Transcript Extrasolar planets

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 I
Precise stellar radial
velocities
N. Strobel
to observer
Detection techniques II
Transit photometry
Df / f = (Rp / R)2
pa = (PorbR) / Dt
Detection techniques II
Transit photometry
Planets around binary stars
Advantages
• Easy (if automated!), small
telescopes with good sites/detectors
• Possibility to detect low-mass
planets, especially from space
(Kepler mission, 2008)
Reflection effect
Disadvantages
• Transit probability low;
simultaneous observations of many
stars
Deeg (1998)
• Confusion with starspots, multiple
stars
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 III
Microlensing
Detection techniques III
Microlensing events
OGLE 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 III
Microlensing events
Discovery of a Cool Planet of 5.5 Earth Masses. OGLE-2005-BLG-390
Discovered planet:
5.5 ME @ 2.6 AU
Beaulieu et al., 2006, Nature, 439, 437
Detection techniques IV
Astrometry
“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 V
Direct imaging !
Detection techniques V
Direct imaging !
Visible light
Infrared light
Detection techniques V
Direct imaging !
•
•
•
•
•
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
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
Fig.: Collier Cameron (2002)
• 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])
The future:
Future of future:
2015 - 2025
O3
CO2