Class Notes (807,247)
Brock University (11,830)
Astronomy (161)
ASTR 1P01 (93)
Lecture

# Friday November 2nd.docx

2 Pages
114 Views

School
Brock University
Department
Astronomy
Course
ASTR 1P01
Professor
Bozidar Mitrovic
Semester
Fall

Description
Friday November 2 , 2012 Astronomy Lecture: Properties of stars derive from the light, which they emit (CH.8): 1) Measure the distances of starts - for nearby stars the distance is deduced from the measurement of the parallax angle - 1au/d = sin p or d= 1au/sin p = 1au/p (for small angles) - the units can be chosen such that d (in parsec (p))= 1/p (in seconds of arc (or arc seconds)) - 1pc= 3.26 LY = 3.3 LY - for the closest stars alpha-centauri p=0.76 arcseconsds - d (distance) = 1/p (parallax angle in seconds of arc) - p= 1/d Test: - p= 1/50 = 2/100 = 0.02 - larger parallax angle the closer it is to us - closer start is a-centauri A .76 seconds - step 1: d= 1/0.5 pc=2pc - step 2: 1 pc= 3.3 LY - d= 2x3.3 LY= 6.6 ly - p = 160 LY/3.3 LY PC = 50 - d = 50 pc = 50pcx 3.3 = 160 LY Monday November 5 , 2012h 2) Luminosity of a Star (as determined from its brightness and distance) - luminosity of a source L= amount of energy which it emits per unit of time (measured in watts (w)) - the luminosity of our sun L = 4x10*26 w (hydro bill would be \$8x10*19/second) - energy released in explosion of 100 billion 1 megaton nuclear bombs - brightness of a source B= amount of energy received
More Less

Related notes for ASTR 1P01

OR

Don't have an account?

Join OneClass

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

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Just a few more details

So we can recommend you notes for your school.