Presentation Extraterrestrial Life

1. Intro
- Intellectual curiosity
- 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)

3. Methods o Doppler Spectroscopy
- 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
- Drawbacks:
• 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 o Transit 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 Radius Atmosphere of the planet
Planets temperature

4. Paper
- 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