Extrasolar Planet Searches

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Extrasolar Planet Searches

• planets are faint
• Jupiter 10-9 (optical) to 10-4 (far IR) as bright
  as the Sun
• planet and star are close together
• at 10 pc, Jupiter 0.5 arcsec from Sun
• exozodiacal dust is a clouding problem

Like looking for a firefly, next to a lighthouse,
on a foggy night but, Jupiter pulls on the
Sun! 13 m/sec radial velocity half
amplitude 0.52 milliarcsec astrometric half
amplitude at 10 pc
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Sun Rules Our Solar System
Sun Rules Our Solar System
gt 99.5 of the mass gt 99.999 of the
light but planets have MASS Jupiter has
1/1000th mass of Sun planets have
SIZE Jupiter has 1/100th area of Sun
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Types of Objects
object mass radius
fuels
stars mass (minor tweaks for age, composition,
multiplicity) brown dwarfs mass age (changing
temperature, 2000 K ? 500 K) planets mass
composition radiation environment
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Planet Detection Methods
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Planet Search Techniques
Indirect Methods technique what you get 1.
pulsar timing phot flash intervals orbit,
mass 2. radial velocities spec Doppler
velocities most orbital elements, min mass 3.
perturbations astr star wobble orbit, mass 4.
transits phot dips in light curve orbit, mass,
radius Direct Methods 5. imaging phot take
picture orbit, mass
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Indirect Methods Wobble
Wobbles Jupiter around Sun 13 km/sec Sun
wobble 13 m/sec can be measured! Earth
around Sun 30 km/sec Sun wobble 0.1 m/sec
(special cases only)
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1. Pulsar Timing
pulsars spin incredibly regularly pulses of
light are timed using
photometry if pulse timing changes
something pulling on it 1994 first planets
discovered formed after star died?
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2. Radial Velocities
star moves toward/away from us spectroscopy used
to measure Doppler shift 95 of extrasolar
planets discovered this way Jupiters pull
13 m/sec but, you cant get the mass of
the pulling object!
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Radial Velocity Curve
first definitive extrasolar planets discovered
pulsar planets! first sub-brown dwarf mass
object not this one!
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55 Cancri
radial velocities
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periodogram
55 Cancri
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1 Planet Fit
55 Cancri
but, the residuals are high
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Second Period
55 Cancri
15.9 y
2nd period
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2 Planet Fit - Inner Planet
55 Cancri
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2 Planet Fit - Outer Planet
55 Cancri
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2 Planet Fit periodogram
55 Cancri
44.3 d
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Planet 3
55 Cancri
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55 Cancri Planetary System
and now, there are 5 planets (maybe) companion
star at 1000 AU
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..