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ASTR 1200 Announcements. Exam #1 in class, next Tuesday, October 7 Have posted review sheet and sample exam Help room: Mondays 3-5,Duane G2B90 Review Today Josh review/help session today after class?. Website http://casa.colorado.edu/~wcash/APS1200/APS1200.html. Structure of the Exam.

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ASTR 1200 Announcements

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Astr 1200 announcements

ASTR 1200Announcements

Exam #1 in class, next Tuesday, October 7

Have posted review sheet and sample exam

Help room: Mondays 3-5,Duane G2B90

Review Today

Josh review/help session today after class?

Website

http://casa.colorado.edu/~wcash/APS1200/APS1200.html


Structure of the exam

Structure of the Exam

Closed book.

Calculators strongly recommended. (Check batteries!)

Pencils are a good idea for the calculations. (but not necessary)

Formulae and constants you need will be provided.

Just like the sample exam.

Will not be a test of time. Should be finished in under one hour. But will have full 75minutes to complete it.


How to study

How to Study

Knowledge

Facts. Multiple Choice

Fast. Do these first.

Conceptual

How things work. Written Answers

Calculations

Identify and use the formulas.

These take longer. Do them last.

Homeworks

Redo them.

Do additional exercises.

Lecture Notes

Go through each powerpoint slide and make certain you understand.

Textbook

Background reading of for explanation of individual points.

Test yourself to identify weak areas using review sheet and sample exam.


Material covered

Material Covered

Drakes Equation and prevalence of Life in the Universe

Scientific Notation

Sizes of things

Formation of Solar System

Position, velocity, acceleration

Newton’s Laws

Orbits

Escape Velocity

Surface Gravity

Orbital Period

Structure of Sun

Nuclear Processes

Solar Activity


Material covered1

Material Covered

Our place in the galaxy

Light years and parsecs

Parallax

Proper Motion

Brightness

Magnitudes and Absolute Magnitudes

Concept only from here on:

Electromagnetic Spectrum and its parts

Spectroscopy

Spectral Types


The spectral types

The Spectral Types

Table 15.1  

The Spectral Sequence


The h r diagram plot of brightness vs temperature

The H-R DiagramPlot of Brightness vs Temperature

-5

Giants

Rigel

Capella

0

Sirius

Brightness

Procyon

Sun

Main Sequence

+5

a Cen B

White Dwarfs

+10

Sirius B

Prox Cen

+15

K

M

F

G

A

B

O

Spectral Type


Astr 1200 announcements

The H-R Diagram


The main sequence

The Main Sequence

Stars Differ By:

Mass

Age

Composition

Nothing else!

And composition doesn’t vary

Age and Mass only.

Those on main sequence are all

burning H so age drops out.

MS is function of MASS only!!!


Full artistic h r

Full, Artistic H-R

As mass of

MS star increases,

both R and T

increase

increasing

size

sAT4

T constant

on any vertical

line


Newly formed star

-5

Giants

Rigel

Capella

0

Sirius

Protostar

Procyon

M

Sun

Main Sequence

+5

a Cen B

White Dwarfs

+10

Sirius B

Prox Cen

+15

K

M

F

G

A

B

O

Spectral Type

Newly Formed Star

Large,

Low T.

Settles down

to MS

Then sits while

burning H


Ms lifetime

MS Lifetime

What determines amount of time a star stays on Main Sequence?

Just like a kerosene heater: Amount of fuel and rate of burn.

More Mass = More Fuel

More Luminosity = Greater Burn Rate

We can scale from the Sun: M = 1M L = 1L

Sun lasts 1010 years

M in solar masses

L in solar luminosities


Some lifetimes

Some Lifetimes

MassLuminosityLifetime in Billion Years

Sun1110

Sirius2102

Prox Cen.4.0014000

Rigel810,000.008

Dinky little stars like Prox Cen will last trillions of years

Huge stars like Rigel are gone in a few million

There aren’t many large stars out there, because they don’t last.

10,000 O stars of the 100,000,000,000 Milky Way stars


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