Transcript Paul Butler - James E. Neff

High Cadence
Searches for
Extrasolar
Planets
The discovery of extrasolar planets in the past decade was one
of the most remarkable achievements of the century, and the
culmination of centuries of speculation.
National Academy of Sciences, Decadal Review of Astrophysics
Planet Mass Distribution
Detection Limit:
~ 0.2 MJUP @ 1 AU
Five Neptunes:
Gl 436
55 Cnc d
 m Ara
• HD 190360
• Gliese 581
Butler et al.
McArthur et al.
Santos et al.
Fit Excludes
1st bin.
Planet – Metallicity Correlation
2
Pplanet ~ (NFe/ NH)
Fischer & Valenti 2005
Previous Evidence:
G.Gonzales, N.Santos
Abundance
Analysis of
1000 stars on
planet search .
Metallicity Models:
Ida & Lin
Kacper Kornet
et al.
7000 Å
4000 Å
© NSF/NO
Dr. Gillian Nave, NIST
Key to Doppler Measurements:
Wavelength Calibration
4995 – 6000 Ang.
 Thousands of I2 lines
 3 m/s Precision


Spectrometer PSF:
Conveyed by I2 line
shapes.
The Next Decade:
3 m/s versus 1 m/s
3 m/s Minimal (3-sigma) detection of Jupiter analog
Eccentricity of Jupiter analog is uncertain (+/-0.2)
Non-detection of Saturn-mass at 5 AU
1 m/s Jupiter analog is 10-sigma detection
Uncertainty of eccentricity is +/-0.02
Saturn-mass at 5 AU is a 4-sigma detection
Super-Earths detectable in 4-day orbits
Detection sensitivity similar/better than SIM
Obstacles to 1 m/s
Stellar oscillations
Stellar granulation
Stellar rotation
Photons
Systematic Errors
P-modes in Solar-type stars
Alpha Cen A (G2 V)
Amp ~ 1.5 m/s
Per = 5 min
- Seismology
-Noise:
Avg over
P-modes !
K dwarfs: 1 meter/sec
Alpha Cen B (K0V)
Acoustic p-modes:
Amp < 1 m/s
10 Earth-Masses
P = 50 day
Aliasing
1 day Obs.
Single telescope
Single telescope
5 Earth-Masses
P = 50 day
1 Earth-Mass
P = 4.2 d
Mstar = 0.5 MO
Magellan Planet Finder Spectrograph
Jeff Crane (OCIW)
Steve Shectman (OCIW)
Paul Butler (DTM)
Ian Thompson (OCIW)
f/11 telescope focal surface
f/11 to
f/5
Optical
layout
ThAr & QTH
lamps
slit
CCD
R4 grating
guid
er
beamsplitte
r
22 March 2008
fold mirrors
prism
collimator +
camera
Magellan SAC
fresnel+PMT
17
The APF Planetometer
A high resolution spectrometer optimized
for ultra-precision radial velocity work
Constant gravity environment
• Athermalized optical train
• High efficiency (35%)
l/Dl = 100,000 (for 1 arcsec slit)
• Passively compensated space-frame
• 1 m/s velocity precision
• Cost: $2 million (NASA)
•
APF Predicted Efficiency
The result of littrow echelle, prism CD, and all-dioptric system
0.4
0.35
0.3
Efficiency
0.25
0.2
0.15
0.1
APF System Efficiency
HIRES (2005)
0.05
UVES + KUEYEN (2005)
0
0.3
0.4
0.5
0.6
0.7
Wavelength (microns)
0.8
0.9
1
Exoplanet Target Stars
Spectral Type
F8V and later
Activity
Chromospherically quiescent: R’hk < -4.8
1 m/s: Long View
Keck
AAT
Mag
APF
12+ nights per semester
25+ nights per semester
25+ nights per semester
82+ nights per semester
Every Saturn mass planet out to 9 AU
Every Neptune mass planet out to 1 AU
Super-Earths out to 0.3 AU
Earth-mass planets out to 0.1 AU
Solar System analogs
Habitable planets
People More Important Than Me:
Steve Vogt, UCSC
Steve Shectman, Carnegie Observatories
Jeff Crane, Carnegie Observatories
Chris Tinney, UNSW
Hugh Jones, U of Hertfordshire
Greg Laughlin, UCSC
Dante Minniti, Catolica Santiago
Pamela Arriagada, Catolica Santiago