lecture03 - Astronomy Picture of the Day The Small...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Astronomy Picture of the Day The Small Magellanic Cloud
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Homework 1 is due in the P20A drop box on the 4th floor of Reines Hall by 8:30 on friday morning Writing out the answers by hand is fine (pencil is ok) Make sure to show your work for the mathematical questions! Eric will go over the solutions in discussion section on friday Reminder: homework
Background image of page 2
Black-body radiation: review An ideal black-body absorbs all light incident on it If we compare 2 black-body emitters having the same size but different temperatures, the hotter black-body will: emit more radiation overall (i.e., it will be more luminous) emit more photons at any given wavelength have a spectrum peaking at shorter wavelengths have a bluer color The wavelength at which a star’s spectrum peaks is a measure of its surface temperature
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
T = 7000 K T = 5800 K T = 4500 K The Spectrum of Black-Body Radiation
Background image of page 4
λ max T = 2.9 × 10 7 Å K A relationship between the temperature of a black-body emitter and the wavelength at which its spectrum peaks: Wien’s Law Example question: If a star’s spectrum peaks at a wavelength of 2900 Å, what is its surface temperature?
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Luminosity and Brightness Luminosity means the amount of energy radiated by an object per second (the same thing as Power) Luminosity can be measured in Watts Brightness refers to how bright an object appears as seen by an observer This depends on both the object’s luminosity and on its distance from the observer
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/20/2008 for the course PHYS 20A taught by Professor Staff during the Fall '02 term at UC Irvine.

Page1 / 26

lecture03 - Astronomy Picture of the Day The Small...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online