one moment to another and the star sparkles. In the event that the stars are glimmering impressively, this is known as "poor" seeing circumstances. At the point when the star pictures are consistent, this is known as "great" seeing circumstances. Poor seeing is most perceptible while noticing planets, close twofold stars and the Moon, though profound sky items, for example, nebulae and universes are less impacted by unfortunate seeing circumstances. For deep-sky objects, the most important factor is the transparency of the atmosphere (a measure of how clear the sky is on a given night–determined by clouds, dust and haze). Seeing conditions and transparency will vary widely from site to site, from season to season, and from night to night.
