extrasolar planets emre işık (mps, lindau) s 3 lecture origin of solar systems 14 february 2006
TRANSCRIPT
Extrasolar planets
Emre Işık (MPS, Lindau)
S3 lecture
Origin of solar systems
14 February 2006
Outline
• Planet detection methods– Methodology– Some recent results
• Statistical properties of exoplanets• Future prospects
Struve, O. 1952 Obs., 870, 199
Detection techniques IPrecise stellar radial velocities to observer
N. S
trob
el
N. S
trob
el
to observer
N. S
trob
el
Detection techniques IITransit photometry
a = (PorbR) / t
f / f = (Rp / R)2
Detection techniques IITransit photometry
Advantages
• Easy (if automated!), small telescopes with good sites/detectors
• Possibility to detect low-mass planets, especially from space (Kepler mission, 2008)
Disadvantages
• Transit probability low; simultaneous observations of many stars
• Confusion with starspots, multiple stars
Planets around binary stars
Deeg (1998)
Reflection effect
HST light curve of HD 209458 b
Brown et al. (2001) • Stellar radius and limb-darkening profile • Planet's mass and radius • No rings around the planet • No moons with M > 3 ME (repeated obs.)
Detection techniques IIIMicrolensing
Detection techniques IIIMicrolensing eventsOGLE 2003-BLG-235/MOA 2003-BLG-53
Discovered planet: 1.5 MJ @ 3 AU
Bond et al. 2004, Astroph. J. Letters , 606 , L155
Detection techniques IIIMicrolensing events
Discovery of a Cool Planet of 5.5 Earth Masses. OGLE-2005-BLG-390
Beaulieu et al., 2006, Nature, 439, 437
Discovered planet: 5.5 ME @ 2.6 AU
Detection techniques IVAstrometry
“Celestial” motion of the Sun due mainly to Jupiter & Saturn, as seen from 33 light years
away…
Astrometry
A Jupiter analog orbiting 5 AU from a solar-type star produces an astrometric amplitude of 0.5 milliarcsec (mas).
A star with planet close to (about 1 arcmin) to a star without planet is needed.
Direct, short CCD exposure at Palomar 5m and Keck telescopes may yield 0.1 mas.
Palomar test-bed interferometer yields 60-70 μas, VLTI should allow 20 μas.
Space missions may do better as interference from terrestrial atmosphere is eliminated.
As of 1998, no object has been found.
Technique is in its infancy. Big telescope resources are needed.
Detection techniques VDirect imaging !
Detection techniques VDirect imaging !
Visible light
Infrared light
• Name: 2M1207 b
• Msini: 5 ± 1 MJ
• Radius:1.5 RJ
• Temperature1240 ± 60 K
• Semi-major axis: (projected dist.) ~ 55 AU
• Orbital period: > 2450 yr
• Mass (star/M_sun): 0.025 NACO/VLT image, Chauvin et al. 2005
Detection techniques VDirect imaging !
Substellar companion to GQ Lupi
• IR image (NACO/VLT) GQ Lupi (A) orbited by a planet (b) at a distance of ~20xJupiter-Sun.
• GQ Lupi: 400 ly, 0.7 M
• Mass: 1-42 MJ
Detection techniques VI [reflection/absorption]
spectroscopy
Detection techniques VI [reflection/absorption]
spectroscopy
Detection techniques VI [reflection/absorption]
spectroscopy
Caution: “planet occurrence” is biased by RV sensitivity!
Properties of the detected planets
Lineweaver & Grether 2003
Properties of the detected planets
Lineweaver & Grether 2003
Extrapolations
Lineweaver & Grether 2003
Lineweaver & Grether 2003
Evolutionary models
• Different assumptions on the inhibition of cooling by irradiation from the parent star, and the planet's internal structure (Burrows et al. [2000], Bodenheimer et al. [2001] and Guillot and Showman [2002])
Fig.: Collier Cameron (2002)
The future:Future of future:
2015 - 2025
CO2
O3