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What have (pre-Kepler) radial velocity surveys
told us about exo-planetary science?
Ch/Ge128
We have dreamed of
extrasolar planets for a
long time, …
English engraving 1798
(and Physics Today 4/2004).
Now we can detect them!
Jupiter mass planets from <0.05
to >50 astronomical units!
C. Marois (2010)
Kepler is
pushing well
into the hot
Neptune &
super-Earth
regime.
How do we do this?
Discovery space for
indirect methods:
Radial velocity
Astrometry
(r=distance to the star)
Mayor, M. & Queloz, D. 1995, Nature, 378, 355
Udry, S. et al. 2002, A&A, 390, 26
Jovian planets
througout the
0.05-5 AU region.
And…
Updated plots follow.
No strong preference
for orbital distances…
…except for a
“pile up” of hot
Jupiters at P~3 days.
Planetary characteristics? Some trend in M versus R (bias?), but
beyond 0.05-0.1 AU, little preference for low eccentricities:
Eccentricities. II. Short Period Circularization
Even with incompleteness, strong preference for ~Jovian mass:
Stars are different, turnover at low mass!
Orion IMF
“The brown dwarf
desert”?
Does this tell us
that stars and
planets form
differently?
Is there an eccentricity preference w/mass? Not really…
Marcy, G. et al. 2005, astro-ph/0505003
Is there an eccentricity preference w/mass? Not really, part II…
?
Butler, R.P. et al. 2006, ApJ, 646, 505
Another clue as to formation: Planet formation efficiency
correlates strongly with metallicity!
Fischer, D.A. & Valenti, J. 2005, ApJ, 622, 1102
What about planet formation efficiency & stellar mass?
Radial velocity surveys mostly focused on Sun-like stars. Why?
Active
Chromospheres
Low-contrast
Lines
Johnson, J.A et al. 2007, ApJ, 665, 785
What about planet formation efficiency & stellar mass?
Clever idea for higher
mass A stars:
Look at older systems
that have evolved
off the main sequence.
Johnson, J.A et al. 2007, ApJ, 665, 785
What about planet formation efficiency & stellar mass?
M4 – K7
K5 – F8
F5 - A5
Two preliminary findings
(that are being tested with
larger surveys):
1. Planet formation
efficiency increases w/mass.
2. The proportion of hot
Jupiters decreases w/mass
(not observational bias).
Johnson, J.A et al. 2007, ApJ, 665, 785
What about planetary multiplicity? Complex doppler patterns:
Summary of several of the known multiple planetary systems:
Marcy, G. et al. 2005, astro-ph/0505003
A super earth & GJ 876?
Rivera, E.J. et al. 2005,
(see class web site)
GJ 876 orbits
evolve with time
(expected w/mutual
perturbations)!
What about
other systems?
Rivera, E.J. et al. 2005,
(see class web site)
A habitable super-Earth? The GJ 581(M3V) system:
Vogt, S.S. et al. 2010,
(arXiv:1009.5733v1)
HD 168443
b: 7.2 Mj 58 days
c: 17 Mj 1739 days
=1/29.98 ?!
30:1?
HD 12661
b: 2.3 Mj 263 days
c: 1.6 Mj 1444 days
=1/5.5
11:2?
47 U Ma
b: 2.5 Mj 1089 days
c: 0.76 Mj 2594 days
=1/2.4
Gleise 876
b: 1.89 Mj 61 days
c: 0.56 Mj 30 days
HD 37124
b: 0.75 Mj 152 d
c: 1.2 Mj 1495 d
ups And
b: 0.69 Mj 4.6 d
c: 1.9 Mj 241.5 d
d: 3.75 Mj 1284 d
HD 82943
b: 1.63 Mj 444 d
c: 0.88
222 d
55 Cnc
b: .84 Mj 14.6 d
c: 0.21 Mj 44.3 d
d: 4 Mj 5360 d
3:1!
What we know:
- ~1% of solar-type stars have Hot Jupiters
-~7% of solar-type stars have >Mj planets in the
“terrestrial planet” region. Extrapolation of current
incompeteness suggests >12% w/planets @ <20 AU.
- multiple planetary systems are ~common
- planetary resonances are ~common
What can explain these properties?
Theory
Disk-star- and
protoplanet
interactions lead
to migration
while the gas is
present. Coreaccretion?
1 AU at 140 pc
subtends 0.’’007.
Simulation G. Bryden, JPL
Thus, need to study objects in this phase…
Jupiter (5 AU):
V_doppler = 13 m/s
V_orbit = 13 km/s
Core-accretion models can now be compared to observations:
Data
Tests?
Planets
versus
metallicity:
Ida, S. & Lin, D. 2004, ApJ, 616, 567
Observed
in open
circles.
Early disk models held that eccentricities were DAMPED. Not so fast…
Goldreich, P. & Sari, R. 2003, ApJ, 585, 1024
Goldreich
& Sari 2005
Need an
initial
e~0.01.