Where are large dust clouds predominantly located in the galaxy M51?
within or on the edges of the spiral arms
Where are the ionization nebulae predominantly located in the galaxy M51?
within or on the edges of the spiral arms of the galaxy
Why are the ionization nebulae so bright?
They are regions where gas is ionized by hot, young stars.
To calculate the dashed orbits from the stellar positions, astronomers had to assume that __________.
if they observed for many more years, the dots would trace out ellipses
To determine the mass of the central object, we must apply Newton's version of Kepler's third law, which requires knowing the orbital period and average orbital distance (semimajor axis) for at least one star. Let's consider the star with the smallest orbit, which is represented by red and pink dots. What is the approximate orbital period of this star?
Look again at the orbit of the star with the smallest orbit, represented by red and pink dots. By comparing the orbit to the scale bar shown on the diagram, you can estimate that this orbit has a semimajor axis of about _____.