This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Asteroid types Asteroids shine by reflected sunlight Not all wavelengths are equally reflected. Reveals the presence of different materials Information in both the shape of the spectrum, and the presence of absorption features Identifies different classes of asteroids Stony and metallic asteroids are found in the inner belt, while carbonaceous chondrites are more distant. Igneous rock is more commonly found in the inner belt This is likely imprinted at the time of formation Tells us something about the temperature structure of the solar nebula Outermost moons of Jupiter, Saturn, Neptune and two moonlets of Mars: About half of these have retrograde orbits Low reflectivity, like the distant (>2.5 AU) asteroids Phoebe (retrograde moon of Saturn) clearly a C- type (carbonaceous chondrite) asteroid Others are controversial in some ways resemble types of asteroids, but not others could indicate that they are different from asteroids. Asteroids: Heating Many asteroids are made up of igneous rock, showing that they were once heated. The amount of energy required to raise the temperature by 1K is known as the specific heat capacity : u v m k c 3 (for solids) where k=1.38x10-23 J/K is the Boltzmann constant, and is the mean molecular mass. The internal energy of a mass M is MT c kT m M NkT E v u = = = 3 3 int int , where N is the total number of particles. Solar : The energy absorbed from the Sun, by an object of radius R at a distance r , is ( ) ( ) 2 2 2 2 4 1 4 1 r R L A R r L A L Sun V Sun V = = This keeps the surface heated to a temperature K AU r A A T IR V / 280 1 1 4 / 1 Gravity: The total amount of gravitational potential energy available is R GM E g 2 5 3 = (for a uniform sphere....
View Full Document
- Winter '09