2015年年度度岡⼭山ユーザーズミーティング
2015年年8⽉月17⽇日（⽉月）-18⽇日（⽕火）@国⽴立立天⽂文台三鷹  すばる棟  ⼤大セミナー室

⼤大宮正⼠士太陽系外惑星探査プロジェクト室, 国⽴立立天⽂文台  & ABC

晩期  M 型矮星の  Hα 線観測による  IRD 地球型惑星探索索
サンプルの選定
1．イントロ：地球型惑星検出に向けた戦略略
2．地球型惑星探索索のサンプルの選定
3．KOOLS/188cm望遠鏡での観測と現状
  晩期M型矮星  è  Hα線の観測è  地球型惑星探索索

系外惑星サイエンスの次のステップ： 　ハビタブルな地球型惑星の理理解
ドップラー観測期間の限界

惑星質量量（MEarth）

10000

1000

Jupiter
100

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

10

Earth1>30MEarth:10-30MEarth
3-10MEarth
0.1
0.5-3MEarth
0.01
0.5-5MEarth@HZ :

.0M S
1
@
s

un

m/ Radial velocity

0c
K=1

限界
の
度度

精
法の
ー
プラ
ハビタブル
ドッ
ゾーン
M=0.2MSun
0.1

ハビタブル
ゾーン
M=1.0MSun
1
1AU

TransitDirect Imaging
Microlensing
Astrometry

10

100

軌道⻑⾧長半径（AU）

Infrared  Doppler  instrument  (IRD)                                                                      for  the  Subaru  telescope  ¤ IRD：  InfraRed Doppler instrument, 2016年年春ファーストライト予定¤ 望遠鏡： 　 　 　すばる望遠鏡（IRナスミス焦点）¤ 観測波⻑⾧長域： 　0.97-1.75um （Y, J, H–band）¤ 波⻑⾧長分解能： 　70,000¤ 波⻑⾧長校正： 　 　レーザー周波数コム¤ 安定性： 　真空チャンバー、セラミック光学ベンチ等 　➡1m/sの精度度で視線速度度測定を可能にする= 　近⾚赤外ドップラー法で地球型惑星を狙える

NAOJ¤ IRD/Subaru  planet  search¤ ターゲット： 　晩期M型矮星（M4-‐‑‒M9）¤ 可視/近⾚赤外3m級望遠鏡では難しい  ¤ ゴール： 　~∼50惑星＆~∼10地球型惑星＠HZ¤ 1地球質量量の惑星をハビタブルゾーンに検出する¤ 低質量量星周りの地球型-‐‑‒⽊木星型惑星形成の理理解¤ ⽇日本の系外惑星の装置、観測、理理論論の連携

世界で初めて系外地球型惑星の特徴と形成とハビタビリティに迫るallowing its radius to be measured. Combined with the real massestimate, the radius leads to the average density of the planet. In thepresent case, given a stellar radius36 of 0.863 times the solar radius andassuming the radius of the planet is that of the Earth, the planet transit
probability is estimated at 10%, with a transit depth of 1024. The
detection of a planet transit, only possible from space, would allow
us to confirm the expected rocky nature of the detected planet arounda Centauri B.
The r.m.s. radial velocity induced by the stellar rotational activity
amounts to 1.5 m s21 on average. The detection of the tiny planetary
signal, with a semi-amplitude K 5 0.51 m s21, thus demonstrates thatstellar activity is not necessarily a definitive limitation to the detectionof small-mass planets. Using an optimized observational strategy andthe present knowledge about activity-induced radial-velocity effects,
it is possible to model precisely and mitigate activity signals, andtherefore improve considerably the planet detection limits.
With a separation from its parent star of only 0.04 AU, the planet isorbiting very close to a Centauri B compared to the location of thehabitable zone. However, the observed radial-velocity semi-amplitude is equivalent to that induced by a planet of minimum mass fourtimes that of Earth in the habitable zone of the star (P 5 200 d; ref. 37).

1.

Mayor, M. & Queloz, D. A Jupiter-mass companion to a solar-type star. Nature 378,
355–359 (1995).
2. Schneider, J., Dedieu, C., Le Sidaner, P., Savalle, R. & Zolotukhin, I. Defining andcataloging exoplanets: the exoplanet.eu database. Astron. Astrophys. 532, A79(2011).
3. Fuhrmann, K. et al. BESO échelle spectroscopy of solar-type stars at Cerro
Armazones. Mon. Not. R. Astron. Soc. 411, 2311–2318 (2011).
4. Valenti, J. A. & Fischer, D. A. Spectroscopic properties of cool stars (SPOCS). I. 1040
F, G, and K dwarfs from Keck, Lick, and AAT planet search programs. Astrophys. J.
Suppl. Ser. 159, 141–166 (2005).
5. Santos, N. C. et al. Spectroscopic metallicities for planet-host stars: extending thesamples. Astron. Astrophys. 437, 1127–1133 (2005).
6. Neuforge-Verheecke, C. & Magain, P. Spectroscopic analysis of the Alpha Centaurisystem. Astron. Astrophys. 328, 261–268 (1997).
7. Pourbaix, D. et al. Constraining the difference in convective blueshift between thecomponents of a Centauri with precise radial velocities. Astron. Astrophys. 386,
280–285 (2002).
8. Xie, J.-W., Zhou, J.-L. & Ge, J. Planetesimal accretion in binary systems: could
planets form around a Centauri B? Astrophys. J. 708, 1566–1578 (2010).
9. Thébault, P., Marzari, F. & Scholl, H. Planet formation in the habitable zone of a
Centauri B. Mon. Not. R. Astron. Soc. 393, L21–L25 (2009).
10. Lissauer, J. J., Ragozzine, D., Fabrycky, D. C., Steffen, J. H. & Ford, E. B. Architectureand dynamics of Kepler’s candidate multiple transiting planet systems. Astrophys.
J. Suppl. Ser. 197, 8 (2011).
11. Latham, D. W., Rowe, J. F., Quinn, S. N., Batalha, N. M. & Borucki, W. J. A firstcomparison of Kepler planet candidates in single and multiple systems. Astrophys.
J. 732, L24 (2011).
12. Mayor, M. et al. The HARPS search for southern extra-solar planets. XXXIV.
Occurrence, mass distribution and orbital properties of super-Earths and
Neptune-mass planets. Astron. Astrophys. (submitted); preprint at http://arxiv.org/
abs/1109.2497 (2011).
13. Lovis, C. et al. The HARPS search for southern extra-solar planets. XXVIII. Up toseven planets orbiting HD 10180: probing the architecture of low-mass planetarysystems. Astron. Astrophys. 528, A112 (2011).
14. Pepe, F. et al. The HARPS search for Earth-like planets in the habitable zone. Very
low mass planets around HD29794, HD85512 and HD192310. Astron. Astrophys.
534, A58 (2011).
15. Dumusque, X., Santos, N. C., Udry, S., Lovis, C. & Bonfils, X. Planetary detection
limits taking into account stellar noise. II. Effect of stellar spot groups on radialvelocities. Astron. Astrophys. 527, A82 (2011).
16. Kjeldsen, H. et al. Solar-like oscillations in Alpha Centauri B. Astrophys. J. 635,
1281–1290 (2005).
17. Carrier, F. & Bourban, G. Solar-like oscillations in the K1 dwarf star alpha Cen B.
Astron. Astrophys. 406, L23–L26 (2003).
18. Del Moro, D. Solar granulation properties derived from three different time series.
Astron. Astrophys. 428, 1007–1015 (2004).
19. Title, A. M. et al. Statistical properties of solar granulation derived from the SOUP
instrument on Spacelab 2. Astrophys. J. 336, 475–494 (1989).
20. Dumusque, X., Udry, S., Lovis, C., Santos, N. C. & Monteiro, M. J. Planetary detection
limits taking into account stellar noise. I. Observational strategies to reduce stellar
oscillation and granulation effects. Astron. Astrophys. 525, A140 (2011).
21. Boisse, I. et al. Disentangling between stellar activity and planetary signals. Astron.
Astrophys. 528, A4 (2011).
22. Howard, R. & Murdin, P. in Encyclopedia of Astronomy and Astrophysics (ed. Murdin,
P.) 3173–3177 (Institute of Physics Publishing, 2000).
23. DeWarf, L. E., Datin, K. M. & Guinan, E. F. X-Ray, FUV, and UV observations of a
Centauri B: determination of long-term magnetic activity cycle and rotation
period. Astrophys. J. 722, 343–357 (2010).
24. Meunier, N., Desort, M. & Lagrange, A.-M. Using the Sun to estimate Earth-likeplanets detection capabilities. II. Impact of plages. Astron. Astrophys. 512, A39(2010).
25. Gray, D. F. The Observation and Analysis of Stellar Photospheres (Cambridge Univ.
Press, 1992).
26. Brandt, P. N. & Solanki, S. K. Solar line asymmetries and the magnetic filling factor.
Astron. Astrophys. 231, 221–234 (1990).

1.5
1.0

–1

RV (m s–1)

視線速度度RV(m/s)
RV (m s )

0.5

2
0.5
–2
0.0
–6
54500
–0.5

­−0.5
6
2
–2
–6

54550

54600

b–1.0
–1.5
–2.0

Dumusque et al. 2012
0.0

0.2

54900

0.4

0.6

54950

0.8

位相
55000
1.0

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

0.6

a

0.5

b Long-term
activity

p
b

0.4

(
s
0.2
r
ARTI
p
0.1
p
0.30
b
c
d Rotational
10.00
periodprobability (FAP) 0.25
lower thana conservative 1% limctwoperiods
arealiasesofone
another.
A
carefulanL
0.20 Harmonics
5.00
ture in frequency of the periodogram suggests thatn
0.15
54650
is the true signal (Supplementary Information secf
0.00
0.10
The global model
makes use of parameters assocf
–5.00
0.05
timescales. One could thus worry whether the signo0.00
ihave been introduced during
the processof elim
100
101
102
103
54600 55000 55400 55800
signals. We performed Monte Period
Carlo(d)simulations mt
55050
JD – 2400000 (d)ユリウス⽇日（⽇日）周期 (days)
could be the case, and concluded
that the signalt
Figure 1 | Radial velocities
ofaCentauriBandfittingthelong-timescaleartefact of the fitting process (Supplementary Infor
stellar signals. a, Raw radial velocities (RV) and the fit of the binary’s signature t¤The⾃自転、磁場周期による変化
peak at 3.236 d in the radial-velocity resi(a Centauri B orbiting a Centauri A). In the residuals (c), signals at long periodwith a FAP of 0.02%. Using a Markov chain Monv
0.3

Normalized power

α Centauri B, 0.934MSunの視線速度度変化（N6 a
観測=459）2.0–1¤ 1.16地球質量量惑星の報告¤ Dumusque et al. 2012¤ 振幅K~0.5m/s、周期3⽇日¤ 星固有の変化に埋もれる

RV – binary (m s–1)

¤ アルファケンタウリB

視線速度度RV(m/s)
RV (km s )低質量量星惑星検出の難題：星の活動
RESEARCH ARTICLE

連星による変化

磁場活動に伴う変化

主星の⾃自転周期に伴う変化
6 c
Phase

Figure 5 | Phase-folded radial-velocity curve with a period of 3.2357 d.
Green dots, radial velocities after correction of the stellar, binary andeffects. Red dots, the same radial velocities binned in phase, with a
2 coordinates
bin size of 0.05. The error bar of a given bin is estimated using the weighted–2 r.m.s. of the global fit residuals (including the planetary fit) that make this bin,by the square root of the number of measurements included in this bin.
–6 divided
This estimation of the bin error bars assumes Gaussian noise, which is justified
55260
55280
55320 in time.55340
by the binning in phase,
which regroups55300
points that are uncorrelated
The r.m.s. around the planetary solution is 1.20 m s21 for the raw points (green
6 dots) and 0.21 m s21 for the binned points (red dots). The red curve represents
the global fit solution of the planet, with a semi-amplitude of 0.51 m s21.

55360
55380signals, highlighted
arevisible. Theseby grey arrows (‘long-term activity’) in¤ 惑星偽検出の可能性がある
coupleda genetic
algorithm
characterize
periodogram b, correspondto theto
effectof the magnetic
cycle.toThegrey curve inthed¤Hatzes
2013
c
shows
the
variationofthelow-frequency
part
of
the
activity
index
scaled to thepera
we obtained a signal with a well-constrained
2
K
radial-velocity variation.
Whenthese low-frequency
perturbations
are but is com
2
The
eccentricity
ispoorlyconstrained–2 2 1 0 | N A T U R E | V O L 4 9 1 | 8 N O V E M B E R 2 0 1 Macmillan
Publishers Limited. All rights reserved©2012è 活動度度が⼩小さい星を選び
removed, signals induced by rotational
activity, pointed out by grey arrows in n
–6
withina1.4s
uncertainty (Supplementary Infor
55600
55650
55700
55750
periodogramd, can be seen at the rotation period of the star and its harmonics. T
ジッターの影響を除去する
To in
fitc,è
thisJD – 2400000 (d)JD, Julian date. Error bars
1s. planetary signal simultaneously with tF
時間（JD）

地球質量量惑星の検出に向けた戦略略¤ 戦略略1: 観測ターゲットの選定¤ 徹底的に、表⾯面活動度度が低く、⾃自転速度度が遅いlateM型矮星を選ぶ¤ 戦略略2: ⾼高頻度度多回数観測¤ 表⾯面活動、装置変化に伴う変化を⼩小さくするために短期間に多数回の視線速度度モニター観測を⾏行行う¤ 戦略略3: 視線速度度＆表⾯面活動同時観測¤ ターゲット毎の表⾯面活動調査を視線速度度モニター観測と同時に進める戦略略1: 観測ターゲットの選定
u基本パラメータがわかっている天体
u年年周視差、実視等級、etc.
u⻑⾧長期間の超精密視線速度度モニターに適する天体
u⼗十分な視線速度度精度度を達成可能
è 射影⾃自転速度度vsiniが遅い晩期M型矮星
è ⾃自転周期、Vsini、Hα線、スペクトル型
u表⾯面活動による視線速度度ジッターが⼩小さいè 活動度度が低い天体
è XUV、Hα線、⾃自転周期u⽬目指すサイエンスからの要請
u低質量量星、単独星 　etc.

M型矮星で期待される精度度と活動度度†フォトンリミット

視線速度度精度度（m/s）

6
5

M3

4

M6

3
2
0

V

Y

Band

J

10
10

3m/s
11
1

1

10

1m/s

10

100

Vsini（km/s）

Reiners et al. 2010によると、
M4-M6 Vsini>10km/s: 20%
M7-M9 Vsini>10km/s: 50%

M91

視線速度度精度度（m/s）

星スペクトルのみ†から期待される精度度の⾒見見積もり M3(¢), M6(¢), M9(¢)
SN~300@Y-band, Vsini=0km/s, R=80,000
Ref. Reiners+2010

⾃自転速度度と期待される精度度
100
SN~100, M5, Y-band, Reiners+2010

H

West et al. 2011によると、活動度度が⾼高い星（M4-M6）：10-50%
活動度度が⾼高い星（M7-M9）：60-80%

KOOLS/OAO1.88m望遠鏡での観測¤ Hα輝線周囲の中分散分光観測¤ Hα輝線の有無と強度度を確認¤ スペクトル型、⾦金金属量量など¤ 活動度度が低くて⾃自転速度度が遅い
晩期M型矮星を探す¤ Hα線のEWHAが⼩小さくXUVの放射が弱い星であれば、⾃自転
速度度が遅い星が⼤大半を占める¤ ジッターが⼩小さくて、表⾯面活動が安定している星を選ぶ¤ M4~M9の近傍晩期M型矮星の性質を明らかにする¤ 太陽近傍（25pc以内）の晩期
M型矮星の統計¤ スペクトル型、⾦金金属量量、活動性、表⾯面重⼒力力の決定

Hα線の等価幅¤ 観測⽅方針

⾃自転速度度 (km/s)

Hα線の強度度(EWHA)と⾃自転速度度の関係
    inactive  (EWHA>-‐‑‒0.75  &  No  strong  XUV)な 　M型矮星の内、9割はvsini<4km  s-‐‑‒1である○  :  低質量量星のプロット(0.08~∼0.3MSunu)×  :  Hα  での活動度度(EWHA,  West+11)が⾼高い星
×  :  XUV  (ROSAT,  GALEX)での活動度度が⾼高い星
×  :  HaとXUVで活動度度が⾼高いと分かっている星
Hα,  UV,  X  線指標：Lepine+13,  AJ,  145,  102⾃自転速度度V  (sini)：  e.g.  Jenkins+09,  ApJ,  704,  975破線:  5  km  s-‐‑‒1, 　⼀一点破線  :  EWHA=-‐‑‒0.75

先⾏行行研究HγHβA&A 577, A128 (2015)

HeI, NaI, NaI

Hα Li

KI

NaI

Alonso-Floriano+2015¤

West+2011：
SDSSで受かったM型矮星70,841個のカタログ（天体が暗すぎる）
Fig. 1. Six representative
CAFOS spectra. From top to bottom, spectra of standard stars with spectral type 1.0 and 0.5 subtypes earlier than the¤Lepine+2013：固有運動カタログの中で明るい星1408個の分光カタログ（J＜９の明るい星のみ）
V583 Aur B), and standard stars with spectral type 0.5 and 1.0 subtypes later than the target (black). We mark activity-, gravity-, and youth-

¤

3
2
1
Alonso-Floriano+2015：CARMENESカタログのM型矮星753個の観測（>M5のM型矮星が⼤大多数）
absorption bands at the bottom. Note the three first lines of the Balmer series in emission in the spectrum of the target star.

target (black), standard star with the same spectral type as the target (cyan), the target star (red; in this case, J04393+335 – M4.0 V, Simbad name:sensitive lines and doublets at the top of the figure (H , H , He i D , Na i D and D , H↵, Li i, K i, and Na i, from left to right) and molecular観測ターゲットとなる晩期M型矮星¤ ターゲット候補：  約200星 　（既知の情報から選定）¤ J~7-11.5 mag¤ Mass~0.1-0.3MSun¤ Sp. type：M4-M8¤ 既知の下記天体を除く¤ 実視連星¤ 活動度度が⾼高い天体¤ XUV輝線星¤ Hα輝線星¤ フレア星¤ 回転変光星¤ vsini>4km/sの星¤ 追加条件¤ 太陽からの距離離（<25pc）¤ 主星質量量によりバイアス

本観測などにより約100星に絞る
0.2-0.3MSunの星：約?0星
0.1-0.2MSunの星：約?0星fication
proved< 0.82h values
stands426 (=
ubdwarf
where¤ita star7), and
Jahreiss
ar, with
resence8). Our¤f Hα inarf. It is
f in theeaker inspectralof theirather tondheadse samemean¤
ofWe thusne halfy (Gizis

tallicity
opticalpoor Mfor the subset of stars observed at UH. We first examine any possible correlation between the optical to infrared r − KS color(taken as a proxy for V − I) and the ζ index. Figure 17 plotsr − Ks as a function of spectral subtype, with the dots colorcoded for the ζ values of their associated M dwarf (top left
panel). We find a tight relationship between r − Ks and spectral
subtype, which we fit using a running median. The residuals
装置： 　KOOLS/188cm望遠鏡
are plotted in the top right panel, and show no evidence of awith ζ . There683
are a significant number of outliers¤ correlation
グリズム： 　VPHwith redder r − Ks colors than the bulk of the M dwarfs: these¤ likely
スリット幅= 1.0” ~errors
R=2,000
indicate systematicin estimating the synthetic r
magnitudes.
The absences ofclear correlation suggests¤ band露露出時間~ 200-1200
~ any
SN>30
that an optical-to-infrared color such as r − KS is not sensitive enough to detect small metallicity variations, at least at the
観測： 　88星/22夜の割り当て
metal-rich end.
The synthetic g − r and r − z colors are plotted in Figure 17¤ (lower-left
2014年年： 　実施率率率= 36%（望遠鏡稼働率率率）
panel). The redder stars (r − z > 1.2) show a wide
scatterin g − r, on the order of what is predicted for stars with¤ 8⽉月（4夜）、9⽉月（6夜）、10⽉月（3夜）
a range of metallicities −0.5 < [Fe/H] < 0.5. Though we do¤ not2015年年： 　実施率率率= 45%（望遠鏡稼働率率率）
find a clear trend between
the synthetic g − r colors andtheζvaluesmeasured
in
the
same
stars, the high-ζ stars (red¤ 3⽉月（4夜）、5⽉月（5夜）
and orange dots on the plot) do seem to have lower values of¤ g先⾏行行研究による観測がある星：5星− r on average than the low-ζ ones (green dots). The trend issuggestive of a metallicity link to both the g − r colors and theζ values, and should be investigated further with data of higher
解析： 　Hα線の等価幅の測定
precision.

観測＆解析¤ ⼀一次元化：IRAF
7. CHROMOSPHERIC ACTIVITY¤ Hα線と擬似コンティニュームとの⽐比較
evaluate the presenceof Hαemission in our M dwarfs,¤To Equivalent
width
of in
Hα（EAHA）
we used the Hα equivalent width index EWHA defined as¤ EWHA <⎡-0.75Å であれば活動的⎤# 6571.61
14 Å 6557.61 S(λ)dλ$#%⎦ ,EWHA = 100 Å ⎣1 −# 66256550
100 Å 6500 S(λ)dλ + 6575 S(λ)dλM4V型星のKOOLSスペクトル

Equivalent  width  of  Hα（EAHA）

結果 〜～EWHAと恒星質量量の関係〜～
-5
-4
-3
-2
-1

ActiveInactive

0
1
2
0.05

0.1

0.15

0.2

0.25

星質量量（太陽質量量）

0.3

0.35

サンプル中の活動的なM型矮星¤ ターゲット候補：  約200星 　（既知の情報から選定）¤ X線： 　ROSAT All-Sky Bright Source Catalogue (Voges+ 1999)¤ UV： 　GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)¤ これまでのHα観測：   　計115星¤ 先⾏行行研究による観測： 　30星程度度¤ CARMENES input catalogue of M dwarfs (Alonso-Floriano+2015)¤ A Spectroscopic Catalog of the Brightest (J<9) M Dwarfs in the
Northern Sky (Lepine+2013)¤ 本研究によるKOOLS観測： 　85星
¤ ただし、RAが18~24hに固まっている。。

¤ 活動度度が⾼高い星（EWHA > -0.75）： 　計13星
¤ Mass > 0.15 Msunの星：

3星（68星）è 　4.4%¤ Mass < 0.15 MSunの星：

10星（17星）è 　59%

まとめと今後¤ IRD/Subaruによる地球型惑星探索索¤ 厳選した晩期M型矮星を対象としたハビタブル地球型惑星探索索¤ ⽬目標とするサイエンス¤ 近傍M型矮星周りのハビタブル地球型惑星の発⾒見見 　（✔惑星質量量決定）¤ 晩期M型矮星における地球型惑星の統計理理解 　 　 　（✔発⾒見見数の増⼤大）¤ 地球型惑星検出が可能な、表⾯面活動の弱い晩期M型矮星の選定¤ 本研究：KOOLS/OAO1.88m望遠鏡での中分散分光観測（R〜～2,000, SN~50)¤ 活動度度が低くて⾃自転速度度が遅い晩期M型矮星を探す¤ HαのEWHAが>-0.75であれば、活動度度が低く⾃自転速度度が遅い天体¤ 観測：  22晩/1年年（平均稼働率率率：40%） 　è 85星の観測¤ 結果：  活動度度が⾼高い星を13星同定した¤ Mass > 0.15 Msunの星：  4.4%;    Mass > 0.15 Msunの星：  59%

¤ 今後：  観測を継続したい¤ できるだけ明るくて、質量量が低い星（特にM<0.15MSun）を観測したい¤ RAの分布の偏りがないようにする