Question
12: You identify the Balmer series absorption lines in the spectrum of a hot type
O star, but notice that the lines are shifted from their laboratory
wavelengths. For instance, H-beta, normally seen at 486 nm appears at 488 nm.
What can you deduce about the motion of this star relative to Earth? USE
THE DOPPLER EQ:
v/c = (λobs/λrest) – 1;
v/c = (488/486) –
1 = 0.004115
V = 0.004 x 300,000
km/s = 1200 km/s away
from us (c)