astronomy final homework

In an extrasolar planetary system containing a single planet, the parent star is measured to move about its center of mass every 24 years. Given this, what is the orbital period of the planet?

24 years

The complexity of any life present in EuropaÕs subsurface ocean is mainly limited by the

B) amount of available energy to sustain it

Europa is located outside the SunÕs habitable zone and yet may be habitable. How can this be?

Europa is tidally heated, allowing liquid water to exist beneath its icy surface

Although Titan is roughly the same size as Mercury, Titan has an atmosphere while Mercury does not. How can this be?

Even though TitanÕs gravity is weak, it is much colder, allowing molecules to be trapped in its atmosphere

Which of the following types of stars is NOT suitable for ADVANCED life?

F-type

Even though JupiterÕs moon Io is similar in size to our geologically dead Moon, it is more geologically active than the Earth. How can this be?

Io is tidally heated due to its elliptical orbit, which causes the large tidal forces exerted by Jupiter to constantly change, flexing and distorting its interior

Most of the smallest Jovian moons are most likely

captured asteroids and comets

If life exists in the Europan oceans, it most likely originated

close to volcanic vents on its ocean floor

The wavelengths of radiation coming from a star that is moving toward us

continuously habitable zone

Stars spend 90% of their lives

fusing hydrogen into helium in their cores and slowly brightening

SaturnÕs icy moon Enceladus

has fountains of ice particles and water vapor spraying out from its surface

A- and F-type stars

have lifetimes long enough for planets to form and for simple life to appear, but not long enough for advanced life to develop

O-type stars

have lifetimes too short for planet formation

Jovian moons are typically made of

ice and rock

In the Hertzprung-Russell diagram most stars are found

in the main sequence

Even though Titan has liquid methane on its surface, some internal heat, and plenty of carbon-containing compounds, it is not a suitable place for life as we know it because

it is far too cold, and methane is not a very good biological solvent

The largest Jovian moons, Ganymede and Titan, are

larger than Mercury but smaller than the Earth

How is Titan similar to the Earth?

like the Earth, Titan has an atmosphere made mostly of molecular nitrogen

B-type stars have lifetimes

long enough for planets to form but not for life to appear

The total amount of energy that a star radiates out into space is referred to as its

luminosity

Where has life been found in the Solar System?

nowhere

What is believed to have been the main source of TitanÕs atmosphere?

outgassing from the interior

Like our own moon, many Jovian moons exhibit what is called synchronous rotation. This means that they rotate at the same rate

that they orbit their host planet

G-, K-, and M-type stars

the faster it evolves

What is the definition of a starÕs habitable zone?

the range of distances from the star where liquid water can be stable on the surface of a suitable planet

What is the internal structure of Europa?

thin icy crust, subsurface ocean of water, thick rocky mantle, central iron core

The fact that the strength of gravity decreases with distance means the force of gravity exerted by one object on another (e.g., the Earth and Moon) is greater on the near side than the far side. This effect is commonly referred to as a

tidal force