•Question 7 (1 point) If the O6 V star in
the Orion Nebula
is magnitude 5.4, how far away is the nebula? (Hint: Use spectroscopic parallax and look at plots
of the HR diagram
showing absolute magnitudes on one axis.) Choose the best answer below.
•a.10 parsecs.
•b.120 parsecs.
•c.300 parsecs
•d.1600
parsecs
•e.10000 parsecs
•an
HR diagram, estimate M = -6 or so.
So d = 10 (m-M+5)/5 is roughly 103+ and we are done since only one answer is between 1000 and 10000. – Should work on the board.
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