Life in the UniverseI. astronomy

Páll Jakobsson (Palli)(pja@hi.is)

10 January 2013

“If you wish to make an apple pie from scratch, you must first invent the Universe.”Carl Sagan (1934-1996)

1. Inngangur

• 1.1 Aaaaa• 1.2 Bbbbb

Distance: 25 light years

Tracking Fomalhaut b from 2004-2012

4Distance: 130 light years

Distance: 25 light yearsDistance: 70 light years

M = 9 M∙ Jupiter

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

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Transit Graph

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Transit Graph

Provides information on the

radius of the exoplanet.

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Probability of a Transit Detection?

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Where is Kepler Looking?

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 R∙ Earth

Kepler-20e:0.9 R∙ Earth

Kepler-20c:3.1 R∙ Earth

Kepler-20f:1.0 R∙ Earth

Kepler-20d:2.8 R∙ Earth

760 °C 430 °C

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(the first rocky exoplanet to be discovered)

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6 planets!

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The Habitable Zone (shown in green)

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?

Motion of the Sun (distance: 30 ly)