E2+STELLAR+RADIATION+AND+STELLAR+TYPES

Back to IB PHYSICS > IB ASTROPHYSICS OPTION E1-E4 are the sections required for the SL option =STELLAR RADIATION AND STELLAR TYPES= media type="custom" key="12499124"
 * E1 INTRODUCTION TO THE UNIVERSE || E2 STELLAR RADIATION AND STELLAR TYPES || E3 STELLAR DISTANCES || E4 COSMOLOGY || E5 STELLAR PROCESSES AND STELLAR EVOLUTION || E6 GALAXIES AND THE EXPANDING UNIVERSE ||

State that fusion is the main energy source of stars

[|ANIMATION OF THE FUSION PROCESS]

Students should know that the basic process is one in which hydrogen is converted into helium. They do not need to know about the fusion of elements with higher proton numbers. NUCLEAR FUSION: Inside a star, protons fuse to make helium in a complex reaction also producing positrons, neutrinos and gamma rays. Explain that, in a stable star (for example, our Sun), there is an equilibrium between radiation pressure and gravitational pressure. STABLE STAR: There is a balance between collapse due to gravitational force and expansion due to KE of particles (radiation pressure). The star’s source of energy keeps it stable. Define the //luminosity// of a star. LUMINOSITY (L): The total amount of energy emitted by the star per second. Unit: watt. Depends on the star’s temperature and its size [|REAL LIFE CALCULATION OF LUMINOSITY OF SUPERNOVA] - Rhett Allain blog in Wired magazine



Define //apparent brightness// and state how it is measured. APPARENT BRIGHTNESS (b): The amount of energy received per unit area per second. Unit: Wm -2 media type="custom" key="12392586"

Apply the Stefan–Boltzmann law to compare the luminosities of different stars. State Wien’s (displacement) law and apply it to explain the connection between the colour and temperature of stars.

Explain how atomic spectra may be used to deduce chemical and physical data for stars.

Students must have a qualitative appreciation of the Doppler effect as applied to light, including the terms red-shift and blue-shift. Describe the overall classification system of spectral classes. Students need to refer only to the principal spectra classes (OBAFGKM).

TYPES OF STAR media type="custom" key="25691258" Describe the different types of star. MAIN SEQUENCE: Most stars are like this. GIANT STAR: Cool large star RED SUPERGIANT: Very large, very cool, very rare WHITE DWARF: Small, very hot star

Discuss the characteristics of spectroscopic and eclipsing binary stars. [|ECLIPSING BINARIES SIMULATION]

THE HERTZSPRUNG-RUSSELL DIAGRAM [|INTERACTIVE H-R DIAGRAM LINK] the best one I've found, though let me know if you see a better one.

Identify the general regions of star types on a Hertzsprung–Russell (HR) diagram. SIMPLE H-R DIAGRAM IN WORD TO DOWNLOAD Main sequence, red giant, red supergiant, white dwarf and Cepheid stars should be shown, with scales of luminosity and/or absolute magnitude, spectral class and/or surface temperature indicated. Students should be aware that the scale is not linear. Students should know that the mass of main sequence stars is dependent on position on the HR diagram.