5. Are these galaxies moving toward or away from us? (Circle your choice.) Toward Away NGC...

  

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5. Are these galaxies moving toward or away from us? (Circle your choice.) Toward Away NGC 3147 - Calcium K(393.4 nm)and H(396.8 nm) 1.0 NGC 3368 - Calcium K(393.4 nm)and H(396.8 nm) 0.8 0.8+ 0.6 in 0.6- 0.4+ 0.2+ 0.2+ Cak a 0.0 0.0 390 395 400 405 410 415 390 395 400 405 4 10 415 Wavelength (nim) (b) (a) Wavelength (nm) Figure 9.3 6. (2 pts) The galaxy NGC 3147 is moving faster than NGC 3368. How can you tell? 7. (2 pts) The wavelength shifts of these galaxies are positive, making them redshifts. The redshift of galaxy NGC 3147 is 0.00935, and the redshift of NGC 3368 is 0.00301. From the Doppler formula we know that wavelength shifts are proportional to the velocities of objects. Approximately how many times faster is NGC 3147 than NGC 3368? (Take a ratio of the redshifts and state the results.) Relative intensity Relative intensity 8. (1 pt) How many times farther away is NGC 3147 than NGC 3368? 9. (2 pts) Is there an inconsistency between the relative distances obtained from the redshifts of NGC 3147 and NGC 3368 and the relative distances calculated by the standard ruler method? Comment on your comparison. 10. (2 pts) Think about the underlying assumptions and methods used for the standard ruler and the direct measurements of wavelengths of lines in spectra. Which method is likely to give more accurate results? Explain. 5. Are these galaxies moving toward or away from us? (Circle your choice.) Toward Away NGC 3147 - Calcium K(393.4 nm)and H(396.8 nm) 1.0 NGC 3368 - Calcium K(393.4 nm)and H(396.8 nm) 0.8 0.8+ 0.6 in 0.6- 0.4+ 0.2+ 0.2+ Cak a 0.0 0.0 390 395 400 405 410 415 390 395 400 405 4 10 415 Wavelength (nim) (b) (a) Wavelength (nm) Figure 9.3 6. (2 pts) The galaxy NGC 3147 is moving faster than NGC 3368. How can you tell? 7. (2 pts) The wavelength shifts of these galaxies are positive, making them redshifts. The redshift of galaxy NGC 3147 is 0.00935, and the redshift of NGC 3368 is 0.00301. From the Doppler formula we know that wavelength shifts are proportional to the velocities of objects. Approximately how many times faster is NGC 3147 than NGC 3368? (Take a ratio of the redshifts and state the results.) Relative intensity Relative intensity 8. (1 pt) How many times farther away is NGC 3147 than NGC 3368? 9. (2 pts) Is there an inconsistency between the relative distances obtained from the redshifts of NGC 3147 and NGC 3368 and the relative distances calculated by the standard ruler method? Comment on your comparison. 10. (2 pts) Think about the underlying assumptions and methods used for the standard ruler and the direct measurements of wavelengths of lines in spectra. Which method is likely to give more accurate results? Explain.