Class Notes (838,033)
Canada (510,626)
Physics (324)
PHYS 183 (78)
Tracy Webb (34)

Lecture 21

2 Pages
Unlock Document

PHYS 183
Tracy Webb

PHYS 183 – The Milky Way Inside and Out – Tracy Webb Winter 2013 Lecture 21: February 27 , 2013 th  we are going to start with star birth  a star birth is more like a formation event  the single most important feature of a star is it’s mass  it determines everything  but what determines the mass of a star?  nebula: large cloud of gas in the universe  interstellar medium: the gas and dust between stars  in the universe where stars form  newborn stars produce white patches in the cloud where starlight illuminates surrounding gas  clouds look dark where dust particles block the light from more distant stars  dust in the universe is tiny little grains of soot-like ash  interstellar medium is a place where you find a lot of extra energy or energy that is being blocked  most of the matter in giant molecular clouds is in the form of molecules 2H , CO) as opposed to single atoms  molecular clouds usually have very distinct boundaries/edges  they have typical temperatures of 10-30 K (very cold) & densities of 300 molecules per cubic cm (best vacuum’s in physics labs are ~100 molecules per cubic cm)  very cold & very dense  interstellar dust is made of tiny solid particles made of carbon, silicon, iron & oxygen  larger than molecules & made of heavier elements  it also blocks the light from stars behind them  interstellar reddening o dust is better at blocking blue light than red o recall: light interacts with orbits larger than it o there is a general ring of apparently red stars at the edge of the molecular cloud o observing the infrared light from a cloud can reveal new stars within it  wavelengths (like infrared) provide a lot of information about hidden processes  dust grains in the gas glows in the infrared since they absorb energy from new stars (anything with a
More Less

Related notes for PHYS 183

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.