Test Ques4ons. Median Grade: 82/100 High Score: 99/100

Day 11: Stars Review of Test Ar4cle Sharing Reading/Mastering Astronomy Ques4ons Lecture on Spectral Type Break Lecture on Hertzsprung- Russell Diagram L- T: H- R Diagram, p 117 Summary

Test Ques4ons Median Grade: 82/100 High Score: 99/100

Did the midterm do a good job of tes4ng informa4on we emphasized in class? A. Very much so either I knew the informa4on or I should have known it B. PreVy good it seemed fairly appropriate to the class C. Somewhat some of the ques4ons were out of ley field but it mostly worked D. Not so much some of it I recognized but a lot I can t remember covering E. (all colors) Not at all. What were you thinking?

Ar4cle Review

Atmosphere of Star

Absorp4on Spectra

Cecilia Payne- Gaposchkin

Which Hydrogen Atom will not produce absorp4on lines? A. Hydrogen atom with one electron in ground energy level B. Hydrogen atom with one electron in second energy level C. Hydrogen atom with two electrons, one in ground energy level and one in second energy level D. Ionized hydrogen (Hydrogen atom with no electrons)

What type of hydrogen gas is least likely to produce absorp4on lines? A. Extremely hot hydrogen gas B. Warm hydrogen gas C. Cold hydrogen gas D. Hydrogen gas in a strong magne4c field

Hydrogen is ionized Hydrogen is not ionized. Many electrons in 2 nd energy level Hydrogen is not ionized. All electrons in ground energy level

Hydrogen lines in visible part of the spectrum are produced by atoms star4ng at the second energy level

What gas will produce the most hydrogen absorp4on lines in the visible part of the spectrum? A. Extremely hot gas: all hydrogen is ionized B. Fairly hot gas: all hydrogen electrons in very high energy levels C. Warm gas: many hydrogen electrons in second energy level D. Cold gas: all hydrogen electrons in ground energy level

Hydrogen is ionized Hydrogen is not ionized. Many electrons in 2 nd energy level Hydrogen is not ionized. All electrons in ground energy level

Spectral Type Oh Be Fine Girl/Guy Kiss Me

Stellar Absorp4on Lines Require gas of a certain element of just the right temperature to be produced Too hot, and the gas of that element is ionized Too cold, and electrons are all in ground level so they can only produce lines for energy transi4ons star4ng at ground We can, therefore, use lines to tell us stellar temperatures

Break

Income vs. Mass

Hertzsprung- Russell Diagram Luminosity Surface Temperature

Hertzsprung- Russell Diagram

Hertzsprung- Russell Diagram Magnitudes

L- T: H- R Diagram, page 117

Hertzsprung- Russell Diagram

The stars Antares and Mima each have the same luminosity. Antares is cooler than Mima. Which star is larger? A. Antares B. Mima C. Both stars are the same size D. There is insufficient informa4on to determine this

The stars Antares and Mima each have the same luminosity. Antares is cooler than Mima. Which star is larger?

Size Luminosity Temperature

Rigel is much more luminous than Sirius B. Rigel and Sirius B have the same temperature. Which star has A. Rigel B. Sirius B the greater surface area? C. The have the same surface area D. There is insufficient informa4on to answer this ques4on

Rigel is much more luminous than Sirius B. Rigel and Sirius B have the same temperature. Which star has the greater surface area?

Size Luminosity Temperature

Main Sequence: Hydrogen Burning Luminosity Temperature

Giants/Supergiants: Dying Stars Luminosity Temperature

White Dwarfs: Dead Stars Luminosity Temperature

Lalande is a nearby star half the mass of the Sun. It is in gravita4onal equilibrium (i.e., it is neither expanding nor contrac4ng). What force supports Lalande and keeps it from collapsing in on itself? What force binds Lalande together and keeps it from exploding outward? How does the strength of this force for Lalande compare to the strength of this same force for the Sun? What is the net force this star is experiencing? How does the temperature at the center of Lalande compare to the temperature at the center of the Sun? How does the rate of fusion at the center of Lalande compare to the rate of fusion at the center of the Sun?

Hertzsprung- Russell Diagram

Different Mass Main Sequence Low Mass High Mass (0.1 Solar Mass) (50 Solar Masses) Dim (0.001 Solar Luminosity) Cool (3000 K) Red Small (0.1 Solar Radius) Long- lived (100 Billion years) Bright (1 Million Solar Luminosity) Hot (30,000 K) Blue Large (10 Solar Radii) Short- Lived (10 Million years)

Summary Absorp4on line spectra and peak wavelength tell us stellar temperature Absorp4on lines depend on the type of gas available in the stellar atmosphere Stars can be sorted by temperature/stellar type: O, B, A, F, G, K, M The Hertzsprung- Russell diagram shows stars divided into Main Sequence, Giants, and White dwarfs Higher mass stars are hover, bigger, and short lived

Homework LT: H- R Diagram Reading: Ch. 16.1 and 16.2 (p 512-526) MasteringAstronomy: Star Forma4on