-Disocover the universe surrounding us
-Understand how other planets formed in order to understand how our own planet formed -How we came to be
2.1st planet that was discovered (1995)
-They track variations in the star’s spectrum (51 Pegasi) -Conclude that there is a companion orbiting the star
•Min mass: 0.5 Mj (1mj= mass of Jupiter)
•Orbiting at: 0.05 AU (1AU= distance from earth to sun)
-Just like the star causes a planet to move in an orbit around it, the planet causes its host star to move -If a star is being orbited by a planet, the radial velocity of the star changes as it moves towards and away from the observer. -This back and forth motions causes a shift in the stars spectrum -This is the same effect as an ambulance that moves towards and away from you. -As the planet moves towards the observer: moves to shorter wavelengths, higher frequency (blue shit) -As the planet moves away from the observer: moves to longer wavelengths, lower frequency (red shift) -The greater the radial velocity, the greater the shit
-We can determine: minimum mass and period
•If the planet is orbiting along our line of sight, then the min mass measured is the true mass of the planet •But if its shifter, we must correct to find the true mass of the planet oTransit method
-As the planet transits in front of its host star, the observed flux (brightness) of the planet drops -The drop in the light varies with the size of the planet (small planet small photometric effect) -Allows to determine: estimate of mass
Atmosphere of the planet
-Astrophysics/ astrobiology goal: find earth planet in habitable zone -Extraterrestrial life is carbon based and needs water.
-What is a habitable zone?: Sufficient atmospheric pressure to have liquid water on its surface and benign climate -Scientists use Doppler spectroscopy...