Question

"What if a galaxy was not tilted but was positioned toward us perfectly face-on, so stars in the galaxy are neither approaching nor receding from us, from our point of view. Would the Tully-Fisher technique work?a.Yes, the galaxy is still rotating, so we will measure a Doppler shift.b.No, there is no motion towards or away from us. In this case, there is no Doppler shift we can measure.c.Yes, we can see the galaxy swirling in the sky.d.No, the light from the center of the galaxy would be too bright.

Answer 1

b.No, there is no motion towards or away from us.

Step-by-step explanation:

The Tully–Fisher technique works by knowing the correlation for spiral galaxies between their luminosity and how fast they are actually rotating.

If a galaxy was not tilted but was positioned towards us face on, so the stars in the galaxy are neither approaching nor receding from us, from our point of view, using the Tully-Fisher technique would be useless because if the galaxy is neither approaching nor receding from us, we cannot know its intrinsic brightness.

The further away a galaxy is, the dimmer it becomes, but the nearer a galaxy is, the brighter it appears.