3rd DTA Symposium
The Origins of Planetary Systems:
from the Current View to New Horizons
June 1 - June 4, 2015, NAOJ, TokyoBun‘ei Sato
Tokyo Institute of Technology

Masashi Omiya

Extrasolar Planet Detection Project, NAOJ, ABC

InfraredDoppler planet search
for Earth-mass planets
1．Introduction： Toward Earth–mass planet
2．To detect Earth-mass planets using IRD search
3．Simulation of the planet search
low-mass stars è IR Doppler è Earth-mass planets

Recent result: Mass – Semi-major axis
Period limit of Doppler search

Planetary Mass（MEarth）

10000 　Next big step in the research of exoplanets 　  = To understand habitable Earth-like planets

1000

Jupiter
100

K=1m/s @ 1.0MSun
K=0.5m/s

10Earth1n lioisi
Prec>30MEarth:
10-30MEarth
3-10MEarth
0.1
0.5-3MEarth
0.01
0.5-5MEarth@HZ :hodte
ler mppDo
fot
miHabitable Zone
M=1.0MSun

1AU0.1

1.0M S
1@sunm/ Radial velocity

0c
K=1Transit
Direct Imaging
Microlensing
Astrometry

10100

Semi-major axis（AU）

Recent result: Mass – Semi-major axis
Planetary Mass（MEarth）

10000

1000

Jupiter
100

K=1m/s @ 1.0MSun
K=1m/s @ 0.2MSun

10unm/ Radial velocity

0c
K=1Earth1>30MEarth:
10-30MEarth
3-10MEarth
0.1
0.5-3MEarth
0.01
0.5-5MEarth@HZ :.0M S
1@sHabitable Zone
M=0.2MSun

0.1

Habitable Zone
M=1.0MSun

1AU1Transit
Direct Imaging
Microlensing
Astrometry

10100

Semi-major axis（AU）

Planets in the habitable zone
0.1-10 Earth Masses or 0.5-2.0 Earth Radii in conservative Habitable zone¤ Survey of late-type stars(Red frames)

Detected candidates are ONLY
Super-Earth mass planets &Earth-radus planets.

¤

Early M-K type dwarf stars¤Mplanet > 3.8MEarth¤ Survey by Kepller satellite(Blue frames)¤

Difficult to follow-up obs.
¤¤

Too far and too faintNo detection by Doppler

1．We don’t know any possible real “habitable planet” around nearby stars
2．Planetary mass is very important to discuss habitable planets
3．Too small number of detected planets in habitable zone

IRD/Subaru  planet  search  ¤ IRD：  InfraRed Doppler instrument¤ Telescope： 　 　 　Subaru 8.2 m¤ Wavelength：0.97-1.75um （Y, J, H–band）¤ Resolution：¤ Calibration：

70,000 (high resolution)
Laser frequency comb
NAOJ

➡ Infrared RV measurements with 1m/s precision= We can search for Earths around M dwarfs¤ Search  for  Earths  around  late-‐‑‒M  dwarfs  ¤ 1．Very stable spectrograph and calibration¤ 2．Optimized observation strategy¤ 3. Collaboration of theory, observation, andinstrument groups in Japan➡ Understanding characteristics, formation, and habitability of Earths

Why M dwarfs?

0.3
1.0Steller mass (MSun)¤Larger amplitude of RV variation¤ We can detect Earth-mass planets¤Habitable zone is at closer-in orbits (<0.3AU)M6V star GJ406 (Pavlenko et al. 2006)

Flux

Amplitude of RV (m/s)

0.1

Distance from habitable zone (AU)

Amplitude of RV variation 　 　 　 　 　 　Late-type stars:  　 　 　 　 　 　 　＆  ＆Habitable zone（HZ）
Flux peak at infrared

1

2 　Wavelength (micron)¤

Faint in optical, bright in Infrared¤ Very effective in infrared¤A lot of number of samples in solar
neighborhood

Search for Earth-mass planets aroundlate-M type dwarf stars using IRD/Subaru
Difficult to detect Earth-mass planet around solar-type stars

Late-M type dwarfs（M4V-M9V、0.1-0.3 MSun）    Larger Amplitudeè Easier to detect Earth–mass

Shorter periodè Easier to detect Earth–mass
Flux peak in Infrared region

A large number of sample stars in solar neighborhood¤ Search for planets using IRD/Subaru¤ Subaru telescopeè 　A large number of low-mass stars¤ 1m/s precision è 　Easier to detect Earth-mass planets
Main  scienctiﬁc  goals  of  IRD/Subaru  planet  search  1. Discovery of Earth-mass planets in habitable zone
2. Statistical understanding of Earth-mass planets around low mass stars

New instrument:

IRD

Infrared high dispersion spectrographoptimized for very high-accuracy RV measurements

IRD & Subaru telescope_ 　Light fromLaser Comb

Mode scrambler
Resolution : R=70000
Range: 0.97-1.75um
Cryo: 60K (detector), 200K (optical)

Stellar lightfrom AO

Fiber injection
system (AO bench)
Fiber(Comb)

Fiber(star)

Spectrograph

Laser frequencycomb

Spectrometer system（Coude room）

IRD/Subaru
planet searchSearch for Earth-mass planets aroundlate-M type dwarf stars using IRD/Subaru

Toward detection of Earths¤ Strategy 1: Careful target selection¤ To reduce the stellar noise in RV variation¤ To achieve high RV measurement precision¤ Strategy 2: High cadence and high frequency observation¤ To reduce effects of stellar noise and make observing period shorter¤ Strategy 3: Simultaneous RV & activity observation¤ To verify the stellar activity simultaneously 　è Make it possible to detect Earth-mass planets

Strategy 1: Careful target selection¤ J~7-11.5 mag¤ Mass~0.1-0.3MSun¤ V-J>5.5 or <20 pc¤ Without active indicator¤ Properties of targets¤ bright¤ low-mass¤ inactive¤ slow rotation velocity

Screening observations~300 candidates⬇  by Hα line,Vsinii, Binarity, etc.
Select best ~100 stars

Number of stars Number of stars¤ Target candidates：300 stars 　（From catalog）

Effective Temperature（K）

Stellar mass（Solar mass, MSun）

Strategy 2:High cadence observation
１yr.

-5 RV+orbit

RV(m/s)

３yr.

５yr.

O-CTime（days）

Planetary  mass  (Earth  masses)
Planetarymass (MEarth)

5

Simulation of detectability
Simulation of obs.

Orbital  period,  P  (days)
Orbitalperiod (days)

Strategy 3: Activity
diagnostics
RESEARCH ARTICLE–1–1

In the case of α Cen B Dumusque+120.6

a0.5

b Long-term
activity

pb0.4(Fst0.2ARTIra¤ Surface（spot, plage etc.）
p0.1
p0.30
probability (FAP) lowerd thana conservative 1% lim
6 abRotational
c10.00period20.25
ctwo periods are aliases of one another. A careful an–2
Lture in frequency 0.20
of theHarmonics
periodogram suggests that
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is the true signal (SupplementaryInformation sec
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The global model
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Figure 1 | Radial velocities of a Centauri B and fitting the long-timescale
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Caused by Companions

Caused by stellar activity

are visible. These signals,
highlighted
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The grey curve in per
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simultaneouslywith Tt
periodogram d, can be seen atrotation
period signalof the starand its harmonics.

Rotational variation

55650
55700
JD – 2400000 (d)JD（days）

Normalized power

RV – binary (m s–1)

RV(m/s)RV (m s )¤ binary signal¤ Magnetic activity

RV (km s )RV(m/s)¤ RV variation caused by stars

–22.3
–22.4
–22.5
–22.6
–22.7
–22.8
–22.9
–23.0

Our observation plan¤ Target： 　〜～  100 late-M dwarfs¤ More than 50 or 80 RV observations of each star over 1~5 years
2014/11/13

Telescope schedule¤ Start of the survey： 　2016 B or later¤ Other groups will also start in similar season
Display

Oct2014

Current

Sep 2014

Nov 2014¤ Now： 　Assemble and test @ Mitaka/NAOJ¤ 2015 winter： 　First light
Example in a month¤ 2016 first ： 　start test RV observation
S1?B
IRD

¤ Our requested number of nights¤ Number of nights： 　170 nights¤ Subaru Strategic Observation Programs¤ Period： 　5 years¤ Our request schedule of the nights¤ 0.5nights × 7times/month × 9~10runs/year

S1?B
IRD

S1?B
IRD

S1?B
IRD

S1?B
IRD
S1?B
IRD

S1?B
IRD

0.5nights × 7times

Expected number of planets

Expected number of planets
30nights

65

100

135

170

Blue：3-10MEarth
Green：10-30MEarth
Red：>30MEarth

0.5-3MEarth⬇

0.5-5MEarth in HZ⬇

Observation period（yr）

Number of discoveries
Jupiter-mass : 4
Neptune-mass : 7
Super-Earth: 13
Earth-mass: 28
Plan & Condition
Total：170nights
Sample：100
N of obs.：50or80
error : ~1m/s
σ : ~1m/s
Schedule : half night
Model：standard
overhead：8min.

Scientific goals of IRD/Subaru
1. Discovery of Earth-mass planets in habitable zone

Expected numberof planets¤ Minimum Success 　¤ Discovery of a Earth-mass planet in habitable zone

× >1

¤ Full Success 　¤ Understanding of properties of habitable Earthmass planets

× >10

2. Understanding of planets around low-mass stars¤ Minimum Success 　¤ Super-Earth ~ Jupiter mass planets¤ Full Success¤ Earth-mass, Super-Earth ~ Jupiter mass planets
Next science from IRD/Subaru planet search
1. 　Characterization of detected planets
2. 　Targets for direct spectroscopy and search for biomarkers

× >25
× >50

Summary¤ Search for Second Earths around low-mass stars¤ InfraRed Doppler instrument (IRD)¤ Making a new instrument for very precise Doppler (RV)
measurements¤ Our targets : 100 late-M dwarf stars¤ Specific strategy for detecting Earth-mass planets¤ IRD/Subaru planet search （170nights in 5 years 2016~）¤ The occurrence rate of habitable Earth-like planets¤ The statistical properties and formation of Earth-mass planets¤ Uniform statistical understandings :¤ All-size planets: Earth ~ Super-Earth ~ Neptune ~ JupiterThank you for your attention.