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Life in the Universe
I. astronomy
“If you wish to make an apple pie from scratch, you must first invent the Universe.”
Carl Sagan (1934-1996)
Páll Jakobsson (Palli)
([email protected])
10 January 2013
1. Inngangur
• 1.1 Aaaaa
• 1.2 Bbbbb
Distance: 25 light years
Tracking Fomalhaut b from 2004-2012
Distance: 130 light years
4
M = 9 ∙ MJupiter
Distance: 25 light years
Distance: 70 light years
Known Exoplanets
• 1992: a few are discovered around a neutron star!
• 1995: the first around Sun-like star (indirect measurement).
• January 2013: 854 (http://exoplanet.eu):
1) Radial velocity + astrometry: 498 (386 planetary systems)
2) Transits: 291 (236 planetary systems)
3) Microlensing: 16 (15 planetary systems)
4) Imaging: 32 (28 planetary systems)
1), 2) and 3) are indirect measurements.
Venus Transit in June 2012
Transit Graph
9
Transit Graph
Provides
information on
the radius of the
exoplanet.
10
Probability of a Transit Detection?
11
Where is Kepler Looking?
12
The Kepler Planet Candidates (~2300)
(NB: only 105 confirmed planets)
Kepler-20: An Unusual Planetary System
(5 planets in small orbits)
Kepler-20: large, small, large, small, large
Kepler-20b:
1.9 ∙ REarth
Kepler-20e:
0.9 ∙ REarth
760 °C
Kepler-20c:
3.1 ∙ REarth
Kepler-20f:
1.0 ∙ REarth
430 °C
Kepler-20d:
2.8 ∙ REarth
16
(the first rocky exoplanet to be discovered)
6 planets!
18
The Habitable Zone (shown in green)
19
Earth 2.0
Kepler-47
(a system with more than one planet orbiting a pair of stars)
Astrometry (ísl: stjörnuvagg)
• A system of two (or more) bodies orbit around their mutual centre
of mass.
• The change in the stellar position (wobble) gives the planet mass.
• Example: MJupiter and d = 1 AU. Assume the system lies 3 light years
from Earth. Stellar wobble: 1 milliarcsecond.
• Now put an “Earth” instead and move the system to 30 light years.
Stellar wobble: 0.3 microarcsecond.
• No chance measuring that today.
• SIM PlanetQuest: 2016?
26
Motion of the Sun (distance: 30 ly)