1. MOA-II microlensing exoplanet survey
0.25
Takahiro Sumi
(Nagoya univ.)
the MOA collaboration

2. planetary microlensing
0.5

3. Sensitivity of various methods
RV　
transit
Direct image
Microlensing：
not rely on flux from host
1.25
small planet：　down to Earth
1-6 AU ： around snow line
Faint star :M-dwarf, brown dwarf
No host ：　free floating planet
Far system:　galactic distribution
Credit Bennett

4. Sensitivity of microlensing1

5. Microlensing observation global network
Survey Group
Follow-up Group
Micro
lensing
Alert 
MOA(NewZealand)
OGLE(Chile),
(no observation in 2009)
Wide field
Low cadence
PLANET
FUN
Pointing each candidate
High cadence
Anomaly
Alert  1

6. MOA (since 1995) （Microlensing Observation in Astrophysics） （ New Zealand/Mt. John Observatory, Latitude： 44S, Alt: m ）
Mirror : 1.8m
CCD : 80M pix.
FOV : 2.2 deg.2
3/4

7. MOA (until ~1500) （the world largest bird in NZ）
height:3.5ｍ
weight:240kg
can not fly
Extinct 500 years ago
（Maori ate them)
0.5

8. Observation by MOA 50 deg.2(20Mstars) 1obs./night.(>MJup)
1obs./95min.(Mjup)
1obs./47min. (Mnep)
1obs./15min. (M)
G.C.
3/4
489events(3planets) (16/9/2009)

9. Real-time Anomaly check at Mt.John
The planet found
on 11/9/2009
3/4
anomaly

10. The first planet via microlensing OGLE 2003-BLG-235/MOA 2003-BLG-53
Mass： ~3MJ, Sep. : ~4AU
1/4

11. 2nd Exoplanet Discovery by lensing
:OGLE 2005-BLG-71
(Udalski, et. al.2006
Dong et al. 2008)
ML=0.46±0.04
DL=3.3±0.4kpc
Mp=3.5±0.3MJ
Sep=3.6±0.2AU
V~103km/s (HST)
Data from OGLE, FUN,
PLANET & MOA
The most massive
Planet at wide sep for M-dwarf
Challenging to form in core-accretion model
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Thick disk

12. 5.5 Earth mass:OGLE-2005-BLG-390
Sep~3AU
Proved
microlensing
is sensitive to
Super earth
0.5
The smallest Planet！(at that time)
(Beaulieu et al. 2006, Nature,439,437)

13. Jupiter/Saturn analog : OGLE-2006-BLG-109L
Host mass
２５multiple system
Habitable zone
snow line
giant planets are supposed to form outside of snow line, but
not observed
First case that both giant planets are outside of snow line
1.25
OGLE-2006-BLG-109L
Jupiter, Saturn

14. The smallest host star：MOA 2007-BLG-192
Bennett et al. 2008
With planet
No planet
Mhost=0.06 ( ) M
Mp =3.3 ( )MEarth
MOA
OGLE
VLT-NACO(AO) image
Lens is faint:
Late M-dwarf or
brown dwarf
Can be
determined
by HST
5 years later 1
No flux
from
Lens

15. Summary of Planet candidates
Gould et al. 2006:
“Cool Neptune” are common in K,M-dwarf： ~40% (>16% at 90% confidence.)”
consistent with formation
theory. (Ida & Lin, 2004) 1
preliminary.
Credit Bennett

16. Galactic distribution
Host mass
Uniform in DL
>60% of lensing events
are due to bulge lens
Sun GC
Distance
Density distribution 1
Few Planets in GB!?
(be careful: there may be
Observational bias)

17. Free floating planet half planets rejected after 108yr Free floating
Planet scattering Simulation by Veras et al. 2009
half planets rejected after 108yr
Free floating
Microlensing can find
tE=1.2days
~1MJ
0.5

18. summary 9 exoplanets (8system) via microlensing published
3 exoplanets in preparation.
MOA is the only survey group in 2009 (489events so far)
3(+2) exoplanets candidates in 2009 so far.
Unique planets:
The largest Giant planet at wide sep. around M-dwarf in Thick disk
Jupiter/Saturn analog
Exoplanet around Brown dwarf
”Cool Neptune“ are common in K,M-dwarf
Evidence of few exoplanets in the bulge??
Free floating planets
Earth Mass planet soon!
075

19. end

20. OGLE-2007-BLG-368 (MOA-2007-BLG-308)
q=1x10^-4, sep= 0.9RE
Keck, AO, K-band
OGLE, I-band

21. Planetary microlensing
D(kpc)
ML(M) Mp
Sep (AU)
OGLE-2003-BLG-235/MOA-2003-BLG-53
θE,Bayesian,flux limit
OGLE-2005-BLG-169
OGLE-2005-BLG-071
θE,Parallax,Astrometry.Thick disk. Most Massive planet in M-dwarf
OGLE-2005-BLG-390
θE,Bayesian
OGLE-2006-BLG-109
θE, Parallax
MOA-2007-BLG-192
θE,Parallax.VLT,Smallest host
MOA-2007-BLG-400
OGLE-2007-BLG-368
In preparation
OGLE-2007-BLG-349
MOA-2007-BLG-197
MOA-2008-BLG-310
If blend is lens