Figure 10 taken from
Chemin et al., arXiv 0909.3846 (2009)
-
M31 is a distance of approximately 800 kpc from the Earth.
Use the rotation curve above to estimate the its mass.
-
Consider a terrestrial planet like the Earth. An ordinary photo
of the planet from space shows large land masses and oceans.
Image courtesy of
NASA
We can still recognize -- sort of -- these rough features if the photo is degraded
to a lower resolution, like this:
Suppose that we wished to take pictures of a similar planet
around some OTHER star -- pictures as detailed as this,
from which we might learn at least a bit about the nature
of the planet's surface.
- Estimate the linear resolution (in km) of the degraded
image above. Treat this as the minimum linear resolution
required to see continental features.
- Consider the TRAPPIST-1 system, which is known to
contain a number of Earth-ish-sized planets.
What is the distance to this star, according to
Gaia DR3?
- What is the angular resolution required to reach the
linear resolution from part "a" at the distance of
TRAPPIST-1? Express your answer in both radians
and arcseconds.
- Suppose we build an optical interferometer in order
to achieve this angular resolution, one that operates
at a wavelength of λ = 500 nm.
How far apart must be place the elements in order to
achieve this resolution?
Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.