Lecture 4 (+Lecture 3 cont) Flashcards
What are the four eons of the earth?
Hadean 4Gyr - 3.8 Gyr (200)
Archean 3.8Gyr - 2.5Gyr (1300)
Proterozoic 2.5Gyr - 650Myr (1850)
Phanerozoic 650Myr - Now (650)
(HAPP)
When did Zircon analysis indicate the presence of H20 and what did this indicate?
About 4.4Gyr, the existence of an atmosphere
What was the early earth like?
Major movements in the crust, tectonics, as well as severe volcanic activity
Large amounts of radioactivity 🡺 heating
+ contraction + latent heat left from the merger of the planetesimals. + the bombardment
How do we know the inner core must be solid in some way?
It deflects seismic waves.
What was the atmosphere of the young earth like?
A much denser atmosphere. Probably originated in planetesimals/comets falling down on earth but also outgassing(Volcanoes). The early earth had a reducing atmosphere(oxidizing today). Reducing atmospheres does not form oxides (Like rust), but rather like C+H = CH4.
How much higher density does venus atmosphere have compared to earth?
About 90 times. They were similar to start out, but Venus was always hotter and therefore lost more of its water.
What was the Lunar study?
1990, “Mission to the moon” Study exoplanets and astrometry best cases for interferometry.
What were the PRISMA and STARS mission studies?
Two missions originating in Helio- and stellar seismology, high precision photometers
Describe the radial velocity method.
They find exoplanets via observing the doppler effect in the host stars spectrum. This can help to derive the mass of the planet if the orbital inclination is known.
Which stars are easiest to observe with the radial velocity method?
F,G,K,M since they have a large number of absorption lines which make it easier to measure wavelength shifts.
Describe the transit method? (And pros/cons)
Dip in the flux from a star is detected when a planet is transiting. The inclination wrt line of sight can be measured and the radius of the planet can be derived.
\+Allows radius measure \+Lots of information can be gathered (albedo, atmosphere comp, obliquity) -Low probability -Most sensitive to close-in planets -Produces many false-positives.
What do we need to know if we want to know the exoplanetary mass, radii with a better precision?
The parameters of the star with the same precision.
Characterization of exoplanets needs…?
Characterization of stars
What was the Darwin project?
A project in 1996 to detect earth-like planets around nearby stars and analyze the composition of their atmosphere and ability to sustain life. A space interferometer.
What was the CoRoT mission?
Searching for planets a type similar to earth and studying the inner parts of stars measuring changes in light output. Discovered about 35 new planets.
What was the TESS mission?
All sky survey monitoring about 500 000 stars of type F5-M5 with 2 years mission lifetime looking for transiting exoplanets.
What was the Kepler mission?
Kepler was a space telescope designed to survey a portion of the milky way galaxy in search of exoplanets. It has confirmed more than 2600 bona fide planets.
What was the CHEOPS mission?
A “cheap” mission to study stars known to host exoplanets closer to make more precise measurements of transit.
