Extrasolar Planets Lecture 4: Discoveries & Results A/Prof. Quentin A Parker PHYS178 - other worlds: planets and planetary systems1

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 Running for more than 11 years on the AAT  Measures Doppler shifts to very high precision  Use iodine gas to imprint markers on starlight PHYS178 - other worlds: planets and planetary systems4

6 The Anglo-Australian Telescope

 Initially: as many planets as possible!  But to remain competitive, they are looking for:  Solar System analogues  The lowest mass objects we can detect  Are trying to answer two questions:  How common are planetary systems and the pre- conditions for life?  How do stars and planetary systems form?  Are currently monitoring 250 bright Sun-like stars down to about V=7.5 mag PHYS178 - other worlds: planets and planetary systems7

 More than 400 extrasolar planets!  Over 25 systems with more than one planet  S ystems similar to our Solar System now being found PHYS178 - other worlds: planets and planetary systems8 Most planets discovered so far have masses similar to Jupiter and Saturn

PHYS178 - other worlds: planets and planetary systems9 55 Cnc d 55 Cancri currently holds the record for most number of known planets: 5

PHYS178 - other worlds: planets and planetary systems10 55 Cancri holds the record for most number of known planets: 5

PHYS178 - other worlds: planets and planetary systems11 Epsilon Eridani b  Eri also has a disc made up of dust and gas surrounding it

PHYS178 - other worlds: planets and planetary systems12 HD b - “Osiris” First transiting planet found appears to have a “cometary tail”

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PHYS178 - other worlds: planets and planetary systems14 Most planets have eccentric orbits rather than circular like our Solar System

PHYS178 - other worlds: planets and planetary systems15 Most planets have eccentric orbits rather than circular like our Solar System

PHYS178 - other worlds: planets and planetary systems16 Many Jupiter mass planets exist very close to their parent star - closer than Mercury!

PHYS178 - other worlds: planets and planetary systems17 Several transiting planets have much lower density than predicted by theory!

PHYS178 - other worlds: planets and planetary systems19 Recently three planets with 4.2, 6.7 and 9.4 Earth masses were found around a nearby red dwarf star

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PHYS178 - other worlds: planets and planetary systems22 … the stars are getting in the way

Motion on a star’s surface can mimic a planet through Doppler shifts, especially: Magnetic fields and starspots Convection or mixing PHYS178 - other worlds: planets and planetary systems24 We need to understand the stars better!

PHYS178 - other worlds: planets and planetary systems 25 Systems more like our Solar System Larger telescopes and more sophisticated techniques

PHYS178 - other worlds: planets and planetary systems26 Go to Space With NASA & ESA Kepler Terrestrial Planet Finder Image a planet Find another Earth…