Transcript KEPLER`s

Planetary Systems Orbiting Diverse Stars
Lecture 1: Introduction & Methods
1. Introduction
2. Techniques for discovery & study
3. The NASA Kepler mission
Where do we stand today?
Planets Known to Orbit Other Stars:
• Total: 330+ ( 31 systems) discovered to-date
• Statistics:
• Gas giant planets, like Jupiter & Saturn,
exist around >12% of stars (Marcy et al.);
• Lower-mass planets (Super-Earths, ~12 known to-date)
are more common (Mayor et al.);
• No Earth-like planets yet …
Small stars, Brown dwarfs, & planets
Burrows 2000)
Evolution of luminosity with time
for different masses
Properties of planets & small stars
Models: Baraffe et al.
four different ages:
0.5, 1, 3, & 5 Gyr
Red: Pont et al. (2005)
OGLE-TR-122
The Planets of our Solar System
New types of
planets:
Hot Jupiters
Super-Earths
(Sasselov 2008)
Super-Earths
“Confusion region”
Mass range:
~1 - 10 Earth mass
The super-Earths M-R diagram
H2O
Fix one ratio:
Earth-like Fe/Si
Valencia, Sasselov, O’Connell (2007)
(Sasselov 2008)
Image: S.Cundiff
Super-Earths:
excellent homes
for life
Techniques for discovery:
Star-to-planet inequalities
• In light: 1010 (optical) to 107 (infrared)
• In mass: 105 to 103
• In size:
102 to 10.
Exoplanet discovery space:
2007 & looking forward
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Planned Kepler space mission:
may detect Earth-like planets,
but measure only size, not mass
Direct Detection of Planets
• Direct detection is challenging because of the
technical
limits of
telescopic
observations
Direct Detection of Planets
• Three planets
orbiting HR8799
…if star’s age
is < 300 Myr
(Marois et al. 2008)
Direct Detection of Planets
• There may
be more
planets,
but more
obs needed
to confirm
even this
one.
(Kalas et al. 2008)
Radial Velocities (Doppler method):
Discovery & Mass measurement
Radial velocities seen
in star HD 209458 the variation is due
to a planet that is less
massive than Jupiter.
(Mazeh et al. 1999;
Marcy et al. 2000)
HD 209458b: a Hot Jupiter
The HARPS planet-search program
- Geneva Observatory
ESO 3.6 – La Silla
-
Physikalisches Institut, Bern
Haute-Provence Observatory
Service d’Aeronomie, Paris
ESO
1 m/s
(from C. Lovis)
HD 40307
HARPS-N Spectrometer on WHT
HARPS-NEF:
Harvard Origins
Initiative
with Obs. Geneve
on the
William Herschel
telescope (WHT),
Canary Islands
A HARPS clone,
but for several
improvements…
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Harvard/Smithsonian/MIT astro-comb project
Summer 07: Ti:sapphire femtosecond laser comb
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2008: develop high-rep rate
comb for astro applications
and demo on mountain-top
Fall 2007: characterize with astro spectrograph
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Li et al. (2008,
Nature, April)
2009: Optimized system for
1 cm/s Doppler shift precision
Transits: A Method for Planet
Discovery & Study
Transit Measurements
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Transit & eclipse of HD189733b
Heather Knutson & Dave Charbonneau (2007)
OGLE-TR-113b
Doppler Shift
Transit Light Curve
Konacki, Torres,
Sasselov, Jha (2004)
The HAT Network: FLWO Mt.Hopkins Arizona
… and Hawaii Mauna Kea
We have discovered >11 new planets with it in 2 years.
(Bakos et al. 2009)
What can we learn from
transiting extrasolar planets
HD 209458b: Dimming of light due
to transit, observed with HST.
Tells us
DIRECTLY:
Planet radius,
INDIRECTLY:
Planet density
Planet composition
Brown, Charbonneau, Gilliland, Noyes, Burrows (2001)
Transits of exoplanets from Hubble:
Illustration of high precision: s(RP)~3%
Light Flux
TrES-1
Spot
HD 209458
Time
Brown et al. (2006)
Mass-Radius
Diagram:
Hot Jupiters
Super-Earths
(Sasselov 2008)
Bakos, Noyes, Pal, Latham, Sasselov et al. (2009)
A New super-Neptune: HAT-P-11b
Transit & eclipse of HD189733b
Heather Knutson & Dave Charbonneau (2007)
Spectrum for HD 189733b
Inverse Residual Flux
Obtained by transit transmission & eclipse emission
Wavelength
(Swain et al. 2008)
New 2 m Spectrum for HD 189733b
NASA Kepler mission: transit search for planets
Cygnus / Lyra
(RA=19h23m, Dec=44.5d)
Completing the Copernican Revolution:
the discovery of “New Earth”
NASA Mission - Mar. 2009
Kepler is ready
to launch:
Mar. 5, 2009
Kepler expected yields:
~ 500 super-Earths,
~ 50 Earth analogs;
(5-10% good radii)
Assembly at Ball Aerospace
The “PROBLEM” with KEPLER:
not able to get data on masses for
small planets
- reflex amplitudes will be
less than 30 cm /sec.
SOLUTION:
build a novel Doppler instrument
to fit on a large telescope.
 Use it to measure masses,
and hence mean densities
for KEPLER’s best candidate Earths & super-Earths!
HARPS-N Spectrometer
Synergy with Kepler:
Provide ability to reach RV
amplitudes of about 10 cm /sec.
Given Porb and phase from transit,
this can translate to 10% masses
in the Super-Earth and Earths
regime.
HARPS-N by Harvard - Geneva
on the William Herschel
telescope (WHT), Canary Isl.
HARPS-N Spectrometer on WHT
HARPS-NEF:
Harvard Origins
Initiative
with Obs. Geneve
on the
William Herschel
telescope (WHT),
Canary Islands
A HARPS clone,
but for several
improvements…
QuickTime™ and a
decompressor
are needed to see this picture.
Some Conclusions:
1. Extrasolar Earths - a worthy (and historic) goal:
• help us understand planet formation in general
• help us constrain pre-biotic chem / pathways to life
2. We now have the tools - to discover & study:
• Transits (Kepler), spectrograph (astro-comb)
Super-Earths
“Confusion region”
Mass range:
~1 - 10 Earth mass
Super-Earths as proxies for Earth
How to distinguish mini-Neptune from super-Earth:
< Three types
of atmospheres
(Miller-Ricci, Seager,
Sasselov 2008)
Super-Earths as proxies for Earth
(Miller-Ricci, Seager,
Sasselov 2008)
How to distinguish mini-Neptune from super-Earth: