TO INVESTIGATE RADIATION OF STARS Flashcards
What is a blackbody?
A body that absorbs all electromagnetic radiation that falls upon it (perfect emitter)
What is a continuous spectrum?
Full rainbow
How can white light be split into a continuous spectrum?
Glass prism, Diffraction grating, Spectrometer, Spectroscope
What is a rainbow spectrum with dark lines across it known as?
Absorption Spectrum
How are absorption lines produced?
Dust and gas absorb certain wavelengths (colour) of light which appear as dark lines at the missing wavelengths
What do absorption lines tell us about a star?
Chemical composition (elements), how far away it is, how fast it’s moving
What is Wien’s displacement law?
λmax = W / T where W = 2.90x10⁻³m K
What name is given to the temperature where particles have no energy and exert no pressure?
Absolute zero
What temperature is absolute zero?
0 kelvin = -273.15 degrees celsius
What is 25deg celsius in kelvin?
298.15K
What is Stefan’s law?
P = A σ T⁴ where σ = 5.67x10⁻⁸ Wm⁻²K⁻⁴
What is luminosity?
Total energy emitted per second (same as Power)
What is the inverse square law of light?
I = P / 4πR²
What does the R stand for in the inverse square law equation?
Distance to the object
What is a light year?
Distance light travels in 1 year
What is an Astronomical Unit?
Distance between the Earth and the Sun
What are 3 units used to measure stellar distances?
Light year, Astronomical Unit and Parsec
What is meant by multiwavelength astronomy?
Looking at objects using different telescope to find as much information as possible
Why are most ground based telescope radio telescope?
Radio waves can travel through the atmosphere
What does the presences of 21.1cm wavelength radio waves indicate?
Atomic Hydrogen clouds
How is synchrotron radiation produced?
Electrons spiral around magnetic field and give off synchrotron radiation
What does CMBR stand for?
Cosmic Microwave Background Radiation
What is the CMBR?
Left over energy from Big Bang. High energy gamma rays stretched into microwaves
