Question

A À cloud of He-+ in our galaxy shows emission lines in the optical at 4697.9 and 6562.1 A. Explain these observations with quantitative arguments, in- cluding what they mean for the potential motion and velocity of the cloud.

Answer 1

From data of He^+ lines we can write that it ranges from lambda_A = 4387.93 A degrees to lambda_B = 6678.15 A degrees But we see from the Galaxy, the observed lines are lambda_A^� = 4697.9 A degrees and lambda_B^� = 6562.1 A degrees As lambda_A wavelength is increased in observed we can conclude this is suffering Redshift So this part is receding from earth. with velocity From delta lambda = v/c lambda or, (4697.9 - 4387.93) = v/c times 4387.93 or, v = 0.071 c c = speed of light or, v = 0.071 times 3 times 10^8 m/s or, v = 2.12 times 10^7 m/s \r\n For lambda_B wavelength we observe a decrease in wavelength so blue shift. So this part is approaching towards earth. Therefore delta lambda = v/c lambda or, (6678.15 - 6562.1) = v/c times 6678.15 or, v = 0.017 c or, v = 5.21 times 10^6 m/s so the cloud of He^+ ion is rotating