Question

1. Predict and interpret the effects of Doppler shift
2. Relate the three types of spectra to the physical situations that form them
3. Relate spectral lines and atomic structure
4. Relate stellar properties and the OBAFGKM classification system.
5. Identify the major steps of stellar evolution in name and on the HR diagram.
6. Predict the ages of stellar clusters based on their color-magnitude diagrams.
7. Relate supernovae and compact objects to the stars that produce them.
8. Predict how light moves near massive objects.
9. Explain how black holes are observed.
10. Use the astronomical distance ladder.
11. Compare and contrast disk and elliptical galaxies.
12. Describe the content and history of the Milky Way.
13. Explain the evidence for dark matter.
14. Relate the Hubble plot and the age of the universe.
15. Describe the evolution of the Universe's size, temperature, density, and composition.
16. Describe evidence for the Big Bang model, beyond the expansion of the Universe.

Answer 1

Interpretation of Red and Blue shifts can be chareaterized by the relative difference between the observed and emitted wavelengths or frequency of an object. This differnce is measured by a dimensionless quantity 'z' which is defined by in terms of wavelengths. or 1+z = . After measuring z based on the value of z whether +ve or - ve we can interpret that blue shift (z<0) are associated with the object approaching the observer and red shifts(z>0) are associated with objects receding from the observer. Similar arguement can be applied to weak and strong gravitational fields also

2 Three types of spectra namely continous, obsorption and emission can be analysed with a prism.

a. Hot and highly dense energy source when pass through a prism we can obtain a continuous spectrum (a complete rainbow of colors for visible light) for all form of light.

b. when excited atoms within a hot cloud of gas gives off only particular wavelength of light and produce an emission spectra, a series of bright spectral lines against a dark background.

c. when light from a hot dense object pass through a cool cloud of gas, the atom within the cloud can absorb particular wavelength of light and produce an absorption line spectrum among the wavelengths of the spectrum

3. The spectral line associated with each and every atomic structure is unique as the electrons transition from one level to another level plays a key role in identifying the element's differnt properties.

4. Based on the spectral colors we can classify the stars as follows

Color - Spectral class

Blue - O

Blue-white - B

White - A

Yellow- white - F

Yellow - G

Orange - K

Red - M