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Protoplanetary systems
and extrasolar planets
Betelgeuse
Distance: 197 pc
Orion Nebula
Distance: 412 pc
Orion Constellation
Rigel
Distance: 260 pc
Region of star formation: Orion nebula
Distance: 412 pc
Apparent magnitude: m = +4.0
Age: 300,000 years old
65″
60″
Protoplanetary disks in Orion nebula
Protoplanetary disks in Orion nebula
Size of Solar System
The young star Beta Pictoris
Distance: d = 19.44 ± 0.05 pc
Mass: M = 1.75 M⊙
HST images
The young star Beta Pictoris
Distance: d = 19.44 ± 0.05 pc
Mass: M = 1.75 M⊙
Very Large Telescope image
The Solar System
Mercury
Telluric planets
Earth
Venus
Mars
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The Solar System
Uranus
Jupiter
Giant gaseous planets
Neptune
Saturn
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Solar system
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Solar system
The Trans Neptunian Objects (TNO):
Pluto, Quaoar, Eris, and Sedna (diameters 1200-2400 km, dwarf planets)
Sedna
Eris
Pluto
Quaoar
Neptune
To this scale, the Oort Cloud starts about 10 meters
from the center of the orbit of Neptune. The Earth’s orbit
extends much less than a millimeter from the center.
Giordano Bruno (Nola 1548 – Roma 1600)
«..l’infinito, universo e mondi innumerabili.»
«…un Sole Nero inghiottirà nello spazio il sole, la luna, e tutti pianeti che ruotano intorno al sole"
"Ad un corpo di dimensione infinita non può essere attribuito né un centro né un confine”
"L'uomo viaggerà nel cosmo e dal cosmo apprenderà il giorno della sua fine”
(De l'Infinito Universo et Mondi)
“…. le stelle sono infinite e sono soli lontanissimi attorno ai quali girano pianeti e alcuni di questi mondi sono abitati da esseri
intelligenti.”
Extrasolar planets (as of September 2014)
1.000
904
900
800
Number of planets
700
600
500
400
300
185
200
119
100
0
7
1998
11
20
2000
13
30
2002
25
30
2004
33
29
2006
62
66
2008
Year of discovery
123 132
81
2010
2012
2014
Kepler space observatory (NASA)
Launched in 2009 to discover extrasolar planets
51 Pegasi: the first extrasolar planet (1995)
Radial velocity of 51 Pegasi
Sizes of planets (February 2014)
800
Number of planets
600
400
200
0
Jupiter size
Neptune size
Super-Earth size
Earth size
Planets in the dwarf star Gliese 581
Distance: 20.2 ± 0.2 l.y. (6.25 ± 0.05 pc)
Planets in dwarf star Gliese 581
?
Kepler-186f: first Earth-size planet In 'Habitable Zone'
Main-sequence M1 dwarf star Kepler-186
Distance: 151 ± 18 pc
Habitable Zone
How extrasolar planets are found
• Direct imaging
• Radial velocity
• Transiting
• Gravitational lensing
• Transit-timing variation
Extrasolar planet M1207b
Distance: 52 pc
3-20 times the mass of Jupiter
Distance from the star: 7.8 distance Jupiter−Sun
Direct imaging
Two main difficulties:
1. A small angular separation
2. A huge contrast in luminosity
The Sun
Jupiter
Sun–Jupiter at 4 light years = 4 arcsec
Sun–Jupiter at 100 light years = 0.15 arcsec
Sun–Earth at 100 light years = 0.03 arcsec
Sun–Earth at 330 light years = 0.01 arcsec
Star up to 109 times brighter
than planet
Star up to 109 times brighter
than planet
One solution: coronograph to block light
Main-sequence star HR 8799
Distance: 129 l.y. (39 pc)
Mass: M = 1.5 M⊙
Radial velocity
Gravitational perturbation induced by Jupiter on Sun
Jupiter orbit
Period: 11.9 years
Distance: 5.2 AU
Velocity: 13 km/s
Mass: m = 1.9×1027 kg
Period: 11.9 years
Distance: 0.005 AU
Velocity: 12 m/s
Mass: M = 2.0×1030 kg
Mass center
M / m = dm / dM = vm / vM
Sun orbit
d: distance from mass center
v: velocity around mass center
Dynamical
effects:
• Astrometry
• Radial velocity
Doppler shift
Highest resolution today:
λ/∆λ = 100,000 ⟾ v = 3 km/s
(not enough for Jupiter-Sun system)
Jupiter−Sun ⟾ Amplitude = 12.5 m/s Period = 11.9 years
Earth−Sun ⟾ Amplitude = 0.1 m/s Period = 1 year
Sensitive to short periods and more massive planets !
Occultation or transit
Evaporation of Hot-Jupiters
Eclipse 4/01/2011 & ISS
Credit: Thierry Legault
Transit photometry
Transit probability
Edge-on orbit
(i = 90o)
Face-on orbit
(i = 0o)
The first transiting planet: Osiris
French mission COROT
COROT-7
Period: 0.85 days
Mass: < 9 ME
Radius:1.58 RE
NASA mission Kepler
Kepler-10b
Period: 0.84 days
Mass: 4.5 ME
Radius:1.42 RE
Kepler light curve for HAT-P-7b
Gravitational lensing
Albert Einstein
T
Gravitation (micro)-lensing 32 candidates (September 2014)
M = 2.6 (+0.8/−0.6) MJ
Semi-major axis: 4.3 (+2.5−0.8) AU
Video: http://www3.nd.edu/~bennett/moa53-ogle235/
Transit-timing variation
Gravitational perturbation induced by planets
Used for the discovery of Neptune (1846)
confirmed Newton’s Laws of gravitation
Ne
n
u
t
p
e
U
u
ran
s
Mathematician Urbain Le Verrier
Transit-timing variation
Video: http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=60
Summary (September 2014)
1822 Planets
1137 Planetary systems
467 Multiple planet systems
51 Direct imaging
574 Radial velocity
1147 Transiting
32 Gravitational microlensing
a few Transit-timing variation
Extrapolation: several hundreds million of Jovian extrasolar planets in
the Milky Way with periods of 5 or fewer days
Discovered extrasolar planets per year and by detection method
(as of September 2014)
direct imaging microlensing transit timing radial velocity
Present: atmosphere
Future: bio signatures
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