M&P FINAL EXAM Flashcards
What exoplanet detection method was there pressure on NASA to use?
Direct Imaging
Define factors necessary for defining “earth-like”
Radius = 0.1 - 2.0 Earth Radii
Mass = 0.001 - 10.0 Earth Masses
Habitable Zone Factors (distance from star, orbit size, stellar stype, terrestrial/jovian)
Whether planets can be earth-like without an atmosphere
Tidal Lock
Define the mass & radius factors when defining “earth-like”.
Mass & radius => density => composition (solid or liquid)
If it can hold an atmosphere
With orbit size, tells us temperature
Define the habitable zone factors when defining “earth-like”.
Distances from the star where surface T allows for liquid water
Depends on orbit size & stellar type
Terrestrial or Jovian => mass & radius
Exoplanet detection methods only yield ⅔ measurements: orbit size, mass, & radius
Define the atmosphere factors when defining “earth-like”.
Protection from a star
Chemical reactions at surface
Greenhouse Effect => higher T
Habitability
Chemical phase cycles
Define the tidal lock factors when defining “earth-like”.
Asymmetries in planet density => synchronous rotation (more likely if planet is big or orbit is small)
Ratio of near & far side forces = (R + r)^2 / (R - r)^2 = 18% Earth tidal force stronger than sun’s
Consequences: liquid water unlikely (one side water other ice), terminator most habitable region, intense wind storms
What are some orbiting tools for finding exoplanets?
2003 - 2020 Spitzer IR telescope
- Transit method
- 5/7 TRAPPIST 1 exoplanets
2009 - 2018 Kepler Satellite
- Transit method
- 2,662 confirmed & 2000 candidates
- 2013 50% known exoplanets
- Limited field of view (1/400 of whole sky)
2013 - Present GAIA
- Map stars in 3D & measure brightness variations
- Sees whole sky
- 300 candidates & 2 confirmed
2018 - Present TESS
- Transit method
- Sees whole sky
- 7,525 candidates & 618 confirmed
2021 - Present JWST
- Transit method + spectroscopy for atmosphere
- 1 exoplanet
- Measured chemistry from 1 atmosphere
What doppler exoplanet programs are there?
0.3 m/s accuracy from HARPS & HIRES (echelle grating theory & implementation)
How many confirmed exoplanets are there today?
5,860: 500 earth-like by size & 70 by mass. 16 probably earth-like exoplanets (G or M Type)
How did Kepler Graph Exoplanet Properties?
- PIC
Name some probable earth-like exoplanets.
2015 kepler 452 b
2016 proxima centauri b
TRAPPIST-1 e, f, g
2017 Ross 128 b
TOI 715 b
Gliese 12 b
Describe Kepler 452 b & its problems for life.
Distance: 1,400 ly
Size: 1.5xEarth
Mass: Unknown
Star Type: G2V (sun)
Habitable Zone: yes, star is 1.5 byrd older than sun
Surface T: 17 F
Too far to detect atmosphere
Problems: CMEs 10x those from sun observed & probably tidally locked
Describe Proxima Centauri b & its problems for life.
Distance: 4.2 ly
Size: Earth
Mass: 1.3xEarth
Star Type: M
Habitable Zone: yes
Surface T: -38 F
Method: Doppler
Close enough to detect atmosphere
Problems: more stellar wind, M type stars flare a lot, probably tidally locked (liquid water on one side, ice on other)
2016 breakthrough starshot: - microchip to alpha centauri with laser propulsion & take photos of b
Describe TRAPPIST-1 System
7 earth-like exoplanets with 3 in the habitable zone
Transit timing variations => densities => abundant water
Clear & obvious light curves
Habitable Zone TRAPPIST Planets: 40 lys away & M Type
- E: 0.9xEarth, -17F
- F: 1.0xEarth, -65/2000 F
- G: 1.0xEarth, -103 F
Hubble UV date => possible abundant water
Probably tidally locked
Describe Ross 128 b & its problems for life.
Distance: 11 ly
Size: 1.6xEarth
Star Type: M
Surface T: 80 F
Habitable Zone
Problems: more stellar wind & little flares, probably tidally locked, no transits => hard to detect atmosphere
Describe TOI 715 b
Planet Type: Super Earth
Transit (TESS)
137 ly away
3.02 Earths in mass
1.55xEarth radius
Describe Gliese 12 b
Planet Type: Super Earth
Transit (TESS)
39.7 ly away
3.87 Earths in mass
0.958xEarth radius
